Clinical Focus

  • Oncologic Imaging
  • Hepatobiliary and pancreatic imaging
  • Urogenital imaging
  • Gynecologic Imaging
  • Thyroid ultrasound
  • Ultrasound
  • Diagnostic Radiology

Academic Appointments

Administrative Appointments

  • Director of Ultrasound, Radiology (2018 - Present)
  • Body Imaging Fellowship Director, Body Imaging Fellowship (2007 - Present)

Honors & Awards

  • Phi Beta Kappa, Dartmouth College (-)
  • Presidential Scholar, Dartmouth College (-)
  • Summa cum Laude, Dartmouth College (-)
  • Tau Beta Pi, Dartmouth College (-)
  • Utah State Finalist Clinical Vignette Competition, American College of Physicians (2000)
  • 2002 Executive Council Research Paper Award, American Roentgen Ray Society (2002)
  • Outstanding Scientific Paper Award, University of Michigan Health System (2002)
  • 2003 Laurence A. Mack Research Award, Society of Radiologists in Ultrasound (2003)
  • Teacher of the Year Award, Stanford University Department of Radiology (2005-2006)
  • Teacher of the Year Award, Stanford University Department of Radiology (2006-2007)
  • Certificate of Merit - Research Exhibit, American Roentgen Ray Society (2009)
  • Certificate of Merit - Research Exhibit, American Roentgen Ray Society (2010)
  • New Investigator Finalist, American Institute of Ultrasound in Medicine (2010)
  • 2011 Research Award, The Society of Uroradiology (2011-2012)
  • Developmental Cancer Research Award, Stanford Cancer Center (2011-2013)
  • Wylie J. Dodds Research Award, The Society of Gastrointestinal Radiologists (2011-2013)
  • Department of Radiology Angel Funding Grant, Stanford Department of Radiology (2012)
  • Fellow, Society of Abdominal Radiology (2013-)
  • Fellow, Society of Radiologists in Ultrasound (2013-)
  • Cum Laude Award - Educational Exhibit, Radiologic Society of North America (2014)
  • Certificate of Merit - Educational Exhibit, Radiologic Society of North America (2014, 2015)
  • Bronze Award - Educational Exhibit, American Roentgen Ray Society (2016)
  • Poster Merit Award, Society of Abdominal Radiology (2016)
  • Certificate of Merit, American Roentgen Ray Society (2018)

Boards, Advisory Committees, Professional Organizations

  • Fund Oversight Committee, Society of Abdominal Radiology (2019 - Present)
  • Secretary, Executive Board, Society of Radiologists in Ultrasound (2019 - Present)
  • Steering Committee Member, ACR LI-RADS (2016 - Present)
  • Chair, ACR Ultrasound LI-RADS (Liver Imaging Reporting and Data System) Working Group (2014 - Present)

Professional Education

  • Internship:LDS Hospital Intermountain Healthcare (2000) UT
  • Medical Education:University of Utah School of Medicine Registrar (1999) UT
  • Board Certification: Diagnostic Radiology, American Board of Radiology (2004)
  • Fellowship, Stanford University, Body Imaging (2005)
  • Residency:University of Michigan Health System (2004) MI
  • A.B., Dartmouth College, Engineering Sciences (1995)

Community and International Work

  • Asian Health Services, Oakland



    Ongoing Project


    Opportunities for Student Involvement


Research & Scholarship

Current Research and Scholarly Interests

Hepatic imaging
Hepatocellular carcinoma
Novel ultrasound technologies
Perfusion CT imaging of abdominal tumors

Clinical Trials

  • BR55 in Characterization of Ovarian Lesions Recruiting

    This is an exploratory phase II, single center, open label, prospective study of BR55 CEUS for characterization of ovarian lesions in subjects with suspected ovarian cancer.

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  • Contrast-Enhanced Ultrasound Imaging in Diagnosing Liver Cancer in Patients With Cirrhosis Recruiting

    This clinical trial studies how well contrast-enhanced ultrasound imaging works in diagnosing liver cancer in patients with cirrhosis. Diagnostic procedures, such as contrast-enhanced ultrasound imaging, may help find and diagnose liver cancer.

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  • Feasibility 3D Perfusion Ultrasound for Liver Cancer SABR Planning and Response Evaluation Recruiting

    The purpose of this study is to prospectively analyze the value of 3D ultrasound perfusion imaging for treatment planning, the prediction of therapy success, and to monitor the treatment response in patients with a primary or metastatic liver tumor undergoing radiation treatment.

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  • Transabdominal Ultrasound With BR55 for Characterization of Pancreatic Lesions Recruiting

    This is an exploratory, single center, open label, parallel-dose, and prospective study of BR55 CEUS for characterization of solid pancreatic lesions in subjects with suspected PDAC using transabdominal US.

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  • A Phase 2b Study of Modified Vaccinia Virus to Treat Patients Advanced Liver Cancer Who Failed Sorafenib Not Recruiting

    This study is to determine whether JX-594 (Pexa-Vec) plus best supportive care is more effective in improving survival than best supportive care in patients with advanced Hepatocellular Carcinoma (HCC) who have failed sorafenib.

    Stanford is currently not accepting patients for this trial. For more information, please contact Fizaa Ahmed, (650) 725 - 6409.

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  • B-mode Ultrasound Imaging in Detecting Early Liver Cancer Not Recruiting

    This pilot trial studies how well B-mode ultrasound imaging works in detecting liver cancer that is early in its growth and may not have spread to other parts of the body. Diagnostic procedures, such as B-mode ultrasound imaging, may help find and diagnose liver cancer and find out how far the disease has spread.

    Stanford is currently not accepting patients for this trial. For more information, please contact Sunitha Bachawal, 650-724-1472.

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  • Combination SBRT With TACE for Unresectable Hepatocellular Carcinoma Not Recruiting

    To determine the efficacy and toxicity of TACE combined with SBRT

    Stanford is currently not accepting patients for this trial. For more information, please contact Laurie Ann Columbo, 650-736-0792.

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  • Perfusion CT Monitoring to Predict Treatment Efficacy in Renal Cell Carcinoma Not Recruiting

    This pilot clinical trial studies perfusion computed tomography (CT) in predicting response to treatment in patients with advanced kidney cancer. Comparing results of diagnostic procedures done before, during, and after targeted therapy may help doctors predict a patient's response to treatment and help plan the best treatment.

    Stanford is currently not accepting patients for this trial. For more information, please contact Yoriko Imae, 650-498-5186.

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  • Phase I Pilot Study to Evaluate the Prognostic Value of Perfusion CT for Primary Cervical Cancer Not Recruiting

    The investigators hope to learn whether perfusion CT is a useful way to assess primary cervical tumor microenvironment and whether there is a relationship between pretreatment perfusion CT measurements and primary cervical tumor size, lymph node involvement (as assessed by standard of care pretreatment fludeoxyglucose Positron emission tomography/CT (FDG-PET/CT)), and treatment response (as assessed by standard of care 3-month post-therapy FDG-PET/CT).

    Stanford is currently not accepting patients for this trial. For more information, please contact Melissa Usoz, 650-723-8843.

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  • Pilot 3D Contrast-Enhanced Ultrasound Imaging to Predict Treatment Response in Liver Metastases Not Recruiting

    Patients are invited to participate in a research study of liver perfusion (how blood flows to the liver over time). Researchers hope to learn whether perfusion characteristics of liver metastases may be predictive of response to treatment and whether liver perfusion characteristics can be used to follow response to treatment. Patients were selected as a possible participant in this study because they are identified as having liver metastases

    Stanford is currently not accepting patients for this trial. For more information, please contact Risa Jiron, 650-736-1598.

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  • Ultrasound Elastography in Diagnosing Patients With Kidney or Liver Solid Focal Lesions Not Recruiting

    This clinical trial studies ultrasound elastography in diagnosing patients with kidney or liver solid focal lesions. New diagnostic procedures, such as ultrasound elastography, may be a less invasive way to check for kidney or liver solid focal lesions.

    Stanford is currently not accepting patients for this trial. For more information, please contact Juergen Willmann, 650-725-1812.

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  • Ultrasound Elastography in Imaging Patients With Thyroid Nodules Not Recruiting

    This clinical trial studies how well ultrasound elastography works in imaging patients with thyroid nodules. Diagnostic imaging, such as elastography, uses shear waves to measure the stiffness and compressibility of tissue and may be a better way to image thyroid nodules.

    Stanford is currently not accepting patients for this trial. For more information, please contact Harris Naemi, 650-736-6524.

    View full details


2019-20 Courses

Stanford Advisees


All Publications

  • 2017 Version of LI-RADS for CT and MR Imaging: An Update. Radiographics : a review publication of the Radiological Society of North America, Inc Elsayes, K. M., Hooker, J. C., Agrons, M. M., Kielar, A. Z., Tang, A., Fowler, K. J., Chernyak, V., Bashir, M. R., Kono, Y., Do, R. K., Mitchell, D. G., Kamaya, A., Hecht, E. M., Sirlin, C. B. ; 37 (7): 1994?2017


    The Liver Imaging Reporting and Data System (LI-RADS) is a reporting system created for the standardized interpretation of liver imaging findings in patients who are at risk for hepatocellular carcinoma (HCC). This system was developed with the cooperative and ongoing efforts of an American College of Radiology-supported committee of diagnostic radiologists with expertise in liver imaging and valuable input from hepatobiliary surgeons, hepatologists, hepatopathologists, and interventional radiologists. In this article, the 2017 version of LI-RADS for computed tomography and magnetic resonance imaging is reviewed. Specific topics include the appropriate population for application of LI-RADS; technical recommendations for image optimization, including definitions of dynamic enhancement phases; diagnostic and treatment response categories; definitions of major and ancillary imaging features; criteria for distinguishing definite HCC from a malignancy that might be non-HCC; management options following LI-RADS categorization; and reporting. (©)RSNA, 2017.

    View details for PubMedID 29131761

  • Ultrasound Assessment of Acute Kidney Injury ULTRASOUND QUARTERLY Kelahan, L. C., Desser, T. S., Troxell, M. L., Kamaya, A. 2019; 35 (2): 173?80
  • Early Changes in CT Perfusion Parameters: Primary Renal Carcinoma Versus Metastases After Treatment with Targeted Therapy CANCERS Fan, A. C., Sundaram, V., Kino, A., Schmiedeskamp, H., Metzner, T. J., Kamaya, A. 2019; 11 (5)
  • Ultrasound Evaluation in Patients at Risk for Hepatocellular Carcinoma RADIOLOGIC CLINICS OF NORTH AMERICA Fetzer, D. T., Rodgers, S. K., Seow, J. H., Dawkins, A. A., Joshi, G., Gabriel, H., Kamaya, A. 2019; 57 (3): 563-+
  • Role of US LI-RADS in the LI-RADS Algorithm. Radiographics : a review publication of the Radiological Society of North America, Inc Rodgers, S. K., Fetzer, D. T., Gabriel, H., Seow, J. H., Choi, H. H., Maturen, K. E., Wasnik, A. P., Morgan, T. A., Dahiya, N., O'Boyle, M. K., Kono, Y., Sirlin, C. B., Kamaya, A. 2019; 39 (3): 690?708


    The US Liver Imaging Reporting and Data System (LI-RADS) was released in 2017 and is the newest of the four American College of Radiology (ACR) LI-RADS algorithms. US LI-RADS provides standardized terminology, technical recommendations, and a reporting framework for US examinations performed for screening or surveillance in patients at risk for developing hepatocellular carcinoma (HCC). The appropriate patient population for screening and surveillance includes individuals who are at risk for developing HCC but do not have known or suspected cancer. This includes patients with cirrhosis from any cause and subsets of patients with chronic hepatitis B virus infection in the absence of cirrhosis. In an HCC screening or surveillance study, US LI-RADS recommends assigning two scores that apply to the entire study: the US category, which determines follow-up, and a visualization score, which communicates the expected level of sensitivity of the examination but does not affect management. Three US categories are possible: US-1 negative, a study with no evidence of HCC; US-2 subthreshold, a study in which an observation less than 10 mm is depicted that is not definitely benign; and US-3 positive, a study in which an observation greater than or equal to 10 mm or a new thrombus in vein is identified, for which diagnostic contrast material-enhanced imaging is recommended. Three visualization scores are possible: A (no or minimal limitations), B (moderate limitations), and C (severe limitations). ©RSNA, 2019.

    View details for PubMedID 31059393

  • Association of advanced hepatic fibrosis and sonographic visualization score: a dual-center study using ACR US LI-RADS ABDOMINAL RADIOLOGY Choi, H. H., Perez, M. G., Millet, J. D., Liang, T., Wasnik, A. P., Maturen, K. E., Kamaya, A. 2019; 44 (4): 1415?22
  • An update for LI-RADS: Version 2018. Why so soon after version 2017? Journal of magnetic resonance imaging : JMRI Kielar, A. Z., Chernyak, V., Bashir, M. R., Do, R. K., Fowler, K. J., Santillan, C., Sirlin, C. B., Mitchell, D. G., Cerny, M., Tang, A., Elsayes, K. M., Kamaya, A., Kono, Y., Arora, S. S. 2019

    View details for PubMedID 30864185

  • ACR Appropriateness Criteria® Jaundice. Journal of the American College of Radiology : JACR Hindman, N. M., Arif-Tiwari, H., Kamel, I. R., Al-Refaie, W. B., Bartel, T. B., Cash, B. D., Chernyak, V., Goldstein, A., Grajo, J. R., Horowitz, J. M., Kamaya, A., McNamara, M. M., Porter, K. K., Srivastava, P. K., Zaheer, A., Carucci, L. R. 2019; 16 (5S): S126?S140


    Jaundice is the end result of myriad causes, which makes the role of imaging in this setting particularly challenging. In the United States, the most common causes of all types of jaundice fall into four categories including hepatitis, alcoholic liver disease, blockage of the common bile duct by a gallstone or tumor, and toxic reaction to a drug or medicinal herb. Clinically, differentiating between the various potential etiologies of jaundice requires a detailed history, targeted physical examination, and pertinent laboratory studies, the results of which allow the physician to categorize the type of jaundice into mechanical or nonmechanical causes. Imaging modalities used to evaluate the jaundiced patient (all etiologies) include abdominal ultrasound (US), CT, MR cholangiopancreatography, endoscopic retrograde cholangiopancreatography and endoscopic US. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

    View details for PubMedID 31054739

  • LI-RADS: a conceptual and historical review from its beginning to its recent integration into AASLD clinical practice guidance. Journal of hepatocellular carcinoma Elsayes, K. M., Kielar, A. Z., Chernyak, V., Morshid, A., Furlan, A., Masch, W. R., Marks, R. M., Kamaya, A., Do, R. K., Kono, Y., Fowler, K. J., Tang, A., Bashir, M. R., Hecht, E. M., Jambhekar, K., Lyshchik, A., Rodgers, S. K., Heiken, J. P., Kohli, M., Fetzer, D. T., Wilson, S. R., Kassam, Z., Mendiratta-Lala, M., Singal, A. G., Lim, C. S., Cruite, I., Lee, J., Ash, R., Mitchell, D. G., McInnes, M. D., Sirlin, C. B. 2019; 6: 49?69


    The Liver Imaging Reporting and Data System (LI-RADS) is a comprehensive system for standardizing the terminology, technique, interpretation, reporting, and data collection of liver observations in individuals at high risk for hepatocellular carcinoma (HCC). LI-RADS is supported and endorsed by the American College of Radiology (ACR). Upon its initial release in 2011, LI-RADS applied only to liver observations identified at CT or MRI. It has since been refined and expanded over multiple updates to now also address ultrasound-based surveillance, contrast-enhanced ultrasound for HCC diagnosis, and CT/MRI for assessing treatment response after locoregional therapy. The LI-RADS 2018 version was integrated into the HCC diagnosis, staging, and management practice guidance of the American Association for the Study of Liver Diseases (AASLD). This article reviews the major LI-RADS updates since its 2011 inception and provides an overview of the currently published LI-RADS algorithms.

    View details for PubMedID 30788336

  • ACR Ultrasound Liver Reporting and Data System: Multicenter Assessment of Clinical Performance at 1 Year. Journal of the American College of Radiology : JACR Millet, J. D., Kamaya, A., Choi, H. H., Dahiya, N., Murphy, P. M., Naveed, M. Z., O'Boyle, M., Parra, L. A., Perez, M., Pirmoazen, A., Rodgers, S. K., Wasnik, A. P., Maturen, K. E. 2019


    The aim of this study was to evaluate the clinical performance of the ACR's Ultrasound Liver Reporting and Data System (US LI-RADS?) for detecting hepatocellular carcinoma (HCC) in patients at high risk for HCC.In this retrospective, multicenter study, 2,050 patients at high risk for HCC (1,078 men and 972 women; mean age, 57.7 years) at five sites in the United States had undergone screening liver ultrasound from January 2017 to February 2018, and US LI-RADS observation categories and visualization scores were assigned on a clinical basis. Ultrasound reports and patient records were retrospectively reviewed and follow-up imaging studies and/or pathologic reports recorded. Descriptive statistics were generated, and multivariate logistic regression analysis was used to analyze the relationship of clinical and reader-based predictors of limited visualization. Diagnostic performance data were calculated in the subset of patients with confirmatory testing.The most common indications for HCC screening were cirrhosis (n = 1,054 [51.4%]), noncirrhotic hepatitis B virus (n = 555 [27.1%]), and noncirrhotic hepatitis C virus (n = 234 [11.4%]). US LI-RADS observation categories assigned were US-1 (negative) in 90.4% (n = 1,854), US-2 (subthreshold) in 4.6% (n = 95), and US-3 (positive) in 4.9% (n = 101). Visualization scores were A (no or minimal limitations) in 76.8% (n = 1,575), B (moderate limitations) in 18.9% (n = 388), and C (severe limitations) in 4.2% (n = 87). Confirmatory tests including multiphase contrast-enhanced CT or MRI (n = 331) or histopathology (n = 18) were available for 349 patients (17.0%). The sensitivity of US LI-RADS in this subset of patients was 82.4%, specificity was 74.2%, positive predictive value was 35.3%, and negative predictive value was 96.1%.Approximately 90% of US LI-RADS screening examinations were negative, 5% subthreshold, and 5% positive. Visualization scores were diagnostically acceptable in the vast majority (>95%) of examinations. US LI-RADS emphasized sensitivity and negative predictive value, key characteristics of a screening test.

    View details for DOI 10.1016/j.jacr.2019.05.020

    View details for PubMedID 31173745

  • White paper of the Society of Abdominal Radiology hepatocellular carcinoma diagnosis disease-focused panel on LI-RADS v2018 for CT and MRI ABDOMINAL RADIOLOGY Elsayes, K. M., Kielar, A. Z., Elmohr, M. M., Chernyak, V., Masch, W. R., Furlan, A., Marks, R. M., Cruite, I., Fowler, K. J., Tang, A., Bashir, M. R., Hecht, E. M., Kamaya, A., Jambhekar, K., Kamath, A., Arora, S., Bijan, B., Ash, R., Kassam, Z., Chaudhry, H., McGahan, J. P., Yacoub, J. H., McInnes, M., Fung, A. W., Shanbhogue, K., Lee, J., Deshmukh, S., Horvat, N., Mitchell, D. G., Do, R. G., Surabhi, V. R., Szklaruk, J., Sirlin, C. B. 2018; 43 (10): 2625?42


    The Liver Imaging and Reporting Data System (LI-RADS) is a comprehensive system for standardizing the terminology, technique, interpretation, reporting, and data collection of liver imaging with the overarching goal of improving communication, clinical care, education, and research relating to patients at risk for or diagnosed with hepatocellular carcinoma (HCC). In 2018, the American Association for the Study of Liver Diseases (AASLD) integrated LI-RADS into its clinical practice guidance for the imaging-based diagnosis of HCC. The harmonization between the AASLD and LI-RADS diagnostic imaging criteria required minor modifications to the recently released LI-RADS v2017 guidelines, necessitating a LI-RADS v2018 update. This article provides an overview of the key changes included in LI-RADS v2018 as well as a look at the LI-RADS v2018 diagnostic algorithm and criteria, technical recommendations, and management suggestions. Substantive changes in LI-RADS v2018 are the removal of the requirement for visibility on antecedent surveillance ultrasound for LI-RADS 5 (LR-5) categorization of 10-19 mm observations with nonrim arterial phase hyper-enhancement and nonperipheral "washout", and adoption of the Organ Procurement and Transplantation Network definition of threshold growth (? 50% size increase of a mass in ? 6 months). Nomenclatural changes in LI-RADS v2018 are the removal of -us and -g as LR-5 qualifiers.

    View details for PubMedID 30155697

  • Liver Imaging Reporting and Data System (LI-RADS) Version 2018: Imaging of Hepatocellular Carcinoma in At-Risk Patients. Radiology Chernyak, V., Fowler, K. J., Kamaya, A., Kielar, A. Z., Elsayes, K. M., Bashir, M. R., Kono, Y., Do, R. K., Mitchell, D. G., Singal, A. G., Tang, A., Sirlin, C. B. 2018: 181494


    The Liver Imaging Reporting and Data System (LI-RADS) is composed of four individual algorithms intended to standardize the lexicon, as well as reporting and care, in patients with or at risk for hepatocellular carcinoma in the context of surveillance with US; diagnosis with CT, MRI, or contrast material-enhanced US; and assessment of treatment response with CT or MRI. This report provides a broad overview of LI-RADS, including its historic development, relationship to other imaging guidelines, composition, aims, and future directions. In addition, readers will understand the motivation for and key components of the 2018 update.

    View details for PubMedID 30251931

  • Performance of Hepatic Artery Velocity in Evaluation of Causes of Markedly Elevated Liver Tests. Ultrasound in medicine & biology Tse, J. R., Jeffrey, R. B., Kamaya, A. 2018


    The purpose of this study was to assess the utility of peak systolic proper hepatic artery velocity (HAV) in differentiating causes of severely elevated liver function tests. HAV, hepatic artery resistive index and portal vein velocity of 41 patients with severely elevated liver function tests were evaluated. In 19 patients (46%), the causes were structural (e.g., cholecystitis, cholangitis), whereas in 22 patients (54%) the causes were non-structural (e.g., rhabdomyolysis, drug-induced liver injury). The average HAV for structural causes was 138 ± 68 cm/s, and for non-structural causes, 65 ± 29 cm/s (p < 0.0001). An HAV >100 cm/s was correlated with structural causes (p?=?0.0001). With respect to diagnostic performance, this threshold was 79% sensitive and 86% specific, with a high positive likelihood ratio (5.8) and low negative likelihood ratio (0.24). The resistive index and portal vein velocity were not statistically different. In patients with severely elevated liver function tests, an HAV >100 cm/s can help distinguish structural from non-structural causes, which may guide management while awaiting definitive laboratory tests.

    View details for PubMedID 30143340

  • Diagnostic Performance of Margin Features in Thyroid Nodules in Prediction of Malignancy. AJR. American journal of roentgenology Siebert, S. M., Gomez, A. J., Liang, T., Tahvildari, A. M., Desser, T. S., Jeffrey, R. B., Kamaya, A. 2018: 1?6


    The purpose of this study was to evaluate thyroid nodule margins for specific morphologic features and determine the diagnostic performance of these features in differentiating papillary carcinoma from benign thyroid nodules.Nodules measuring 1-3 cm in largest diameter that had been evaluated with high-resolution ultrasound (12-18 MHz) and ultrasound-guided biopsy with definitive pathologic diagnosis were analyzed. Three blinded board-certified readers evaluated high-resolution images of each nodule for jagged edges, lobulated borders, and curved borders along their margins. Reader interpretations were correlated with the pathologic diagnosis to determine the diagnostic performance of each feature. A board-certified pathologist analyzed 10 randomly selected nodules with jagged edges by slide review to evaluate for structural correlation with the imaging finding.The diagnostic performance of jagged edges in papillary carcinoma of the thyroid was 67.4% sensitive and 78.3% specific (odds ratio, 7.44; p < 0.001) for malignancy. Jagged edges correlated with infiltrative variant expansion at slide review. Lobulated borders had sensitivity of 76.1% and specificity of 60.9% for papillary carcinoma (odds ratio, 4.95; p = 0.001) for malignancy. Curved borders were not a significant predictor of papillary carcinoma.Jagged edges and lobulated borders of thyroid nodule margins are statistically significant predictors of papillary carcinoma of the thyroid. Jagged edges correlate with infiltrative-type expansion and may be useful predictors of more aggressive papillary carcinomas.

    View details for PubMedID 29446670

  • Liver Imaging Techniques: Recognition of Uveal Melanoma Metastases. Ocular oncology and pathology Bellerive, C., Ouellet, E., Kamaya, A., Singh, A. D. 2018; 4 (4): 254?60


    The liver is the most common site for metastases of several primary malignancies including uveal melanoma.Review of imaging characteristics of incidental common benign liver lesions including hepatic cyst, hemangioma, focal nodular hyperplasia, and hepatic adenoma and contrasting them with uveal melanoma metastases.Benign hepatic lesions may be cystic or, if solid, relatively stable in size over time. For hepatic lesions larger than 10 mm in size, characteristic imaging features typically allow for confident diagnosis. When lesions are small (less than 10 mm), definitive characterization can be difficult. Moreover, lesions smaller than 10 mm can be difficult to biopsy under ultrasound or computed tomography (CT) guidance, and short-term follow-up will often be useful to assess for stability or progression. Overall, magnetic resonance imaging is more specific than CT scan and at least as sensitive as CT for detecting uveal melanoma liver metastases.New multiple enhancing solid liver lesions should raise suspicion of uveal melanoma liver metastases. Discussion of challenging cases with the radiologist may be beneficial, as pertinent information such as size, location, and molecular prognostication status of the primary tumor can guide radiological interpretation of hepatic lesions.

    View details for PubMedID 30643771

  • LI-RADS 2017: An update. Journal of magnetic resonance imaging : JMRI Kielar, A. Z., Chernyak, V., Bashir, M. R., Do, R. K., Fowler, K. J., Mitchell, D. G., Cerny, M., Elsayes, K. M., Santillan, C., Kamaya, A., Kono, Y., Sirlin, C. B., Tang, A. 2018


    The computed tomography / magnetic resonance imaging (CT/MRI) Liver Imaging Reporting & Data System (LI-RADS) is a standardized system for diagnostic imaging terminology, technique, interpretation, and reporting in patients with or at risk for developing hepatocellular carcinoma (HCC). Using diagnostic algorithms and tables, the system assigns to liver observations category codes reflecting the relative probability of HCC or other malignancies. This review article provides an overview of the 2017 version of CT/MRI LI-RADS with a focus on MRI. The main LI-RADS categories and their application will be described. Changes and updates introduced in this version of LI-RADS will be highlighted, including modifications to the diagnostic algorithm and to the optional application of ancillary features. Comparisons to other major diagnostic systems for HCC will be made, emphasizing key similarities, differences, strengths, and limitations. In addition, this review presents the new Treatment Response algorithm, while introducing the concepts of MRI nonviability and viability. Finally, planned future directions for LI-RADS will be outlined.5 Technical Efficacy: Stage 5 J. Magn. Reson. Imaging 2018.

    View details for PubMedID 29626376

  • Diagnostic Ultrasound for Sonographers Kamaya, A., Wong-You-Cheong, J., Woodward, P., Kennedy, A., Sohaey, R., et al Elsevier. 2018
  • Central echogenic areas in thyroid nodules: Diagnostic performance in prediction of papillary cancer. European journal of radiology Siebert, S. M., Jeffrey, R. B., Gomez, A. J., Kamaya, A. 2018; 101: 45?49


    To determine the diagnostic performance of the "central echogenic area" sonographic finding in differentiating papillary carcinomas from benign nodules and to how this finding may be used to improve fine needle aspiration(FNA) technique/utilization.We retrospectively analyzed ultrasound guided FNAs of thyroid nodules between 1 and 3?cm for central echogenic areas. 92 patients (evenly distributed benign vs papillary carcinoma) were evaluated by a blinded reader for areas of non-shadowing homogenously echogenic centers within the nodules and correlated with FNA proven pathologic diagnosis. A selection of nodules with the central echogenic area finding were selected for further slide review to establish a pathologic basis for the finding.Diagnostic performance of the "central echogenic area" feature in papillary thyroid cancers was 52.2% sensitive and 91.3% specific for papillary thyroid carcinoma with a PPV of 85.7% and NPV of 65.6%. There was a significant correlation with a p?

    View details for DOI 10.1016/j.ejrad.2018.01.029

    View details for PubMedID 29571800

  • Reduced dose CT with model-based iterative reconstruction compared to standard dose CT of the chest, abdomen, and pelvis in oncology patients: intra-individual comparison study on image quality and lesion conspicuity. Abdominal radiology Morimoto, L. N., Kamaya, A., Boulay-Coletta, I., Fleischmann, D., Molvin, L., Tian, L., Fisher, G., Wang, J., Willmann, J. K. 2017


    To compare image quality and lesion conspicuity of reduced dose (RD) CT with model-based iterative reconstruction (MBIR) compared to standard dose (SD) CT in patients undergoing oncological follow-up imaging.Forty-four cancer patients who had a staging SD CT within 12 months were prospectively included to undergo a weight-based RD CT with MBIR. Radiation dose was recorded and tissue attenuation and image noise of four tissue types were measured. Reproducibility of target lesion size measurements of up to 5 target lesions per patient were analyzed. Subjective image quality was evaluated for three readers independently utilizing 4- or 5-point Likert scales.Median radiation dose reduction was 46% using RD CT (P < 0.01). Median image noise across all measured tissue types was lower (P < 0.01) in RD CT. Subjective image quality for RD CT was higher (P < 0.01) in regard to image noise and overall image quality; however, there was no statistically significant difference regarding image sharpness (P = 0.59). There were subjectively more artifacts on RD CT (P < 0.01). Lesion conspicuity was subjectively better in RD CT (P < 0.01). Repeated target lesion size measurements were highly reproducible both on SD CT (ICC = 0.987) and RD CT (ICC = 0.97).RD CT imaging with MBIR provides diagnostic imaging quality and comparable lesion conspicuity on follow-up exams while allowing dose reduction by a median of 46% compared to SD CT imaging.

    View details for DOI 10.1007/s00261-017-1140-5

    View details for PubMedID 28417170

  • Perfusion CT measurements predict tumor response in rectal carcinoma ABDOMINAL RADIOLOGY Kino, A., Shaffer, J., Maturen, K. E., Schmiedeskamp, H., Koong, A. C., Chang, D. T., Fleischmann, D., Kamaya, A. 2017; 42 (4): 1132-1140
  • Doppler Ultrasound in Liver Cirrhosis: Correlation of Hepatic Artery and Portal Vein Measurements With Model for End-Stage Liver Disease Score JOURNAL OF ULTRASOUND IN MEDICINE Park, H. S., Desser, T. S., Jeffrey, R. B., Kamaya, A. 2017; 36 (4): 725-730


    To determine whether hepatic arterial and portal venous Doppler ultrasound measurements of the liver in cirrhotic patients correlate with patients' Model for End-Stage Liver Disease (MELD) scores, splenomegaly, or ascites.Sonographic images and reports were reviewed of 264 patients with hepatic cirrhosis who underwent abdominal ultrasound with Doppler in this internal review board-approved retrospective study. MELD scores were recorded at the time of ultrasound. On gray-scale ultrasound, spleen length was measured and the presence of ascites was noted. Hepatic arterial velocity (HAv) with angle correction, hepatic arterial resistive index, and portal vein velocity with angle correction were measured on Doppler ultrasound. Correlation of hepatic arterial and portal venous Doppler values with MELD score, presence of splenomegaly, and presence of ascites was tested using linear or binary logistic regression analysis. Diagnostic performance of Doppler parameters for high-risk MELD was assessed.The HAv statistically significantly correlated with the MELD score (P?=?.0001), spleen size (P =.027), and presence of ascites (P =.0001), whereas the hepatic arterial resistive index and portal vein velocity did not correlate with these factors. For MELD scores greater than 19, an HAv greater than 120 cm/s showed accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of 74, 42, 90, 67, and 76%, respectively. With an HAv greater than 160 cm/s, the odds ratio for MELD scores greater than 19 was 42.1.We found a statistically significant correlation with elevated HAv and increasing MELD scores, splenomegaly, and presence of ascites in patients with cirrhotic liver disease; this may be a useful imaging biomarker in the evaluation of patients with cirrhosis.

    View details for DOI 10.7863/ultra.16.03107

    View details for Web of Science ID 000397505800006

  • Chapter 5 Ultrasound Characteristics of Benign vs Malignant Cervical Lymph Nodes. Seminars in ultrasound, CT, and MR Prativadi, R., Dahiya, N., Kamaya, A., Bhatt, S. 2017; 38 (5): 506?15


    With approximately 800 lymph nodes in the body, and more than one-third found within the head and neck, lymph nodes are a common site for neck pathology. Differentiation between benign and malignant lymph nodes is critical in accurate prognosis; similarly, treatment hinges on accurate identification of the etiology of the pathologic process. Key gray-scale and color Doppler ultrasound criteria can help accurately distinguish between benign and malignant lymph nodes.

    View details for PubMedID 29031367

  • US LI-RADS: ultrasound liver imaging reporting and data system for screening and surveillance of hepatocellular carcinoma. Abdominal radiology (New York) Morgan, T. A., Maturen, K. E., Dahiya, N., Sun, M. R., Kamaya, A. 2017


    Ultrasound is the most widely used imaging tool for hepatocellular carcinoma (HCC) screening and surveillance. Until now, this method has lacked standardized guidelines for interpretation, reporting, and management recommendations [1-5]. To address this need, the American College of Radiology (ACR) has developed the Ultrasound Liver Imaging Reporting and Data System (US LI-RADS) algorithm. The proposed algorithm has two components: detection scores and visualization scores. The detection score guides management and has three categories: US-1 Negative, US-2 Subthreshold, and US-3 Positive. The visualization score informs the expected sensitivity of the ultrasound examination and also has three categories: Visualization A: No or minimal limitations; Visualization B: Moderate limitations; and Visualization C: Severe limitations. Standardization in ultrasound utilization, reporting, and management in high-risk individuals has the capacity to improve communication with patients and referring physicians, unify screening and surveillance algorithms, impact outcomes, and supply quantitative data for future research.

    View details for PubMedID 28936543

  • Screening and Surveillance of Hepatocellular Carcinoma: An Introduction to Ultrasound Liver Imaging Reporting and Data System. Radiologic clinics of North America Fetzer, D. T., Rodgers, S. K., Harris, A. C., Kono, Y., Wasnik, A. P., Kamaya, A., Sirlin, C. 2017; 55 (6): 1197?1209


    Given the high prevalence, increasing incidence, and significant morbidity and mortality related to hepatocellular carcinoma (HCC), a robust and cost-effective screening and surveillance program is needed. Most societies recommend ultrasound for HCC screening, despite lack of standardization in imaging acquisition, reporting content and language, and follow-up recommendations. The American College of Radiology Ultrasound Liver Imaging Reporting and Data System (US LI-RADS) fills this unmet need by providing standardization in the use of US in at-risk patients. It is anticipated that US LI-RADS will improve the performance of ultrasound for HCC screening and surveillance and unify management recommendations.

    View details for PubMedID 28991560

  • MR Imaging-Pathologic Correlation in Ovarian Cancer. Magnetic resonance imaging clinics of North America Stein, E. B., Wasnik, A. P., Sciallis, A. P., Kamaya, A., Maturen, K. E. 2017; 25 (3): 545?62


    There are many ovarian cancer subtypes, giving rise to a range of appearances at gross pathology and magnetic resonance (MR) imaging. Certain fundamental concepts at MR, arising from underlying tissue characteristics, can provide guidance to radiologists in suggesting a diagnosis. The ability of multiparametric MR to risk stratify ovarian masses can contribute substantially to clinical decision making and patient management.

    View details for PubMedID 28668159

  • Epidemiology of hepatocellular carcinoma: target population for surveillance and diagnosis. Abdominal radiology (New York) Tang, A., Hallouch, O., Chernyak, V., Kamaya, A., Sirlin, C. B. 2017


    Hepatocellular carcinoma (HCC) is the sixth most common cancer and the second leading cause of cancer mortality worldwide. Incidence rates of liver cancer vary widely between geographic regions and are highest in Eastern Asia and sub-Saharan Africa. In the United States, the incidence of HCC has increased since the 1980s. HCC detection at an early stage through surveillance and curative therapy has considerably improved the 5-year survival. Therefore, medical societies advocate systematic screening and surveillance of target populations at particularly high risk for developing HCC to facilitate early-stage detection. Risk factors for HCC include cirrhosis, chronic infection with hepatitis B virus (HBV), hepatitis C virus (HCV), excess alcohol consumption, non-alcoholic fatty liver disease, family history of HCC, obesity, type 2 diabetes mellitus, and smoking. Medical societies utilize risk estimates to define target patient populations in which imaging surveillance is recommended (risk above threshold) or in which the benefits of surveillance are uncertain (risk unknown or below threshold). All medical societies currently recommend screening and surveillance in patients with cirrhosis and subsets of patients with chronic HBV; some societies also include patients with stage 3 fibrosis due to HCV as well as additional groups. Thus, target population definitions vary between regions, reflecting cultural, demographic, economic, healthcare priority, and biological differences. The Liver Imaging Reporting and Data System (LI-RADS) defines different patient populations for surveillance and for diagnosis and staging. We also discuss general trends pertaining to geographic region, age, gender, ethnicity, impact of surveillance on survival, mortality, and future trends.

    View details for PubMedID 28647765

  • Imaging Anatomy: Ultrasound Woodward, P. J., Griffith, J. F., Ahuja, A. T., Kamaya, A., Wong-You-Cheong, J. Elsevier. 2017
  • Benign Gynecologic Conditions of the Uterus. Magnetic resonance imaging clinics of North America Kassam, Z., Petkovska, I., Wang, C. L., Trinh, A. M., Kamaya, A. 2017; 25 (3): 577?600


    In this article, the authors review the anatomy, pathophysiology, MR imaging features, and diagnostic criteria for benign uterine conditions, including adenomyosis, uterine leiomyomas, retained products of conception, and uterine arteriovenous malformations. Pearls, pitfalls, and variants are discussed for each entity as well as important imaging features that can affect management decisions.

    View details for PubMedID 28668161

  • Toward Automated Pre-Biopsy Thyroid Cancer Risk Estimation in Ultrasound. AMIA ... Annual Symposium proceedings. AMIA Symposium Galimzianova, A., Siebert, S. M., Kamaya, A., Desser, T. S., Rubin, D. L. 2017; 2017: 734?41


    We propose a computational framework for automated cancer risk estimation of thyroid nodules visualized in ultrasound (US) images. Our framework estimates the probability of nodule malignancy using random forests on a rich set of computational features. An expert radiologist annotated thyroid nodules in 93 biopsy-confirmed patients using semantic image descriptors derived from standardized lexicon. On our dataset, the AUC of the proposed method was 0.70, which was comparable to five baseline expert annotation-based classifiers with AUC values from 0.72 to 0.81. Moreover, the use of the framework for decision making on nodule biopsy could have spared five out of 46 benign nodule biopsies at no cost to the health of patients with malignancies. Our results confirm the feasibility of computer-aided tools for noninvasive malignancy risk estimation in patients with thyroid nodules that could help to decrease the number of unnecessary biopsies and surgeries.

    View details for PubMedID 29854139

  • Noninvasive radiomics signature based on quantitative analysis of computed tomography images as a surrogate for microvascular invasion in hepatocellular carcinoma: a pilot study. Journal of medical imaging (Bellingham, Wash.) Bakr, S., Echegaray, S., Shah, R., Kamaya, A., Louie, J., Napel, S., Kothary, N., Gevaert, O. 2017; 4 (4): 041303


    We explore noninvasive biomarkers of microvascular invasion (mVI) in patients with hepatocellular carcinoma (HCC) using quantitative and semantic image features extracted from contrast-enhanced, triphasic computed tomography (CT). Under institutional review board approval, we selected 28 treatment-naive HCC patients who underwent surgical resection. Four radiologists independently selected and delineated tumor margins on three axial CT images and extracted computational features capturing tumor shape, image intensities, and texture. We also computed two types of "delta features," defined as the absolute difference and the ratio computed from all pairs of imaging phases for each feature. 717 arterial, portal-venous, delayed single-phase, and delta-phase features were robust against interreader variability ([Formula: see text]). An enhanced cross-validation analysis showed that combining robust single-phase and delta features in the arterial and venous phases identified mVI (AUC [Formula: see text]). Compared to a previously reported semantic feature signature (AUC 0.47 to 0.58), these features in our cohort showed only slight to moderate agreement (Cohen's kappa range: 0.03 to 0.59). Though preliminary, quantitative analysis of image features in arterial and venous phases may be potential surrogate biomarkers for mVI in HCC. Further study in a larger cohort is warranted.

    View details for PubMedID 28840174

  • The utility of hepatic artery velocity in diagnosing patients with acute cholecystitis. Abdominal radiology (New York) Loehfelm, T. W., Tse, J. R., Jeffrey, R. B., Kamaya, A. 2017


    To test the diagnostic performance of elevated peak systolic hepatic arterial velocity (HAv) in the diagnosis of acute cholecystitis.229 patients with an ultrasound (US) performed for right upper quadrant (RUQ) pain were retrospectively reviewed. 35 had cholecystectomy within 10 days of ultrasound and were included as test subjects. 47 had normal US and serology and were included as controls. Each test patient US was reviewed for the presence of gallstones, gallbladder distention, sludge, echogenic pericholecystic fat, pericholecystic fluid, gallbladder wall thickening, gallbladder wall hyperemia, and reported sonographic Murphy sign. Demographic, clinical, and hepatic artery parameters at time of original imaging were recorded. Acute cholecystitis at pathology was the primary outcome variable.21 patients had acute cholecystitis and 14 had chronic cholecystitis by pathology. For patients who went to cholecystectomy, HAv ?100 cm/s to diagnose acute cholecystitis was more accurate (69%) than the original radiology report (63%), the presence of gallstones (51%), and sonographic Murphy sign (50%). Statistically significant predictors of acute cholecystitis included HAv ?100 cm/s (p = 0.008), older age (p = 0.012), and elevated WBC (p = 0.002), while gallstones (p = 0.077), hepatic artery resistive index (HARI) (p = 0.199), gallbladder distension (p = 0.252), sludge (p = 0.147), echogenic fat (p = 0.184), pericholecystic fluid (p = 0.357), wall thickening (p = 0.434), hyperemia (p = 0.999), and sonographic Murphy sign (p = 0.765) were not significantly correlated with acute cholecystitis compared to chronic cholecystitis.HAv ?100 cm/s is a useful objective parameter that may improve the performance of US in the diagnosis of acute cholecystitis.

    View details for PubMedID 28840272

  • Clinical and imaging predictors of management in retained products of conception ABDOMINAL RADIOLOGY Kamaya, A., Krishnarao, P. M., Nayak, N., Jeffrey, R. B., Maturen, K. E. 2016; 41 (12): 2429-2434


    To determine if clinical and ultrasound (US) imaging features help predict management in clinically suspected retained products of conception (RPOC).334 patients sonographically evaluated for RPOC were included in this IRB-approved retrospective study. Of the 334 patients, 176 had sonographic diagnosis of RPOC and comprised the final study group. Patients were managed expectantly, medically, or surgically in accordance with clinical judgment of treating physicians. Pelvic sonograms were retrospectively reviewed for endometrial stripe thickness and vascularity was graded on a 0-3 scale based on appearance relative to myometrium (Grade 0: no vascularity, Grade 1: minimal vascularity, Grade 2: moderate vascularity, Grade 3: marked vascularity). Clinical and imaging predictors of management were evaluated in univariate and multivariate analysis.Mean patient age was 29.6 years and mean gestational age was 17.4 weeks. Most (74.4%) women presented with vaginal bleeding. 83 patients (47.2%) were treated conservatively with expectant management, 42 (23.8%) were treated medically, and 51 (29.0%) required surgical intervention. Mean endometrial stripe thickness was 21.3 mm. 47 women (26.7%) had vascularity score of 0; 50 (28.4%) had score 1; 52 (29.6%) had score 2; and 27 (15.3%) had score 3. In univariate analysis, serum hemoglobin (Hb) (p < 0.0001), endometrial stripe thickness on US (p < 0.005), presenting symptoms (p = 0.03), and US vascularity score (p < 0.005) were statistically significant predictors of final management. In multivariate logistic regression, serum Hb (OR 0.69, 95% CI 0.55-0.86, p < 0.0009), endometrial stripe thickness (OR 1.08, 95% CI 1.04-1.12, p < 0.0001), and US vascularity score (OR 1.77, 95% CI 1.16-2.70, p < 0.01) were statistically significant predictors of need for surgery.Serum Hb, endometrial stripe thickness, and US vascularity score were significant predictors of clinical management, particularly the need for surgical intervention, in women with clinically suspected RPOC.

    View details for DOI 10.1007/s00261-016-0954-x

    View details for Web of Science ID 000390050600015

    View details for PubMedID 27853850

  • Robotic intrafractional US guidance for liver SABR: System design, beam avoidance, and clinical imaging. Medical physics Schlosser, J., Gong, R. H., Bruder, R., Schweikard, A., Jang, S., Henrie, J., Kamaya, A., Koong, A., Chang, D. T., Hristov, D. 2016; 43 (11): 5951-?


    To present a system for robotic 4D ultrasound (US) imaging concurrent with radiotherapy beam delivery and estimate the proportion of liver stereotactic ablative body radiotherapy (SABR) cases in which robotic US image guidance can be deployed without interfering with clinically used VMAT beam configurations.The image guidance hardware comprises a 4D US machine, an optical tracking system for measuring US probe pose, and a custom-designed robot for acquiring hands-free US volumes. In software, a simulation environment incorporating the LINAC, couch, planning CT, and robotic US guidance hardware was developed. Placement of the robotic US hardware was guided by a target visibility map rendered on the CT surface by using the planning CT to simulate US propagation. The visibility map was validated in a prostate phantom and evaluated in patients by capturing live US from imaging positions suggested by the visibility map. In 20 liver SABR patients treated with VMAT, the simulation environment was used to virtually place the robotic hardware and US probe. Imaging targets were either planning target volumes (PTVs, range 5.9-679.5 ml) or gross tumor volumes (GTVs, range 0.9-343.4 ml). Presence or absence of mechanical interference with LINAC, couch, and patient body as well as interferences with treated beams was recorded.For PTV targets, robotic US guidance without mechanical interference was possible in 80% of the cases and guidance without beam interference was possible in 60% of the cases. For the smaller GTV targets, these proportions were 95% and 85%, respectively. GTV size (1/20), elongated shape (1/20), and depth (1/20) were the main factors limiting the availability of noninterfering imaging positions. The robotic US imaging system was deployed in two liver SABR patients during CT simulation with successful acquisition of 4D US sequences in different imaging positions.This study indicates that for VMAT liver SABR, robotic US imaging of a relevant internal target may be possible in 85% of the cases while using treatment plans currently deployed in the clinic. With beam replanning to account for the presence of robotic US guidance, intrafractional US may be an option for 95% of the liver SABR cases.

    View details for PubMedID 27806580

  • Sonographic Evaluation for Endometrial Polyps: The Interrupted Mucosa Sign. Journal of ultrasound in medicine Kamaya, A., Yu, P. C., Lloyd, C. R., Chen, B. H., Desser, T. S., Maturen, K. E. 2016; 35 (11): 2381-2387


    To evaluate the interrupted mucosa sign for identification of endometrial polyps, using pathologic confirmation as the reference standard, compared to other accepted sonographic findings.We reviewed 195 patients referred for pelvic sonographic evaluations for suspected endometrial polyps in this retrospective Institutional Review Board-approved study. Of these, 82 had tissue sampling of the endometrium and constituted the final study group. Patient data, including age, menopausal status, last menstrual period, and final pathologic diagnosis, were recorded. Sonograms were reviewed by 2 blinded board-certified radiologists for endometrial features, including thickness, echogenicity, vascularity, presence of a mass, and the interrupted mucosa sign. Descriptive statistics and multivariate logistic regression analysis were performed.The mean age of the patients was 44.99 (SD, 9.88) years, 79.1% of whom were premenopausal. Pathologic diagnosis confirmed polyps in 58 (70.73%). A single feeding vessel was visualized in 36 patients with polyps (62.07%), whereas the interrupted mucosa sign was visualized in 34 (58.62%). The presence of a feeding vessel, the interrupted mucosa sign, or both detected 48 (82.76%) of the polyps. In the multivariate analysis, only the interrupted mucosa sign was a statistically significant predictor of pathologic diagnosis of a polyp (P = .035), with an odds ratio of 3.83 (95% confidence interval, 1.10-13.29). Other sonographic findings were not independent predictors of a polyp: mass (P = .35), single feeding vessel (P = .31), endometrial thickness (P = .88), and endometrial echogenicity (P = .45). The sensitivity, specificity, and positive predictive value of the interrupted mucosa sign were 59%, 75%, and 85%, respectively.The interrupted mucosa sign is a promising sonographic sign for identification of endometrial polyps, with greater predictive power than previously described signs. It has the potential to improve the diagnostic performance of sonography, especially when used in combination with other described signs.

    View details for PubMedID 27629758

  • Ovarian cancer mimics: how to avoid being fooled by extraovarian pelvic masses ABDOMINAL RADIOLOGY Masch, W. R., Kamaya, A., Wasnik, A. P., Maturen, K. E. 2016; 41 (4): 783-793


    In our clinical experience, pelvic masses from a variety of anatomic sites may be misdiagnosed as ovarian cancer. This tendency to overdiagnose a rare disease probably reflects both its protean imaging appearance and concern for its potential morbidity and mortality. However, radiologists can better serve patients with an analytic approach to the anatomic and tissue features of pelvic masses. We review a range of ovarian cancer mimics and illustrate the radiologic reasoning enabling correct diagnosis.

    View details for DOI 10.1007/s00261-015-0570-1

    View details for Web of Science ID 000374964100020

    View details for PubMedID 26867729

  • Duplex Doppler Ultrasound of the Hepatic Artery: A Window to Diagnosis of Diffuse Liver Pathology. Ultrasound quarterly Go, S., Kamaya, A., Jeffrey, B., Desser, T. S. 2016; 32 (1): 58-66


    The use of Doppler sonography for evaluation of the liver is well established, and evaluation of the portal and hepatic veins in native livers, as well as the hepatic artery in transplant livers, is a standard part of the examination. Less well known, however, is that assessment hepatic of artery blood flow velocities and waveforms can permit inferences to be made about liver and system pathophysiology even in native livers. This review will illustrate that hepatic parenchymal abnormalities, as well as primary vascular abnormalities both upstream and downstream of the proper hepatic artery, can be inferred from careful interrogation of its Doppler signature during routine abdominal sonography.

    View details for DOI 10.1097/RUQ.0000000000000166

    View details for PubMedID 26938035

  • Radiological findings in pelvic solitary fibrous tumour. BJR case reports Johannet, P., Kamaya, A., Gayer, G. 2016; 2 (4): 20150373


    Solitary fibrous tumour (SFT) is an uncommon, usually benign mesenchymal neoplasm. SFT was first described in the pleura, but has subsequently been reported to occur in numerous anatomic locations including the abdomen and pelvis. Abdominopelvic SFTs are typically an indolent process, in spite of reaching a large size by the time of diagnosis. The preferred treatment is complete resection followed by extended follow-up surveillance. The risk of local recurrence and metastasis correlates with tumour size and the histological status of surgical margins. We present the imaging findings of a large pelvic SFT in a 61-year-old female, including ultrasound, CT and MRI.

    View details for PubMedID 30460023

  • Diagnostic Ultrasound: Abdomen and Pelvis Kamaya, A., Wong-You-Cheong, J. Elsevier. 2016
  • Sonographic Detection of Extracapsular Extension in Papillary Thyroid Cancer. Journal of ultrasound in medicine Kamaya, A., Tahvildari, A. M., Patel, B. N., Willmann, J. K., Jeffrey, R. B., Desser, T. S. 2015; 34 (12): 2225-2230


    To identify and evaluate sonographic features suggestive of extracapsular extension in papillary thyroid cancer.Three board-certified radiologists blinded to the final pathologic tumor stage reviewed sonograms of pathologically proven cases of papillary thyroid cancer for the presence of extracapsular extension. The radiologists evaluated the following features: capsular abutment, bulging of the normal thyroid contour, loss of the echogenic capsule, and vascularity extending beyond the capsule.A total of 129 cases of pathologically proven thyroid cancer were identified. Of these, 51 were excluded because of lack of preoperative sonography, and 16 were excluded because of pathologic findings showing anaplastic carcinoma, follicular carcinoma, or microcarcinoma (<10 mm). The final analysis group consisted of 62 patients with papillary thyroid carcinoma, 16 of whom had pathologically proven extracapsular extension. The presence of capsular abutment had 100% sensitivity for detection of extracapsular extension. Conversely, lack of capsular abutment had a 100% negative predictive value (NPV) for excluding extracapsular extension. Contour bulging had 88% sensitivity for detection of extracapsular extension and when absent had an 87% NPV. Loss of the echogenic capsule was the best predictor of the presence of extracapsular extension, with an odds ratio of 10.23 (P= .034). This sonographic finding had 75% sensitivity, 65% specificity, and an 88% NPV. Vascularity beyond the capsule had 89% specificity but sensitivity of only 25%.Sonographic features of capsular abutment, contour bulging, and loss of the echogenic thyroid capsule have excellent predictive value for excluding or detecting extracapsular extension and may help in biopsy selection, surgical planning, and treatment of patients with papillary thyroid cancer.

    View details for DOI 10.7863/ultra.15.02006

    View details for PubMedID 26518279

  • Variable color Doppler sonographic appearances of retained products of conception: radiologic-pathologic correlation. Abdominal imaging Kamaya, A., Krishnarao, P. M., Folkins, A. K., Jeffrey, R. B., Desser, T. S., Maturen, K. E. 2015; 40 (7): 2683-2689


    Retained products of conception (RPOC) displays variable vascularity, ranging from avascular to markedly vascular on color Doppler sonography. We hypothesize that variability in sonographic vascularity may be due to histopathologic variation in the placental tissue.After institutional review board approval, sonographic images and pathologic specimens were retrospectively reviewed in 26 patients with pathologically proven RPOC. Ultrasound (US) images were scored 0-3 for the degree of vascularity by two radiologists blinded to the diagnosis. Corresponding pathologic specimens were evaluated for vascularization of chorionic villi, degree of inflammation, morphology of maternal arteries, chorionic villous preservation, and percentage of clot, membranes, chorionic villi, and decidua/myometrium. Statistical analysis, including multiple linear regression, was performed.RPOC with histologically avascular chorionic villi or those with markedly reduced vascularization had significantly lower US vascularity scores (p = 0.030) than those with chorionic villi showing normal or decreased vascularization. Sonographically avascular RPOC had a significantly lower percentage villi (p = 0.028) and higher percentage of decidua (p = 0.004) than specimens where US showed any Doppler vascularity. Histologic vascularity of villi (p = 0.049) and non-observation of maternal arteries (p = 0.001) were significant predictors of US vascularity scores in multivariate linear regression analysis, while inflammation of villi (p = 0.053) was a marginally significant predictor.Histologic vascularity of villi appears to contribute to the observed variation in sonographic vascularity. This finding may underlie known differences in clinical outcomes between sonographic vascularity groups.

    View details for DOI 10.1007/s00261-015-0424-x

    View details for PubMedID 25862548

  • Core samples for radiomics features that are insensitive to tumor segmentation: method and pilot study using CT images of hepatocellular carcinoma. Journal of medical imaging (Bellingham, Wash.) Echegaray, S., Gevaert, O., Shah, R., Kamaya, A., Louie, J., Kothary, N., Napel, S. 2015; 2 (4): 041011-?


    The purpose of this study is to investigate the utility of obtaining "core samples" of regions in CT volume scans for extraction of radiomic features. We asked four readers to outline tumors in three representative slices from each phase of multiphasic liver CT images taken from 29 patients (1128 segmentations) with hepatocellular carcinoma. Core samples were obtained by automatically tracing the maximal circle inscribed in the outlines. Image features describing the intensity, texture, shape, and margin were used to describe the segmented lesion. We calculated the intraclass correlation between the features extracted from the readers' segmentations and their core samples to characterize robustness to segmentation between readers, and between human-based segmentation and core sampling. We conclude that despite the high interreader variability in manually delineating the tumor (average overlap of 43% across all readers), certain features such as intensity and texture features are robust to segmentation. More importantly, this same subset of features can be obtained from the core samples, providing as much information as detailed segmentation while being simpler and faster to obtain.

    View details for DOI 10.1117/1.JMI.2.4.041011

    View details for PubMedID 26587549

  • Atypia of undetermined significance and follicular lesions of undetermined significance: sonographic assessment for prediction of the final diagnosis. Journal of ultrasound in medicine Kamaya, A., Lewis, G. H., Liu, Y., Akatsu, H., Kong, C., Desser, T. S. 2015; 34 (5): 767-774


    To determine whether radiologic assessment of thyroid nodules can potentially help guide clinical management after a cytologic diagnosis of atypia of undetermined significance or a follicular lesion of undetermined significance.We identified 41 patients with 41 thyroid nodules initially diagnosed as atypia or follicular lesions of undetermined significance on fine-needle aspiration that were subsequently definitively diagnosed by either surgical resection or repeated fine-needle aspiration. All sonograms of nodules were reviewed by 2 blinded board-certifiedradiologists. Lesions were assessed in 3 ways: (1) Mayo pattern classification as benign, indeterminate, or worrisome for malignancy (Ultrasound Q 2005; 21:157-165); (2) thyroid imaging reporting and data system scores (scale of 1-5) based on 2 different previously published scoring criteria (Park et al [Thyroid 2009; 19:1257-1264] and Kwak et al [Radiology 2011; 260:892-899]); and (3) binary classification as benign or malignant.Of the 41 nodules, 25 had benign histologic findings, and 16 were malignant. Mayo pattern classification was 100% accurate for the benign score. Lesions with a Mayo score of indeterminate were malignant in 21% of cases (6 of 28) and benign in 79% (22 of 28). Lesions with a Mayo score of malignant were malignant in 91% of cases (10 of 11) and benign in 9% (1 of 11). Thyroid imaging reporting and data system scores had area under the receiver operating characteristic curve values of 0.827 for Park scores and 0.822 for Kwak scores. Radiologist binary classification of thyroid nodules showed 88% overall accuracy.Radiologist assessment of thyroid nodules in cases of atypia of undetermined significance or follicular lesions of undetermined significance is highly predictive of the final diagnosis and can help guide management of thyroid nodules of these pathologic types.

    View details for DOI 10.7863/ultra.34.5.767

    View details for PubMedID 25911708

  • Classification of Hypervascular Liver Lesions Based on Hepatic Artery and Portal Vein Blood Supply Coefficients Calculated from Triphasic CT Scans JOURNAL OF DIGITAL IMAGING Boas, F. E., Kamaya, A., Do, B., Desser, T. S., Beaulieu, C. F., Vasanawala, S. S., Hwang, G. L., Sze, D. Y. 2015; 28 (2): 213-223


    Perfusion CT of the liver typically involves scanning the liver at least 20 times, resulting in a large radiation dose. We developed and validated a simplified model of tumor blood supply that can be applied to standard triphasic scans and evaluated whether this can be used to distinguish benign and malignant liver lesions. Triphasic CTs of 46 malignant and 32 benign liver lesions were analyzed. For each phase, regions of interest were drawn in the arterially enhancing portion of each lesion, as well as the background liver, aorta, and portal vein. Hepatic artery and portal vein blood supply coefficients for each lesion were then calculated by expressing the enhancement curve of the lesion as a linear combination of the enhancement curves of the aorta and portal vein. Hepatocellular carcinoma (HCC) and hypervascular metastases, on average, both had increased hepatic artery coefficients compared to the background liver. Compared to HCC, benign lesions, on average, had either a greater hepatic artery coefficient (hemangioma) or a greater portal vein coefficient (focal nodular hyperplasia or transient hepatic attenuation difference). Hypervascularity with washout is a key diagnostic criterion for HCC, but it had a sensitivity of 72 % and specificity of 81 % for diagnosing malignancy in our diverse set of liver lesions. The sensitivity for malignancy was increased to 89 % by including enhancing lesions that were hypodense on all phases. The specificity for malignancy was increased to 97 % (p?=?0.039) by also examining hepatic artery and portal vein blood supply coefficients, while maintaining a sensitivity of 76 %.

    View details for DOI 10.1007/s10278-014-9725-9

    View details for Web of Science ID 000351242500012

    View details for PubMedID 25183580

  • Atypical thyroid cancers on sonography. Ultrasound quarterly Klang, K., Kamaya, A., Tahvildari, A. M., Jeffrey, R. B., Desser, T. S. 2015; 31 (1): 69-74


    The management of thyroid nodules is a common clinical problem. Thyroid nodules are present in up to 50% of the adult population. However, thyroid malignancy is rare, occurring in only 5% to 15% of nodules. Although certain specific patterns on imaging are almost always indicative of benignity, there is considerable overlap between the sonographic appearances of benign and malignant nodules. Radiologists should be wary of applying pattern recognition approaches too liberally as some malignant nodules may exhibit sonographic features more commonly associated with benign nodules such as cystic change, comet-tail artifact, smooth margins, echogenic echotexture, hypoechoic halos, or peripheral calcifications. This article illustrates atypical imaging appearances of thyroid malignancies and reviews recent literature in an attempt to clarify nuances in the diagnosis of malignancy in benign-appearing nodules.

    View details for DOI 10.1097/RUQ.0000000000000079

    View details for PubMedID 25706368

  • Single-versus Multifraction Stereotactic Body Radiation Therapy for Pancreatic Adenocarcinoma: Outcomes and Toxicity INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS Pollom, E. L., Alagappan, M., von Eyben, R., Kunz, P. L., Fisher, G. A., Ford, J. A., Poultsides, G. A., Visser, B. C., Norton, J. A., Kamaya, A., Cox, V. L., Columbo, L. A., Koong, A. C., Chang, D. T. 2014; 90 (4): 918-925


    We report updated outcomes of single- versus multifraction stereotactic body radiation therapy (SBRT) for unresectable pancreatic adenocarcinoma.We included 167 patients with unresectable pancreatic adenocarcinoma treated at our institution from 2002 to 2013, with 1-fraction (45.5% of patient) or 5-fraction (54.5% of patients) SBRT. The majority of patients (87.5%) received chemotherapy.Median follow-up was 7.9 months (range: 0.1-63.6). The 6- and 12-month cumulative incidence rates (CIR) of local recurrence for patients treated with single-fraction SBRT were 5.3% (95% confidence interval [CI], 0.2%-10.4%) and 9.5% (95% CI, 2.7%-16.2%), respectively. The 6- and 12-month CIR with multifraction SBRT were 3.4% (95% CI, 0.0-7.2%) and 11.7% (95% CI, 4.8%-18.6%), respectively. Median survival from diagnosis for all patients was 13.6 months (95% CI, 12.2-15.0 months). The 6- and 12- month survival rates from SBRT for the single-fraction group were 67.0% (95% CI, 57.2%-78.5%) and 30.8% (95% CI, 21.9%-43.6%), respectively. The 6- and 12- month survival rates for the multifraction group were 75.7% (95% CI, 67.2%-85.3%) and 34.9% (95% CI, 26.1%-46.8%), respectively. There were no differences in CIR or survival rates between the single- and multifraction groups. The 6- and 12-month cumulative incidence rates of gastrointestinal toxicity grade ?3 were 8.1% (95% CI, 1.8%-14.4%) and 12.3% (95% CI, 4.7%-20.0%), respectively, in the single-fraction group, and both were 5.6% (95% CI, 0.8%-10.5%) in the multifraction group. There were significantly fewer instances of toxicity grade ?2 with multifraction SBRT (P=.005). Local recurrence and toxicity grade ?2 were independent predictors of worse survival.Multifraction SBRT for pancreatic cancer significantly reduces gastrointestinal toxicity without compromising local control.

    View details for DOI 10.1016/j.ijrobp.2014.06.066

    View details for Web of Science ID 000344734300029

  • Single- versus multifraction stereotactic body radiation therapy for pancreatic adenocarcinoma: outcomes and toxicity. International journal of radiation oncology, biology, physics Pollom, E. L., Alagappan, M., von Eyben, R., Kunz, P. L., Fisher, G. A., Ford, J. A., Poultsides, G. A., Visser, B. C., Norton, J. A., Kamaya, A., Cox, V. L., Columbo, L. A., Koong, A. C., Chang, D. T. 2014; 90 (4): 918-925


    We report updated outcomes of single- versus multifraction stereotactic body radiation therapy (SBRT) for unresectable pancreatic adenocarcinoma.We included 167 patients with unresectable pancreatic adenocarcinoma treated at our institution from 2002 to 2013, with 1-fraction (45.5% of patient) or 5-fraction (54.5% of patients) SBRT. The majority of patients (87.5%) received chemotherapy.Median follow-up was 7.9 months (range: 0.1-63.6). The 6- and 12-month cumulative incidence rates (CIR) of local recurrence for patients treated with single-fraction SBRT were 5.3% (95% confidence interval [CI], 0.2%-10.4%) and 9.5% (95% CI, 2.7%-16.2%), respectively. The 6- and 12-month CIR with multifraction SBRT were 3.4% (95% CI, 0.0-7.2%) and 11.7% (95% CI, 4.8%-18.6%), respectively. Median survival from diagnosis for all patients was 13.6 months (95% CI, 12.2-15.0 months). The 6- and 12- month survival rates from SBRT for the single-fraction group were 67.0% (95% CI, 57.2%-78.5%) and 30.8% (95% CI, 21.9%-43.6%), respectively. The 6- and 12- month survival rates for the multifraction group were 75.7% (95% CI, 67.2%-85.3%) and 34.9% (95% CI, 26.1%-46.8%), respectively. There were no differences in CIR or survival rates between the single- and multifraction groups. The 6- and 12-month cumulative incidence rates of gastrointestinal toxicity grade ?3 were 8.1% (95% CI, 1.8%-14.4%) and 12.3% (95% CI, 4.7%-20.0%), respectively, in the single-fraction group, and both were 5.6% (95% CI, 0.8%-10.5%) in the multifraction group. There were significantly fewer instances of toxicity grade ?2 with multifraction SBRT (P=.005). Local recurrence and toxicity grade ?2 were independent predictors of worse survival.Multifraction SBRT for pancreatic cancer significantly reduces gastrointestinal toxicity without compromising local control.

    View details for DOI 10.1016/j.ijrobp.2014.06.066

    View details for PubMedID 25585785

  • CT Perfusion of the Liver: Principles and Applications in Oncology. Radiology Kim, S. H., Kamaya, A., Willmann, J. K. 2014; 272 (2): 322-344


    With the introduction of molecularly targeted chemotherapeutics, there is an increasing need for defining new response criteria for therapeutic success because use of morphologic imaging alone may not fully assess tumor response. Computed tomographic (CT) perfusion imaging of the liver provides functional information about the microcirculation of normal parenchyma and focal liver lesions and is a promising technique for assessing the efficacy of various anticancer treatments. CT perfusion also shows promising results for diagnosing primary or metastatic tumors, for predicting early response to anticancer treatments, and for monitoring tumor recurrence after therapy. Many of the limitations of early CT perfusion studies performed in the liver, such as limited coverage, motion artifacts, and high radiation dose of CT, are being addressed by recent technical advances. These include a wide area detector with or without volumetric spiral or shuttle modes, motion correction algorithms, and new CT reconstruction technologies such as iterative algorithms. Although several issues related to perfusion imaging-such as paucity of large multicenter trials, limited accessibility of perfusion software, and lack of standardization in methods-remain unsolved, CT perfusion has now reached technical maturity, allowing for its use in assessing tumor vascularity in larger-scale prospective clinical trials. In this review, basic principles, current acquisition protocols, and pharmacokinetic models used for CT perfusion imaging of the liver are described. Various oncologic applications of CT perfusion of the liver are discussed and current challenges, as well as possible solutions, for CT perfusion are presented. © RSNA, 2014 Online supplemental material is available for this article.

    View details for DOI 10.1148/radiol.14130091

    View details for PubMedID 25058132

  • A multicenter phase II study of pazopanib in patients with advanced gastrointestinal stromal tumors (GIST) following failure of at least imatinib and sunitinib. Annals of oncology Ganjoo, K. N., Villalobos, V. M., Kamaya, A., Fisher, G. A., Butrynski, J. E., Morgan, J. A., Wagner, A. J., D'adamo, D., McMillan, A., Demetri, G. D., George, S. 2014; 25 (1): 236-240


    Advanced GISTs are incurable, but often treatable for years with tyrosine kinase inhibitors (TKIs). The majority of GISTs harbor an oncogenic activating mutation in KIT or PDGFRA. Inhibition of this activating mutation with TKIs most often leads to durable disease control for many patients. However, almost all patients develop resistance to these TKIs, typically due to the development of secondary mutations, heralding the need for new therapeutic options. We conducted a phase II study evaluating the efficacy and toxicity of pazopanib, a broad spectrum TKI inhibiting KIT, VEGFRs (-1, -2, and -3), and PDGFR (-? and-?) in patients with advanced GIST following failure of at least imatinib and sunitinib.Patients received pazopanib 800 mg orally once daily. All patients were assessed for efficacy with CT scans every 8 weeks (two cycles). Patients continued pazopanib until progression or unacceptable toxicity. The primary end point was the 24-week nonprogression [complete response+partial response+stable disease (SD)] rate (NPR) per RECIST 1.1. Secondary end points included PFS, OS, and toxicity.Between August 2011 and September 2012, a total of 25 patients were treated at two institutions. Median number of prior therapy was 3 (range 2-7). A total of 90 cycles of pazopanib were administered, with a median of two cycles (range 1 to 17+) per patient. Best response of SD at any time was observed in 12 (48%) patients. The NPR was 17% [95% confidence interval (CI) 4.5-37]. All but one patient discontinued protocol either due to PD (n = 19) or intolerance (n = 4). One patient with succinate dehydrogenase (SDH)-deficient GIST exhibited continuing disease control after 17 cycles. The median PFS for the entire cohort was 1.9 months (95% CI 1.6-5.2), and the median OS was 10.7 months (95% CI 3.9-NR).Pazopanib was reasonably well tolerated with no unexpected toxicities. Pazopanib as a single agent has marginal activity in unselected heavily pretreated patients with advanced GIST.

    View details for DOI 10.1093/annonc/mdt484

    View details for PubMedID 24356634

  • The elusive parathyroid adenoma: techniques for detection. Ultrasound quarterly Devcic, Z., Jeffrey, R. B., Kamaya, A., Desser, T. S. 2013; 29 (3): 179-187


    The success of minimally invasive surgery for hyperparathyroidism depends on accurate preoperative localization of the hyperfunctioning adenoma with imaging. Ultrasound is an excellent initial modality because it has a high positive predictive value, sensitivity, and specificity, while being inexpensive and noninvasive without use of ionizing radiation. Determining the exact location and number of adenomas is essential, because these factors guide the surgical approach. The goal of this review article was to discuss specific sonographic techniques that can be applied to find even the elusive adenoma, which include (1) compression scanning, (2) color Doppler, (3) scanning regions where ectopic glands may be located, and (4) evaluating intrathyroidal adenomas.

    View details for DOI 10.1097/RUQ.0b013e3182a1ba6f

    View details for PubMedID 23975046

  • Photoacoustic imaging of the bladder: a pilot study. Journal of ultrasound in medicine Kamaya, A., Vaithilingam, S., Chung, B. I., Oralkan, O., Khuri-Yakub, B. T. 2013; 32 (7): 1245-1250


    Photoacoustic imaging is a promising new technology that combines tissue optical characteristics with ultrasound transmission and can potentially visualize tumor depth in bladder cancer. We imaged simulated tumors in 5 fresh porcine bladders with conventional pulse-echo sonography and photoacoustic imaging. Isoechoic biomaterials of different optical qualities were used. In all 5 of the bladder specimens, photoacoustic imaging showed injected biomaterials, containing varying degrees of pigment, better than control pulse-echo sonography. Photoacoustic imaging may be complementary to diagnostic information obtained by cystoscopy and urine cytologic analysis and could potentially obviate the need for biopsy in some tumors before definitive treatment.

    View details for DOI 10.7863/ultra.32.7.1245

    View details for PubMedID 23804347

  • New Technologies in Clinical Ultrasound SEMINARS IN ROENTGENOLOGY Kamaya, A., Machtaler, S., Sanjani, S. S., Nikoozadeh, A., Sommer, F. G., Khuri-Yakub, B. T., Willmann, J. K., Desser, T. S. 2013; 48 (3): 214-223
  • Pitfalls in sonographic evaluation of thyroid abnormalities. Seminars in ultrasound, CT, and MR Patel, B. N., Kamaya, A., Desser, T. S. 2013; 34 (3): 226-235


    Ultrasound of the thyroid has become increasingly common, with evaluation of thyroid nodules representing the main indication for its use. While detection of thyroid nodules with modern high-resolution sonographic equipment is generally not a challenge, pitfalls may occur by which normal structures or pathology in neighboring organs are mistaken for thyroid nodules. Numerous reports in the literature describe various sonographic features of nodules in an attempt to stratify lesions into benign or malignant categories. While neither nodule size nor number is reliable, echogenicity, microcalcifcation, shape, and composition have been reported to be helpful in classifying thyroid nodules. No single feature should be used in isolation, and consensus guidelines have been established as to when fine-needle aspiration is indicated. Pitfalls remain in the evaluation of thyroid nodules demonstrating atypical features, such as cystic papillary carcinomas. Focal presentation of typically diffuse processes, such as Graves' disease and Hashimoto thyroiditis, may mimic malignant nodules, but carcinomas occur in these settings as well as in a background of normal thyroid parenchyma. Finally, because ultrasound is commonly used for surveillance of patients with thyroid carcinoma after thyroidectomy, sonographers should be familiar with the ultrasound appearance of disease recurrence and its mimics.

    View details for DOI 10.1053/j.sult.2012.11.001

    View details for PubMedID 23768889

  • Physiologic, histologic, and imaging features of retained products of conception. Radiographics Sellmyer, M. A., Desser, T. S., Maturen, K. E., Jeffrey, R. B., Kamaya, A. 2013; 33 (3): 781-796


    Retained products of conception (RPOC) are a common and treatable complication after delivery or termination of pregnancy. The pathologic diagnosis of RPOC is made based on the presence of chorionic villi, which indicates persistent placental or trophoblastic tissue. In the setting of postpartum hemorrhage, however, distinguishing RPOC from bleeding related to normal postpartum lochia or uterine atony can be clinically challenging. Ultrasonographic (US) evaluation can be particularly helpful in these patients, and a thickened endometrial echo complex (EEC) or a discrete mass in the uterine cavity is a helpful gray-scale US finding that suggests RPOC. However, gray-scale US findings alone are inadequate for accurate diagnosis. Detection of vascularity in a thickened EEC or an endometrial mass at color or power Doppler US increases the positive predictive value for the diagnosis of RPOC. Computed tomography or magnetic resonance imaging may be helpful when US findings are equivocal and typically demonstrates an enhancing intracavitary mass in patients with RPOC. Diagnostic pitfalls are rare but may include highly vascular RPOC, which can be mistaken for a uterine arteriovenous malformation; true arteriovenous malformations of the uterus; invasive moles; blood clot; and subinvolution of the placental implantation site. © RSNA, 2013.

    View details for DOI 10.1148/rg.333125177

    View details for PubMedID 23674774

  • Aortoenteric fistulas: spectrum of CT findings ABDOMINAL IMAGING Raman, S. P., Kamaya, A., Federle, M., Fishman, E. K. 2013; 38 (2): 367-375


    This article reviews the causes of aortoenteric fistulas, diagnostic options, and important CT findings.Aortoenteric fistula, a rare but potentially fatal entity, presents a significant challenge to radiologists in diagnosis, largely because of its subtle and nonspecific imaging findings. These fistulas can be divided into primary and secondary forms, depending on the presence or absence of prior aortic reconstructive surgery, but the secondary form is more common. Typical CT findings, which can overlap with those seen in perigraft infection, aortitis, infected/mycotic aneurysms, perianeurysmal fibrosis, and the immediate post-operative period after placement of a graft, include: Effacement of the fat planes around the aorta, perigraft fluid/soft tissue thickening, ectopic gas, tethering of adjacent thickened bowel loops towards the aortic graft, and in rare cases, extravasation of contrast from the aorta into the involved segment of bowel.

    View details for DOI 10.1007/s00261-012-9873-7

    View details for Web of Science ID 000316144100019

    View details for PubMedID 22366854

  • Quantitatively Defining Washout in Hepatocellular Carcinoma AMERICAN JOURNAL OF ROENTGENOLOGY Liu, Y. I., Shin, L. K., Jeffrey, R. B., Kamaya, A. 2013; 200 (1): 84-89


    Washout on delayed phase (or equilibrium phase) imaging of an arterially hyperenhancing lesion is an excellent predictor of hepatocellular carcinoma (HCC). The purpose of our study was to quantitatively define washout in pathologically proven HCC. A quantitative definition of HCC may minimize interobserver variability and facilitate more accurate diagnosis.We identified 47 liver lesions that were hyperenhancing in the arterial phase from 24 patients who underwent triphasic MDCT as part of preoperative evaluation for liver transplantation. All HCCs were pathologically proven. Regions of interest were obtained of lesions and areas of adjacent liver on arterial, portal venous, and delayed phase images. Enhancement profiles were assessed by three radiologists.Of the 47 hypervascular lesions, 14 HCCs were identified. There was a statistically significant difference in percentage attenuation ratio (defined as 100 × ratio of attenuation of adjacent liver to that of the lesion) between lesions that were HCC (median percentage attenuation ratio, 121) and those that were not (median percentage attenuation ratio, 101) on delayed phase. Percentage attenuation ratio ? 107 on delayed phase imaging achieved maximal sensitivity (100%) with good specificity (75.8%), positive predictive value (PPV) (63.6%), and negative predictive value (NPV) (100%) in HCC detection. Percentage attenuation ratio also correlated well with radiologists' assessments of enhancement profiles of lesions (multinomial logistic regression McFadden R(2), 0.72; chi-square p, < 0.01).Our analysis of simple CT attenuation measurements indicates that percentage attenuation ratio offers excellent sensitivity, specificity, PPV, and NPV for HCC detection and very good correlation with radiologists' assessments of washout.

    View details for DOI 10.2214/AJR.11.7171

    View details for PubMedID 23255745

  • Positron Emission Tomography for Predicting Pathologic Response After Neoadjuvant Chemoradiotherapy for Locally Advanced Rectal Cancer 50th Annual Meeting of the American-Society-for-Therapeutic-Radiation-Oncology (ASTRO) Chennupati, S. K., Quon, A., Kamaya, A., Pai, R. K., La, T., Krakow, T. E., Graves, E., Koong, A. C., Chang, D. T. LIPPINCOTT WILLIAMS & WILKINS. 2012: 334?39


    To investigate whether before and after chemoradiotherapy (CRT) positron emission tomography (PET) predict for pathologic response after preoperative CRT in patients with locally advanced rectal adenocarcinoma.Thirty-five patients who underwent pre-CRT and post-CRT PET scans before surgery were included. All patients were staged with endoscopic ultrasound or high resolution CT. CRT was given with 50.4 Gy at 1.8 Gy per fraction and concurrent 5-fluorouracil-based chemotherapy. Surgery occurred at a median of 46 days (range, 27 to 112 d) after completing CRT. The maximum standardized uptake value (SUV(max)) and the metabolic tumor volume (MTV) using various minimum SUV thresholds (2, 2.5, 3) on the PET scans (MTV(2.0), MTV(2.5), MTV(3.0)) were determined. Post-CRT PET scans were done 3 to 5 weeks after completion of CRT. Pathologic response was assessed using the tumor regression grade (TRG) scale. Patients with complete or near-complete response (TRG=0 to 1) were considered pathologic responders. The pre-CRT and post-CRT PET scan SUV(max) and MTV values were correlated with TRG. The ?SUV(max) and ?MTV were correlated with TRG.No correlation was seen with SUV(max) (P=0.99), MTV(2.0) (P=0.73), MTV(2.5) (P=0.73), or MTV(3.0) (P=0.31) on the pre-CRT PET between pathologic responders versus nonresponders. No correlation was noted between SUV(max) (P=0.49), MTV(2.0) (P=0.73), MTV(2.5) (P=0.49), or MTV(3.0) (P=0.31) on the post-CRT PET scan and pathologic response. Finally, the ?SUV(max) (P=0.32), ?MTV(2.0) (P=0.99), ?MTV(2.5) (P=0.31), ?MTV(3.0) (P=0.31) did not correlate with pathologic response.Changes seen on PET have limited value in predicting for pathologic response of rectal cancer after preoperative neoadjuvant therapy.

    View details for DOI 10.1097/COC.0b013e3182118d12

    View details for PubMedID 21422989

  • Multidetector Computed Tomography Triphasic Evaluation of the Liver Before Transplantation: Importance of Equilibrium Phase Washout and Morphology for Characterizing Hypervascular Lesions JOURNAL OF COMPUTER ASSISTED TOMOGRAPHY Liu, Y. I., Kamaya, A., Jeffrey, R. B., Shin, L. K. 2012; 36 (2): 213-219


    We aim to identify the sensitivity and positive predictive value (PPV) of arterial phase imaging in detecting hepatocellular carcinoma (HCC) and determine the added value of portal venous and equilibrium phase imaging and lesion morphology characterization.We reviewed all patients who underwent liver transplantation at our institution that had a triphasic multidetector computed tomography examination within 6 months of transplantation. Forty-seven hypervascular lesions were identified in 24 patients. Imaging findings were correlated with explant pathologic correlation.Hypervascularity in the arterial phase resulted in sensitivity of 87.5% and PPV of 29.8%. The presence of washout in the equilibrium phase increased the PPV to 92.9% with a slight decrease in sensitivity (81.3%). The negative predictive value of hypervascular lesions without washout in the equilibrium phase was 97.1%. There was significant correlation between larger lesions and HCC and between round lesions and HCC.The presence of washout in the equilibrium phase is a better indicator of malignancy.

    View details for DOI 10.1097/RCT.0b013e318247c8f0

    View details for PubMedID 22446362

  • Photoacoustic Imaging Using a 9F MicroLinear CMUT ICE Catheter IEEE International Ultrasonics Symposium (IUS) Nikoozadeh, A., Choe, J. W., Kothapalli, S., Moini, A., Sanjani, S. S., Kamaya, A., Oralkan, O., Gambhir, S. S., Khuri-Yakub, P. T. IEEE. 2012: 24?27
  • Ultrasound Imaging of Bowel Pathology: Technique and Keys to Diagnosis in the Acute Abdomen AMERICAN JOURNAL OF ROENTGENOLOGY Maturen, K. E., Wasnik, A. P., Kamaya, A., Dillman, J. R., Kaza, R. K., Pandya, A., Maheshwary, R. K. 2011; 197 (6): W1067-W1075


    This article illustrates the normal and pathologic sonographic appearances of bowel, with an emphasis on diagnostic ultrasound techniques.The current role of ultrasound for adult bowel evaluation is limited in the United States, with CT emerging as the primary modality for evaluation of the acute abdomen. However, mounting concerns regarding diagnostic radiation and health care costs may affect practice patterns and shift utilization back toward sonography, which is widely available and relatively inexpensive.

    View details for DOI 10.2214/AJR.11.6594

    View details for Web of Science ID 000297369900014

    View details for PubMedID 22109321

  • Imaging Manifestations of Abdominal Fat Necrosis and Its Mimics RADIOGRAPHICS Kamaya, A., Federle, M. P., Desser, T. S. 2011; 31 (7): 2021-2034


    Intraabdominal fat is a metabolically active tissue that may undergo necrosis through a number of mechanisms. Fat necrosis is a common finding at abdominal cross-sectional imaging, and it may cause abdominal pain, mimic findings of acute abdomen, or be asymptomatic and accompany other pathophysiologic processes. Common processes that are present in fat necrosis include torsion of an epiploic appendage, infarction of the greater omentum, and fat necrosis related to trauma or pancreatitis. In addition, other pathologic processes that involve fat may be visualized at computed tomography, including focal lipohypertrophy, pathologic fat paucity (lipodystrophies), and malignancies such as liposarcoma, which may mimic benign causes of fat stranding. Because fat necrosis and malignant processes such as liposarcoma and peritoneal carcinomatosis may mimic one another, knowledge of a patient's clinical history and prior imaging studies is essential for accurate diagnosis.

    View details for DOI 10.1148/rg.317115046

    View details for PubMedID 22084185

  • A Bayesian Network for Differentiating Benign From Malignant Thyroid Nodules Using Sonographic and Demographic Features AMERICAN JOURNAL OF ROENTGENOLOGY Liu, Y. I., Kamaya, A., Desser, T. S., Rubin, D. L. 2011; 196 (5): W598-W605


    The objective of our study was to create a Bayesian network (BN) that incorporates a multitude of imaging features and patient demographic characteristics to guide radiologists in assessing the likelihood of malignancy in suspicious-appearing thyroid nodules.We built a BN to combine multiple indicators of the malignant potential of thyroid nodules including both imaging and demographic factors. The imaging features and conditional probabilities relating those features to diagnoses were compiled from an extensive literature review. To evaluate our network, we randomly selected 54 benign and 45 malignant nodules from 93 adult patients who underwent ultrasound-guided biopsy. The final diagnosis in each case was pathologically established. We compared the performance of our network with that of two radiologists who independently evaluated each case on a 5-point scale of suspicion for malignancy. Probability estimates of malignancy from the BN and radiologists were compared using receiver operating characteristic (ROC) analysis.The network performed comparably to the two expert radiologists. Using each radiologist's assessment of the imaging features as input to the network, the differences between the area under the ROC curve (A(z)) for the BN and for the radiologists were -0.03 (BN vs radiologist 1, 0.85 vs 0.88) and -0.01 (BN vs radiologist 2, 0.76 vs 0.77).We created a BN that incorporates a range of sonographic and demographic features and provides a probability about whether a thyroid nodule is benign or malignant. The BN distinguished between benign and malignant thyroid nodules as well as the expert radiologists did.

    View details for DOI 10.2214/AJR.09.4037

    View details for PubMedID 21512051

  • Hepatic Epithelioid Hemangioendothelioma DIGESTIVE DISEASES AND SCIENCES Liu, Y. I., Brown, S. S., Elihu, A., Bonham, C. A., Concepcion, W., Longacre, T. A., Kamaya, A. 2011; 56 (2): 303-306

    View details for DOI 10.1007/s10620-010-1470-4

    View details for PubMedID 21053076

  • Recurrence in the Thyroidectomy Bed: Sonographic Findings AMERICAN JOURNAL OF ROENTGENOLOGY Kamaya, A., Gross, M., Akatsu, H., Jeffrey, R. B. 2011; 196 (1): 66-70


    The purpose of this article is to characterize sonographic features of differentiated thyroid cancer recurrence in the thyroidectomy bed.Patients referred for biopsy of thyroidectomy bed lesions between February 2006 and December 2009 were identified. Patient data and gray-scale and color Doppler features were recorded.Results of ultrasound-guided biopsies of 30 nodules in 27 patients were reviewed. Twenty-five lesions yielded diagnostic findings, including 22 recurrences in 19 patients and three benign lesions in three patients. Five biopsies were nondiagnostic. Among the 22 recurrences, 21 (95%) were hypoechoic and one (5%) was mixed hypoechoic and hyperechoic on gray-scale imaging. On Doppler imaging, 100% of recurrences had detectable vascularity. Eight lesions (36%) had microcalcifications, and five (23%) had coarse calcifications; the average long-axis dimension was 1.5 cm. Of the five nondiagnostic lesions, four (80%) were hypoechoic, one (20%) was isoechoic, one (20%) had microcalcifications, none had coarse calcifications, and two (40%) had vascularity; the average long-axis dimension was 0.6 cm. Of the negative lesions, three (100%) were hypoechoic, two (66%) had vascularity, and two (66%) had coarse calcifications. No microcalcifications were seen, and the average long-axis dimension was 2 cm. Serum thyroglobulin (Tg) or anti-Tg antibodies were elevated in 12 (63%) of 19 patients with recurrence (eight [42%] with elevated Tg levels and four [21%] with elevated anti-Tg antibody levels).An ultrasound finding of a hypoechoic thyroidectomy bed lesion with internal vascularity and size greater than 6 mm is highly sensitive in predicting recurrence. Serum Tg levels were less sensitive than ultrasound in detection of recurrence in the thyroidectomy bed.

    View details for DOI 10.2214/AJR.10.4474

    View details for Web of Science ID 000286018800009

    View details for PubMedID 21178048

  • Informatics in Radiology RADTF: A Semantic Search-enabled, Natural Language Processor-generated Radiology Teaching File RADIOGRAPHICS Do, B. H., Wu, A., Biswal, S., Kamaya, A., Rubin, D. L. 2010; 30 (7): 2039-2048


    Storing and retrieving radiology cases is an important activity for education and clinical research, but this process can be time-consuming. In the process of structuring reports and images into organized teaching files, incidental pathologic conditions not pertinent to the primary teaching point can be omitted, as when a user saves images of an aortic dissection case but disregards the incidental osteoid osteoma. An alternate strategy for identifying teaching cases is text search of reports in radiology information systems (RIS), but retrieved reports are unstructured, teaching-related content is not highlighted, and patient identifying information is not removed. Furthermore, searching unstructured reports requires sophisticated retrieval methods to achieve useful results. An open-source, RadLex(®)-compatible teaching file solution called RADTF, which uses natural language processing (NLP) methods to process radiology reports, was developed to create a searchable teaching resource from the RIS and the picture archiving and communication system (PACS). The NLP system extracts and de-identifies teaching-relevant statements from full reports to generate a stand-alone database, thus converting existing RIS archives into an on-demand source of teaching material. Using RADTF, the authors generated a semantic search-enabled, Web-based radiology archive containing over 700,000 cases with millions of images. RADTF combines a compact representation of the teaching-relevant content in radiology reports and a versatile search engine with the scale of the entire RIS-PACS collection of case material.

    View details for DOI 10.1148/rg.307105083

    View details for Web of Science ID 000284094200021

    View details for PubMedID 20801868

  • 3-D Deep Penetration Photoacoustic Imaging with a 2-D CMUT Array. Proceedings. IEEE Ultrasonics Symposium Ma, T., Kothapalli, S. R., Vaithilingam, S., Oralkan, O., Kamaya, A., Wygant, I. O., Zhuang, X., Gambhir, S. S., Jeffrey, R. B., Khuri-Yakub, B. T. 2010; 2010: 375-377


    In this work, we demonstrate 3-D photoacoustic imaging of optically absorbing targets embedded as deep as 5 cm inside a highly scattering background medium using a 2-D capacitive micromachined ultrasonic transducer (CMUT) array with a center frequency of 5.5 MHz. 3-D volumetric images and 2-D maximum intensity projection images are presented to show the objects imaged at different depths. Due to the close proximity of the CMUT to the integrated frontend circuits, the CMUT array imaging system has a low noise floor. This makes the CMUT a promising technology for deep tissue photoacoustic imaging.

    View details for PubMedID 22977296

  • Pathological response after chemoradiation for T3 rectal cancer COLORECTAL DISEASE Chennupati, S. K., Kamaya, A., Fisher, G. A., Ford, J. M., Kunz, P., Itakura, H., Welton, M. L., Shelton, A., Van Dam, J., Koong, A. C., Chang, D. T. 2010; 12 (7): E24-E30


    The aim of this study was to investigate the effect of preoperative chemoradiotherapy (CRT) on nodal disease in locally advanced rectal adenocarcinoma.Thirty-two patients staged uT3N0 and 27 patients staged uT3N1 rectal adenocarcinoma who underwent pre-CRT staging using endoscopic ultrasound or rectal protocol CT were included. The median radiation dose was 50.4 Gy (range: 45-50.4 Gy) at 1.8 Gy per fraction and all patients received concurrent 5-FU or capecitabine-based chemotherapy. Low anterior resection or abdomino-perineal resection occurred at a median of 46 days (range: 27-112 days) after CRT.Eleven of 32 uT3N0 patients (34.4%) and 13 of 26 uT3N1 patients (50.0%) had ypN+ (P = 0.29). For patients with uT3N0, 10 of 20 (50.0%) with ypT2-3 and 1 of 12 (8.3%) with ypT0-1 were ypN+ (P = 0.02). For patients with uT3N1, 12 of 20 (60.0%) with ypT2-3 and 1 of 6 (16.7%) with ypT0-1 were ypN+ (P = 0.16). Overall, the ypN+ rate was 11.1% in the ypT0-yT1 group compared with 55.0% in the ypT2-yT3 group (P = 003). Among patients with uT3N0 disease, the ypN+ rate in patients who had surgery > 46 days vs 46 days vs 46 days vs

    View details for DOI 10.1111/j.1463-1318.2009.02013.x

    View details for Web of Science ID 000208355900003

  • Interpatient Variability of Enhancement of Five Abdominal Organs in Triphasic MDCT 110th Annual Meeting of the American-Roentgen-Ray-Society Liu, Y., Shin, L., Jeffrey, R., Kamaya, A. AMER ROENTGEN RAY SOC. 2010
  • A Systemic Search for Patterns for Thyroid Nodule Evaluation Using a Bayesian Classifier 110th Annual Meeting of the American-Roentgen-Ray-Society Liu, Y., Kamaya, A., Desser, T., Rubin, D. AMER ROENTGEN RAY SOC. 2010
  • Learning a Bayesian Classifier for Thyroid Nodule Evaluation 110th Annual Meeting of the American-Roentgen-Ray-Society Liu, Y., Kamaya, A., Desser, T., Rubin, D. AMER ROENTGEN RAY SOC. 2010
  • What Defines Hepatic "Washout" in Triphasic MDCT? 110th Annual Meeting of the American-Roentgen-Ray-Society Liu, Y., Shin, I., Jeffrey, R., Kamaya, A. AMER ROENTGEN RAY SOC. 2010
  • Three-Dimensional Photoacoustic Imaging Using a Two-Dimensional CMUT Array IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Vaithilingam, S., Ma, T., Furukawa, Y., Wygant, I. O., Zhuang, X., de la Zerda, A., Oralkan, O., Kamaya, A., Gambhir, S. S., Jeffrey, R. B., Khuri-Yakub, B. T. 2009; 56 (11): 2411-2419


    In this paper, we describe using a 2-D array of capacitive micromachined ultrasonic transducers (CMUTs) to perform 3-D photoacoustic and acoustic imaging. A tunable optical parametric oscillator laser system that generates nanosecond laser pulses was used to induce the photoacoustic signals. To demonstrate the feasibility of the system, 2 different phantoms were imaged. The first phantom consisted of alternating black and transparent fishing lines of 180 mum and 150 mum diameter, respectively. The second phantom comprised polyethylene tubes, embedded in chicken breast tissue, filled with liquids such as the dye indocyanine green, pig blood, and a mixture of the 2. The tubes were embedded at a depth of 0.8 cm inside the tissue and were at an overall distance of 1.8 cm from the CMUT array. Two-dimensional cross-sectional slices and 3-D volume rendered images of pulse-echo data as well as photoacoustic data are presented. The profile and beamwidths of the fishing line are analyzed and compared with a numerical simulation carried out using the Field II ultrasound simulation software. We investigated using a large aperture (64 x 64 element array) to perform photoacoustic and acoustic imaging by mechanically scanning a smaller CMUT array (16 x 16 elements). Two-dimensional transducer arrays overcome many of the limitations of a mechanically scanned system and enable volumetric imaging. Advantages of CMUT technology for photoacoustic imaging include the ease of integration with electronics, ability to fabricate large, fully populated 2-D arrays with arbitrary geometries, wide-bandwidth arrays and high-frequency arrays. A CMUT based photoacoustic system is proposed as a viable alternative to a piezoelectric transducer based photoacoustic systems.

    View details for DOI 10.1109/TUFFC.2009.1329

    View details for Web of Science ID 000271478600010

    View details for PubMedID 19942528

  • Hypervascular Liver Lesions SEMINARS IN ULTRASOUND CT AND MRI Kamaya, A., Maturen, K. E., Tye, G. A., Liu, Y. I., Parti, N. N., Desser, T. S. 2009; 30 (5): 387-407


    Hypervascular hepatocellular lesions include both benign and malignant etiologies. In the benign category, focal nodular hyperplasia and adenoma are typically hypervascular. In addition, some regenerative nodules in cirrhosis may be hypervascular. Malignant hypervascular primary hepatocellular lesions include hepatocellular carcinoma, fibrolamellar carcinoma, and peripheral cholangiocarcinoma. Vascular liver lesions often appear hypervascular because they tend to follow the enhancement of the blood pool; these include hemangiomas, arteriovenous malformations, angiosarcomas, and peliosis. While most gastrointestinal malignancies that metastasize to the liver will appear hypovascular on arterial and portal-venous phase imaging, certain cancers such as metastatic neuroendocrine tumors (including pancreatic neuroendocrine tumors, carcinoid, and gastrointestinal stromal tumors) tend to produce hypervascular metastases due to the greater recruitment of arterial blood supply. Finally, rare hepatic lesions such as glomus tumor and inflammatory pseudotumor may have a hypervascular appearance.

    View details for DOI 10.1053/j.sult.2009.06.001

    View details for PubMedID 19842564

  • Imaging and Diagnosis of Postpartum Complications Sonography and Other Imaging Modalities ULTRASOUND QUARTERLY Kamaya, A., Ro, K., Benedetti, N. J., Chang, P. L., Desser, T. S. 2009; 25 (3): 151-162


    Postpartum complications can be broadly divided into 4 categories: postpartum hemorrhage, obstetrical trauma, thromboembolic complications, and puerperal infections. Postpartum hemorrhage is most commonly caused by uterine atony, abnormal placentation, or genital tract trauma. Secondary causes of hemorrhage include retained products of conception and, rarely, subinvolution of the placental implantation site. Uterine dehiscence or rupture may be occult on ultrasound examination and may be better visualized on sagittal computed tomography or magnetic resonance imaging. Obstetric trauma during prolonged vaginal or cesarean delivery may lead to fistula formation, ureteral injury, or bowel injury. Later potential complications of cesarean delivery include cesarean delivery scar ectopic, endometrial implants in the cesarean scar, and placenta accreta. Thromboembolic complications can include pulmonary embolism and deep vein thrombosis as well as ovarian vein thrombosis, the latter of which can be difficult to clinically differentiate from appendicitis in the postpartum female.

    View details for PubMedID 19730078

  • Retained Products of Conception Spectrum of Color Doppler Findings JOURNAL OF ULTRASOUND IN MEDICINE Kamaya, A., Petrovitch, I., Chen, B., Frederick, C. E., Jeffrey, R. B. 2009; 28 (8): 1031-1041


    The purpose of this study was to characterize color Doppler imaging features of retained products of conception (RPOC) with gray scale correlation.Clinically suspected cases of RPOC between January 2005 and February 2008 were reviewed. Patient data and relevant color Doppler and gray scale features were recorded.A total of 269 patients referred for sonographic evaluation for RPOC were identified. Thirty-five patients had confirmed pathologic diagnoses, 28 of whom had RPOC. In those with RPOC, 5 (18%) were avascular (type 0); 6 (21%) had minimal vascularity (type 1); 12 (43%) had moderate vascularity (type 2); and 5 (18%) had marked vascularity (type 3). Peak systolic velocities ranged from 10 to 108 cm/s (average, 36.1 cm/s). Resistive indices in arterial waveforms ranged from 0.33 to 0.7 (average, 0.5). Five (45%) of the patients with type 0 vascularity had RPOC; 6 (86%) of those with type 1 had RPOC; and 17 (100%) of those with types 2 and 3 had RPOC. An echogenic mass had a moderate positive predictive value (80%) but low sensitivity (29%) for RPOC.Color Doppler evaluation of the endometrium is helpful in determining the presence of RPOC. Endometrial vascularity is highly correlated with RPOC, whereas the lack of vascularity can be seen in both intrauterine clots and avascular RPOC.

    View details for Web of Science ID 000268556800008

    View details for PubMedID 19643786

  • Laparoscopic radical nephrectomy after shrinkage of a caval tumor thrombus with sunitinib NATURE REVIEWS UROLOGY Harshman, L. C., Srinivas, S., Kamaya, A., Chung, B. I. 2009; 6 (6): 338-343


    A 57-year-old woman presented to the emergency department at a community hospital with a 2-month history of fatigue and right-sided flank and abdominal pain. Noncontrast CT of the abdomen and pelvis revealed a 9.1 cm right renal mass.Contrast CT of the chest, abdomen and pelvis, MRI of the abdomen and pelvis with gadolinium, radionuclide bone scan, lung nodule biopsy, complete blood count, comprehensive metabolic profile, and measurement of serum lactate dehydrogenase.Stage IV, T3bN0M1 clear cell renal cell carcinoma, with an associated tumor thrombus extending into the vena cava.The patient was treated with neoadjuvant sunitinib, which resulted in a marked response in the primary tumor and metastatic lesions as well as regression of the tumor thrombus well into the renal vein. Thus, laparoscopic radical nephrectomy was feasible and was achieved without hemorrhagic or wound healing complications. One month after surgery, she had evidence of disease progression in the lung and a periaortic lymph node. She was restarted on sunitinib with resultant disease stabilization, but discontinued the drug owing to toxicity. Eight months after cessation of sunitinib, she received a dendritic cell vaccine. She remains alive without evidence of disease progression 2 years after her diagnosis.

    View details for DOI 10.1038/nrurol.2009.84

    View details for PubMedID 19498412

  • A Controlled Vocabulary to Represent Sonographic Features of the Thyroid and its Application in a Bayesian Network to Predict Thyroid Nodule Malignancy 109th Annual Meeting of the American-Roentgen-Ray-Society Liu, Y., Kamaya, A., Desser, T., Rubin, D. AMER ROENTGEN RAY SOC. 2009
  • Differentiating a Benign From Malignant Liver Lesion in the Pretransplant Cirrhotic Liver on Triphasic MDCT: When to Worry, When to Relax? 109th Annual Meeting of the American-Roentgen-Ray-Society Liu, Y., Shin, L., Kamaya, A., Jeffrey, R. AMER ROENTGEN RAY SOC. 2009
  • Intraoperative Ultrasound of the Pancreas ULTRASOUND QUARTERLY Shin, L. K., Brant-Zawadzki, G., Kamaya, A., Jeffrey, R. B. 2009; 25 (1): 39-48


    Intraoperative ultrasound provides spatial resolution of the pancreas superior to computed tomography, magnetic resonance imaging, and transabdominal sonography. This pictorial essay will review common benign and malignant pancreatic processes including the following: pancreatic ductal adenocarcinoma, pancreatitis, endocrine tumors, mucinous cystic neoplasm, intraductal papillary mucinous neoplasm, serous cystadenoma, and solid pseudopapillary tumor. The use of intraoperative ultrasound in specific surgical situations will be discussed, which include the following: (1) identification of insulinoma(s) which are not detectable preoperatively, (2) identification of the pancreatic duct to determine dissection planes for chronic pancreatitis surgery (eg, Puestow procedure) and for tumor resection, and (3) staging purposes for malignant disease.

    View details for Web of Science ID 000208118300005

    View details for PubMedID 19276960

  • Optimal Vascular and Parenchymal Contrast Enhancement: The Current State of the Art RADIOLOGIC CLINICS OF NORTH AMERICA Fleischmann, D., Kamaya, A. 2009; 47 (1): 13-?


    A fundamental understanding of early arterial and parenchymal contrast medium (CM) dynamics is the basis for the design of CT scanning and injection protocols for state-of-the-art cardiovascular and body CT applications. Although normal parenchymal enhancement is primarily controlled by the total iodine dose injected per body weight, arterial enhancement is controlled by the iodine flux, the injection duration, and cardiac output. The technical capabilities of modern CT equipment allow and require precise scan timing to synchronize data acquisition with the desired phase of vascular enhancement (for CTA) and parenchymal enhancement (for liver and pancreatic CT). Automated tube current modulation and weight-based injection protocols allow individual optimization of radiation exposure and reduce interindividual variability of CM enhancement.

    View details for DOI 10.1016/j.rcl.2008.10.009

    View details for Web of Science ID 000263843900003

    View details for PubMedID 19195531

  • A Controlled Vocabulary to Represent Sonographic Features of the Thyroid and its application in a Bayesian Network to Predict Thyroid Nodule Malignancy. Summit on translational bioinformatics Liu, Y. I., Kamaya, A., Desser, T. S., Rubin, D. L. 2009; 2009: 68-72


    It is challenging to distinguish benign from malignant thyroid nodules on high resolution ultrasound. Many ultrasound features have been studied individually as predictors for thyroid malignancy, none with a high degree of accuracy, and there is no consistent vocabulary used to describe the features. Our hypothesis is that a standard vocabulary will advance accuracy. We performed a systemic literature review and identified all the sonographic features that have been well studied in thyroid cancers. We built a controlled vocabulary for describing sonographic features and to enable us to unify data in the literature on the predictive power of each feature. We used this terminology to build a Bayesian network to predict thyroid malignancy. Our Bayesian network performed similar to or slightly better than experienced radiologists. Controlled terminology for describing thyroid radiology findings could be useful to characterize thyroid nodules and could enable decision support applications.

    View details for PubMedID 21347173

  • Emergency Gynecologic Imaging SEMINARS IN ULTRASOUND CT AND MRI Kamaya, A., Shin, L., Chen, B., Desser, T. S. 2008; 29 (5): 353-368


    Acute pelvic pain in the female patient can have myriad presentations and, depending on the diagnosis, profound consequences. In the pregnant patient with pelvic pain or bleeding, an ectopic pregnancy must be first excluded. Ultrasound is important in determining the size and location of the ectopic pregnancy, and presence of bleeding, which in turn helps guide treatment decisions. Subchorionic or subplacental bleeds in an intrauterine pregnancy may also present with vaginal bleeding with consequences dependent on gestational age and size of bleed. In the postpartum female suspected to have retained products of conception, sonographic findings may vary from a thickened endometrial stripe to an echogenic mass with associated marked vascularity, often mimicking an arterial-venous malformation. In the nonpregnant patient, early diagnosis and treatment of ovarian torsion can preserve ovarian function. Other causes of peritoneal irritation may also cause acute pelvic pain including a ruptured hemorrhagic cyst or ruptured endometrioma. When pelvic inflammatory disease is suspected, imaging is used to evaluate for serious associated complications including the presence of a tuboovarian abscess or peritonitis. While leiomyomas of the uterus are largely asymptomatic, a leiomyoma that undergoes necrosis, torsion or prolapse through the cervix may be associated with acute severe pain or bleeding. The imaging features of these and other important clinical entities in the female pelvis will be presented.

    View details for DOI 10.1053/j.sult.2008.06.006

    View details for PubMedID 18853841

  • Fetus in fetu: 11 fetoid forms in a single fetus - Review of the literature and imaging JOURNAL OF ULTRASOUND IN MEDICINE Gerber, R. E., Kamaya, A., Miller, S. S., Cronin, D. M., Dwyer, B., Chueh, J., Conner, K. E., Barth, R. A. 2008; 27 (9): 1381-1387

    View details for Web of Science ID 000258853200015

    View details for PubMedID 18716149

  • Ultrasound of thyroid nodules NEUROIMAGING CLINICS OF NORTH AMERICA Desser, T. S., Kamaya, A. 2008; 18 (3): 463-478


    Thyroid nodules can be detected in 4% to 8% of the adult population by palpation, but in 40% to 50% of the population by ultrasound. The overwhelming majority of these represent benign hyperplastic nodules or adenomas. Approximately 5% of nodules are malignant, with papillary carcinoma representing approximately 75% to 80% of primary thyroid malignancies. Although many sonographic features have been studied as a means of distinguishing benign from malignant nodules, ultrasound-guided fine-needle aspiration with cytologic evaluation remains a mainstay in the management of palpable and incidentally detected nodules. This article reviews the current techniques for sonographic evaluation of the thyroid and the imaging features of the various types of thyroid nodules.

    View details for DOI 10.1016/j.nic.2008.03.005

    View details for PubMedID 18656028

  • An unusual imaging and clinical presentation of papillary thyroid carcinoma JOURNAL OF ULTRASOUND IN MEDICINE Liu, Y. I., Shin, L. K., Kamaya, A., Jeffrey, R. B. 2008; 27 (8): 1241-1244

    View details for PubMedID 18645084

  • Initial evaluation of F-18-fluorothymidine (FLT) PET/CT scanning for primary pancreatic cancer EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING Quon, A., Chang, S. T., Chin, F., Kamaya, A., Dick, D. W., Loo, B. W., Gambhir, S. S., Koong, A. C. 2008; 35 (3): 527-531


    The aim of this study was to evaluate the potential of (18)F-fluorothymidine (FLT) PET/CT for imaging pancreatic adenocarcinoma.This was a pilot study of five patients (four males, one female) with newly diagnosed and previously untreated pancreatic adenocarcinoma. Patients underwent FLT PET/CT, (18)F-fluorodeoxyglucose (FDG) PET/CT, and contrast-enhanced CT scanning before treatment. The presence of cancer was confirmed by histopathological analysis at the time of scanning in all five patients. The degree of FLT and FDG uptake at the primary tumor site was assessed using visual interpretation and semi-quantitative SUV analyses.The primary tumor size ranged from 2.5 x 2.8 cm to 3.5 x 7.0 cm. The SUV of FLT uptake within the primary tumor ranged from 2.1 to 3.1. Using visual interpretation, the primary cancer could be detected from background activity in two of five patients (40%) on FLT PET/CT. By comparison, FDG uptake was higher in each patient with a SUV range of 3.4 to 10.8, and the primary cancer could be detected from background in all five patients (100%).In this pilot study of five patients with primary pancreatic adenocarcinoma, FLT PET/CT scanning showed poor lesion detectability and relatively low levels of radiotracer uptake in the primary tumor.

    View details for DOI 10.1007/s00259-007-0630-z

    View details for Web of Science ID 000254402800010

    View details for PubMedID 17960376

  • A Bayesian classifier for differentiating benign versus malignant thyroid nodules using sonographic features. AMIA ... Annual Symposium proceedings / AMIA Symposium. AMIA Symposium Liu, Y. I., Kamaya, A., Desser, T. S., Rubin, D. L. 2008: 419-423


    Thyroid nodules are a common, yet challenging clinical problem. The vast majority of these nodules are benign; however, deciding which nodule should undergo biopsy is difficult because the imaging appearance of benign and malignant thyroid nodules overlap. High resolution ultrasound is the primary imaging modality for evaluating thyroid nodules. Many sonographic features have been studied individually as predictors for thyroid malignancy. There has been little work to create predictive models that combine multiple predictors, both imaging features and demographic factors. We have created a Bayesian classifier to predict whether a thyroid nodule is benign or malignant using sonographic and demographic findings. Our classifier performed similar to or slightly better than experienced radiologists when evaluated using 41 thyroid nodules with known pathologic diagnosis. This classifier could be helpful in providing practitioners an objective basis for deciding whether to biopsy suspicious thyroid nodules.

    View details for PubMedID 18999209

  • Investigating Large 2D Arrays for Photoacoustic and Acoustic Imaging using CMUT Technology IEEE Ultrasonics Symposium Vaithilingam, S., Ma, T., Furukawa, Y., Oralkan, O., Kamaya, A., Torashima, K., Kupnik, M., Wygant, I. O., Zhuang, X., Jeffrey, R. B., Khuri-Yakub, B. T. IEEE. 2008: 1238?1241
  • A co-axial scanning acoustic and. photoacoustic microscope IEEE Ultrasonics Symposium Vaithilingam, S., Ma, T., Furukawa, Y., de la Zerda, A., Oralkan, O., Kamaya, A., Keren, S., Gambhir, S. S., Jeffrey, R. B., Khuri-Yakub, B. T. IEEE. 2007: 2413?2416
  • Sonography of the abnormal parathyroid gland. Ultrasound quarterly Kamaya, A., Quon, A., Jeffrey, R. B. 2006; 22 (4): 253-262


    In 80% to 90% of patients with primary hyperparathyroidism, a single parathyroid adenoma will be identified as the culprit, whereas the remaining 10% to 20% are caused by multiple adenomas, parathyroid hyperplasia, and rarely, parathyroid carcinoma. At the 2002 National Institute of Health consensus meeting, minimally invasive parathyroidectomy was endorsed as a promising and attractive alternative to total parathyroidectomy. Therefore, preoperative localization of the adenoma is critical in the clinical evaluation of the patient before surgical resection. Although adenomas less than 1 cm may be difficult to visualize sonographically, knowledge of typical imaging characteristics of parathyroid adenomas and use of special sonographic techniques will facilitate identification in most patients. Typical imaging characteristics of parathyroid adenomas include homogeneously hypoechoic echotexture on gray scale with an enlarged feeding artery and peripheral arc of vascularity seen on color and power Doppler. Proper neck extension, unilateral graded compression techniques, and patient swallowing will improve visualization of adenomas.

    View details for PubMedID 17146333

  • Multiple lesions of the spleen: Differential diagnosis of cystic and solid lesions SEMINARS IN ULTRASOUND CT AND MRI Kamaya, A., Weinstein, S., Desser, T. S. 2006; 27 (5): 389-403


    Lesions in the spleen may be encountered in a variety of clinical settings ranging from asymptomatic patients to patients who are critically ill. Etiologies for multifocal splenic lesions include infectious and inflammatory processes, primary vascular and lymphoid neoplasms, metastatic disease, vascular processes, and systemic diseases. There is often overlap in the imaging appearance alone, so the clinical setting is very helpful in differential diagnosis. In the immunocompromised patient, multiple small splenic lesions usually represent disseminated fungal disease and microabscesses. The spleen is a relatively rare site for metastatic disease; patients with metastatic lesions in the spleen usually have disease in other sites as well. Breast, lung, ovary, melanoma, and colon cancer are common primary tumors that metastasize to the spleen. Vascular neoplasms of the spleen represent the majority of the nonhematologic/nonlymphoid neoplasms and commonly produce multifocal lesions. Splenic infarcts may be seen with localized processes such as portal hypertension or pancreatitis, or may arise from an embolic source. Radiologists should be aware of the spectrum of processes that may involve the spleen and the clinical context in which they occur.

    View details for DOI 10.1053/j.sult.2006.06.004

    View details for PubMedID 17048454

  • Multidetector CT imaging thoracoabdominal of aortic aneurysms 105th Annual Meeting of the American-Roentgen-Ray-Society Kamaya, A., Cheung, S., Miller, D. C., Hellinger, J. C., Hallett, R., Fleischmann, D. AMER ROENTGEN RAY SOC. 2005: 134?34
  • Characterization of a linear streak artifact with pulse inversion tissue harmonics in musculoskeletal Sonography 13th Annual Meeting of the Society-of-Radiologists-in-Ultrasound Kamaya, A., Abate, S., Nan, B., Grover, I., Adler, R. S., Jamadar, D., Rubin, J. M. AMER INST ULTRASOUND MEDICINE. 2004: 1597?1605


    To understand a linear artifact that projects deep to reflective structures that move rapidly while using tissue harmonic imaging with pulse inversion (PI) sonography. We hypothesize that this artifact is due to a cancellation error between firings in PI imaging, and it is, therefore, similar in generation to the twinkling artifact in color Doppler sonography. This artifact could be studied with the use of surfaces of different roughness to represent different rates of motion, in which roughness corresponds to spatial fluctuations in surface height. Given very slight variations in beam focusing as occurs with sonographic imaging arrays, these spatial fluctuations translate into temporal fluctuations in the received signal as would occur with tissue motion.We scanned 4 different sandpaper grits and a smooth surface through a water path using fundamental and PI mode, 1- and 2-pulse techniques, respectively. The sandpaper and the smooth surface were scanned through a water path at mechanical indices of 0.1 to 0.7. Four independent images were subtracted pairwise to remove nonfluctuating signals. These noise pixels were counted and analyzed.Analysis of variance showed that the noise generated behind the different surfaces was highly significantly different. Two-tailed t tests generally showed significant differences in the quantity of noise between fundamental and harmonic imaging behind the roughest 3 grades of sandpaper. A multiple regression model showed significantly greater slopes for harmonic imaging for all grades of sandpaper and the smooth surface.The noise and, by extension, the linear streak artifact in musculoskeletal imaging are dependent on the mechanical index and are functions of sandpaper roughness. This would be equivalent to a subtraction error between 2 firings due to soft tissue motion, and the artifact may be a way to identify rapid soft tissue motion in PI images.

    View details for Web of Science ID 000225515300006

    View details for PubMedID 15557302

  • Twinkling artifact on color Doppler sonography: Dependence on machine parameters and underlying cause 102nd Annual Meeting of the American-Roentgen-Ray-Society Kamaya, A., Tuthill, T., Rubin, J. M. AMER ROENTGEN RAY SOC. 2003: 215?22


    The objective of our study was to evaluate the color Doppler sonographic effect known as twinkling artifact.Struvite (ammonium magnesium phosphate) stone fragments, wire mesh, and a flat surface were scanned in a water bath with a sonography scanner using a high-frequency linear array probe fixed in a ring clamp. Pulse repetition frequency, color-write priority, gray-scale gain, and spectral Doppler gain were varied. Color and spectral Doppler modes were used.Twinkling artifact and spectral broadening were seen most intensely behind struvite stone fragments, and both were seen more strongly behind wire mesh with greater surface roughness than behind wire mesh with less surface roughness or a flat surface. The appearance of the twinkling artifact is highly dependent on machine settings. System noise measured on a flat surface generates a band-limited Doppler shift on spectral displays with a mean frequency shift of 0 Hz and a mean (+/- SD) absolute fluctuation of 86 +/- 10 Hz over a pulse repetition frequency range of 1250-10,000 Hz. Rough surfaces increase the spectral bandwidth.The appearance of the twinkling artifact is highly dependent on machine settings and is likely generated by a narrow-band, intrinsic machine noise called phase (or clock) jitter. Surface roughness secondarily broadens the noise spectrum. With a strongly reflecting, rough surface such as a renal stone, the high amplitude, broadband signal appears as random motion in color Doppler sonography. Understanding of the twinkling artifact may result in better use of its clinical appearance.

    View details for Web of Science ID 000179979400040

    View details for PubMedID 12490508

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