Bio

Clinical Focus


  • Emergency Medicine
  • Graduate Medical Education

Education & Certifications


  • Board Certification: Emergency Medicine, American Board of Emergency Medicine (2016)
  • Residency:Thomas Jefferson University Hospitalls (2015) PA
  • Internship:Thomas Jefferson University Hospitals (2013) PA
  • Medical Education:State University of New York at Stony Brook Health Sciences Center (2012) NY

Research & Scholarship

Current Research and Scholarly Interests


Emergency Department transitions of care
Graduate medical education
Quality improvement
Patient safety

Professional

Professional Affiliations and Activities


  • Vice-President, American Academy of Emergency Medicine - Young Physicians Section (2016 - Present)
  • Director-at-Large, American Academy of Emergency Medicine - Young Physicians Section (2015 - 2016)

Publications

All Publications


  • Demographics of carotid atherosclerotic plaque features imaged by computed tomography JOURNAL OF NEURORADIOLOGY Chien, J. D., Furtado, A., Cheng, S., Lam, J., Schaeffer, S., Chun, K., Wintermark, M. 2013; 40 (1): 1-10

    Abstract

    This was a prospective, cross-sectional study to evaluate the risk factors and symptoms associated with specific carotid wall and atherosclerotic plaque features as seen on computed tomography-angiography (CTA) studies.A total of 120 consecutive consenting patients admitted to the emergency department with suspected cerebrovascular ischemia, and receiving standard-of-care CTA of the brain and neck on a 64-slice CT scanner, were prospectively enrolled in the study. The carotid wall features observed on CT were quantitatively analyzed with customized software using different radiodensities for contrast-phase acquisition of the carotids. Clinical datasets, including a complete medical history and examination, were obtained by research physicians or specially trained associates blinded to any findings on CT. Univariate and multivariate analyses were performed to assess the degree of association between clinical indicators and quantitative CT features of carotid atherosclerotic plaques.Men tended to have increased carotid lumen (coefficient: 608.7; 95% CI: 356.9-860.6; P<0.001) and wall volumes (209.2; 54.5-364.0; P=0.008), and hypertension was associated with increased wall volume (260.6; 88.7-432.6; P=0.003). Advanced age was associated with increases in maximum wall thickness (0.02; 0.003-0.05; P=0.029), fibrous cap thickness (0.005; 0.001-0.008; P=0.016) and number of calcium voxels (2.7; 1.25-4.2; P<0.001), and the presence of a carotid bruit was associated with carotid stenosis length (21.0; 5.38-37.8; P=0.009). Exercise was inversely related to the number of calcium (-37.1; -71.5 - -2.7; P=0.035) and lipid (-7.9; -15.1 - -0.7; P=0.032) voxels. ACE inhibitor use was associated with fibrous cap thickness (0.1; 0.04-0.23; P=0.005).Significant associations were found between clinical descriptors and carotid atherosclerotic plaque features as revealed by CT. Future studies are needed to validate our findings, and to continue investigations into whether CT features of carotid plaques can be used as biomarkers to quantify the impact of strategies aiming to correct vascular risk factors.

    View details for DOI 10.1016/j.neurad.2012.05.008

    View details for Web of Science ID 000317092100001

    View details for PubMedID 23428245

  • Carotid Atherosclerosis Does Not Predict Coronary, Vertebral, or Aortic Atherosclerosis in Patients With Acute Stroke Symptoms STROKE Adraktas, D. D., Brasic, N., Furtado, A. D., Cheng, S., Ordovas, K., Chun, K., Chien, J. D., Schaeffer, S., Wintermark, M. 2010; 41 (8): 1604-1609

    Abstract

    The purpose of this study was to determine whether significant atherosclerotic disease in the carotid arteries predicts significant atherosclerotic disease in the coronary arteries, vertebral arteries, or aorta in patients with symptoms of acute ischemic stroke.Atherosclerotic disease was imaged using CT angiography in a prospective study of 120 consecutive patients undergoing emergent CT evaluation for symptoms of stroke. Using a comprehensive CT angiography protocol that captured the carotid arteries, coronary arteries, vertebral arteries, and aorta, we evaluated these arteries for the presence and severity of atherosclerotic disease. Significant atherosclerotic disease was defined as >50% stenosis in the carotid, coronary, and vertebral arteries, or >or=4 mm thickness and encroaching in the aorta. Presence of any and significant atherosclerotic disease was compared in the different types of arteries assessed.Of these 120 patients, 79 had CT angiography examinations of adequate image quality and were evaluated in this study. Of these 79 patients, 33 had significant atherosclerotic disease. In 26 of these 33 patients (79%), significant disease was isolated to 1 type of artery, most often to the coronary arteries (N=14; 54%). Nonsignificant atherosclerotic disease was more systemic and involved multiple arteries.Significant atherosclerotic disease in the carotid arteries does not predict significant atherosclerotic disease in the coronary arteries, vertebral arteries, or aorta in patients with symptoms of acute ischemic stroke. Significant atherosclerotic disease is most often isolated to 1 type of artery in these patients, whereas nonsignificant atherosclerotic disease tends to be more systemic.

    View details for DOI 10.1161/STROKEAHA.109.577437

    View details for Web of Science ID 000280330700005

    View details for PubMedID 20595672

  • The Triple Rule-Out for Acute Ischemic Stroke: Imaging the Brain, Carotid Arteries, Aorta, and Heart AMERICAN JOURNAL OF NEURORADIOLOGY Furtado, A. D., Adraktas, D. D., Brasic, N., Cheng, S., Ordovas, K., Smith, W. S., Lewin, M. R., Chun, K., Chien, J. D., Schaeffer, S., Wintermark, M. 2010; 31 (7): 1290-1296

    Abstract

    Ischemic stroke is commonly embolic, either from carotid atherosclerosis or from cardiac origin. These potential sources of emboli need to be investigated to accurately prescribe secondary stroke prevention. Moreover, the mortality in ischemic stroke patients due to ischemic heart disease is greater than that of age-matched controls, thus making evaluation for coronary artery disease important in this patient population. The purpose of this study was to evaluate the image quality of a comprehensive CTA protocol in patients with acute stroke that expands the standard CTA coverage to include all 4 chambers of the heart and the coronary arteries.One hundred twenty patients consecutively admitted to the emergency department with suspected cerebrovascular ischemia undergoing standard-of-care CTA were prospectively enrolled in our study. We used an original tailored acquisition protocol using a 64-section CT scanner, consisting of a dual-phase intravenous injection of iodinated contrast and saline flush, in conjunction with a dual-phase CT acquisition, ascending from the top of the aortic arch to the vertex of the head, then descending from the top of the aortic arch to the diaphragm. No beta blockers were administered. The image quality, attenuation, and CNRs of the carotid, aortic, vertebral, and coronary arteries were assessed.Carotid, aorta, and vertebral artery image quality was 100% diagnostic (rated good or excellent) in all patients. Coronary artery image quality was diagnostic in 58% of RCA segments, 73% of LAD segments, and 63% of LCX segments. When we considered proximal segments only, the diagnostic quality rose to 71% in the RCA, 83% in the LAD, and 74% in the LCX.Our stroke protocol achieved excellent opacification of the left heart chambers, the cervical arteries, and each coronary artery, in addition to adequate carotid and coronary artery image quality.

    View details for DOI 10.3174/ajnr.A2075

    View details for Web of Science ID 000281106700026

    View details for PubMedID 20360341

  • Optimal carotid artery coverage for carotid plaque CT-imaging in predicting ischemic stroke JOURNAL OF NEURORADIOLOGY Arora, S., Chien, J. D., Cheng, S., Chun, K. A., Wintermark, M. 2010; 37 (2): 98-103

    Abstract

    To determine the optimal spatial coverage for CT-imaging of carotid atherosclerosis, allowing the most accurate prediction of the associated risk of ischemic stroke.In a cross-sectional study, we retrospectively identified 136 consecutive patients admitted to our emergency department with suspected stroke who underwent a CT-angiogram (CTA) of the cervical and intracranial carotid arteries. CTA studies of the carotid arteries were processed using a custom, CT-based automated computer classifier algorithm that quantitatively assesses a battery of carotid CT features. We used this algorithm to individually analyze different lengths of the common and internal carotid arteries for carotid wall features previously shown to be significantly associated with the risk of stroke. Acute stroke patients were categorized into "acute carotid stroke patients" and "non-acute carotid stroke patients" independently of carotid wall CT features. Univariate and multivariate analyses were used to compare the different spatial coverages in terms of their ability to distinguish between the carotid stroke patients and the noncarotid stroke patients using a receiver-operating characteristic curve (ROC) approach.The carotid wall volume was excellent at distinguishing between carotid stroke patients and noncarotid stroke patients, especially for coverages 20mm or less. The number and location of lipid clusters had a good discrimination power, mainly for coverages 15mm or greater. Measurement of minimal fibrous cap thickness was most associated with carotid stroke when assessed using intermediate coverages. Typically, a 20mm coverage on each side of the carotid bifurcation offered the optimal compromise between the individual carotid features.We recommend assessment of 20mm of each side of the carotid bifurcation to best characterize carotid atherosclerotic disease and the associated risk of ischemic stroke.

    View details for DOI 10.1016/j.neurad.2009.04.002

    View details for Web of Science ID 000278330200004

    View details for PubMedID 19573923

  • MR and CT Monitoring of Recanalization, Reperfusion, and Penumbra Salvage Everything That Recanalizes Does Not Necessarily Reperfuse! STROKE Soares, B. P., Chien, J. D., Wintermark, M. 2009; 40 (3): S24-S27

    Abstract

    Revascularization therapies for acute stroke patients aim to rescue the ischemic penumbra by restoring the patency of the occluded artery ("recanalization") and the downstream capillary blood flow ("reperfusion"). This article reviews the definition of recanalization and reperfusion used in stroke clinical trials and their limitations and proposes a study design to determine the relative importance of recanalization, reperfusion, and collateral flow in evaluating the efficacy of revascularization therapies for acute ischemic stroke.

    View details for DOI 10.1161/STROKEAHA.108.526814

    View details for Web of Science ID 000263594200008

    View details for PubMedID 19064812

  • Cerebral perfusion CT: Technique and clinical applications JOURNAL OF NEURORADIOLOGY Wintermark, M., Sincic, R., Sridhar, D., Chien, J. D. 2008; 35 (5): 253-260

    Abstract

    Perfusion computed tomography (PCT) is an imaging technique that allows rapid, noninvasive, quantitative evaluation of cerebral perfusion by generating maps of cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT). The concepts behind this imaging technique were developed in the 1980s', but its widespread clinical use was allowed by the recent introduction of rapid, large-coverage multidetector-row CT scanners. Key clinical applications for PCT include the diagnosis of cerebral ischemia and infarction, and evaluation of vasospasm after subarachnoid hemorrhage. PCT measurements of cerebrovascular reserve after acetazolamide challenges in patients with vascular stenoses permit evaluation of candidacy for bypass surgery and endovascular treatment. PCT has also been used to assess cerebral perfusion after head trauma and microvascular permeability in the setting of intracranial neoplasm. Some controversy exists regarding this technique, including questions regarding correct selection of an arterial input vessel, the accuracy of quantitative results, and the reproducibility of results. This article provides an overview of PCT, including details of technique, major clinical applications, and limitations.

    View details for DOI 10.1016/j.neurad.2008.03.005

    View details for Web of Science ID 000261970400001

    View details for PubMedID 18466974

  • Perfusion CT compared to (H2O)-O-15/(OO)-O-15 PET in patients with chronic cervical carotid artery occlusion NEURORADIOLOGY Kamath, A., Smith, W. S., Powers, W. J., Cianfoni, A., Chien, J. D., Videen, T., Lawton, M. T., Finley, B., Dillon, W. P., Wintermark, M. 2008; 50 (9): 745-751

    Abstract

    The purpose of this study was to compare the results of perfusion computed tomography (PCT) with those of (15)O(2)/H(2) (15)O positron emission tomography (PET) in a subset of Carotid Occlusion Surgery Study (COSS) patients.Six patients enrolled in the COSS underwent a standard-of-care PCT in addition to the (15)O(2)/H(2) (15)O PET study used for selection for extracranial-intracranial bypass surgery. PCT and PET studies were coregistered and then processed separately by different radiologists. Relative measurement of cerebral blood flow (CBF) and oxygen extraction fraction (OEF) were calculated from PET. PCT datasets were processed using different arterial input functions (AIF). Relative PCT and PET CBF values from matching regions of interest were compared using linear regression model to determine the most appropriate arterial input function for PCT. Also, PCT measurements using the most accurate AIF were evaluated for linear regression with respect to relative PET OEF values.The most accurate PCT relative CBF maps with respect to the gold standard PET CBF were obtained when CBF values for each arterial territory are calculated using a dedicated AIF for each territory (R (2) = 0.796, p < 0.001). PCT mean transit time (MTT) is the parameter that showed the best correlation with the count-based PET OEF ratios (R (2) = 0.590, p < 0.001).PCT relative CBF compares favorably to PET relative CBF in patients with chronic carotid occlusion when processed using a dedicated AIF for each territory. The PCT MTT parameter correlated best with PET relative OEF.

    View details for DOI 10.1007/s00234-008-0403-9

    View details for Web of Science ID 000259008400001

    View details for PubMedID 18509627

  • Carotid plaque computed tomography imaging in stroke and nonstroke patients ANNALS OF NEUROLOGY Wintermark, M., Arora, S., Tong, E., Vittinghoff, E., Lau, B. C., Chien, J. D., Dillon, W. P., Saloner, D. 2008; 64 (2): 149-157

    Abstract

    To identify a set of computed tomographic (CT) features of carotid atherosclerotic plaques that is significantly associated with ischemic stroke.In a cross-sectional study, we retrospectively identified 136 consecutive patients admitted to our emergency department with suspected stroke who underwent a CT-angiogram of the carotid arteries. CT-angiographic studies of the carotid arteries were processed automatically using automated computer classifier algorithm that quantitatively assesses a battery of carotid CT features. Acute stroke patients were categorized into "acute carotid stroke patients" and "nonacute carotid stroke patients" independent of carotid wall CT features, using the Causative Classification System for Ischemic Stroke, which includes the neuroradiologist's review of the imaging studies of the brain parenchyma and of the degree of carotid stenosis, and charted test results (such as electrocardiogram). Univariate followed by multivariate analyses were used to build models to differentiate between these patient groups and to differentiate between the infarct and unaffected sides in the "acute carotid stroke patients."Forty "acute carotid stroke" patients and 50 "nonacute carotid stroke" patients were identified. Multivariate modeling identified a small number of the carotid wall CT features that were significantly associated with acute carotid stroke, including wall volume, fibrous cap thickness, number and location of lipid clusters, and number of calcium clusters.Patients with acute carotid stroke demonstrate significant differences in the appearance of their carotid wall ipsilateral to the side of their infarct, when compared with either nonacute carotid stroke patients or the carotid wall contralateral with the infarct side.

    View details for DOI 10.1002/ana.21424

    View details for Web of Science ID 000258921800006

    View details for PubMedID 18756475

  • Semi-automated computer assessment of the degree of carotid artery stenosis compares favorably to visual evaluation JOURNAL OF THE NEUROLOGICAL SCIENCES Wintermark, M., Glastonbury, C., Tong, E., Lau, B. C., Schaeffer, S., Chien, J. D., Haar, P. J., Saloner, D. 2008; 269 (1-2): 74-79

    Abstract

    To validate a semi-automated computer approach for the assessment of the degree of carotid artery luminal narrowing by comparing it to the visual evaluation by a neuroradiologist.In a retrospective cross-sectional study, consecutive emergency department patients who underwent computed tomography angiography (CTA) of the carotid arteries were identified. CTA studies were reviewed by a neuroradiologist, and also independently processed with a computer algorithm that automatically measures the degree of luminal narrowing at the level of the internal carotid artery bulb. The findings of the neuroradiologist and computer assessment were compared using Chi2 tests/kappa calculations and linear regression for categorical and continuous measurements of carotid stenosis, respectively.The study population consisted of 125 patients (74 no stroke/TIA, 18TIA, and 33 stroke). 201 carotid arteries showed no significant stenosis; 33 showed > or =70% stenosis, 5 showed 95-99% stenosis, and 11 showed complete occlusion. There was excellent agreement between the neuroradiologist's visual assessment and the automated computer evaluation of the category of carotid stenosis (kappa=0.918, p<0.001).The automated computer algorithm for quantifying the degree of carotid stenosis is reliable and shows high concordance with the interpretation of an experienced neuroradiologist.

    View details for DOI 10.1016/j.jns.2007.12.023

    View details for Web of Science ID 000256208500012

    View details for PubMedID 18234230

  • The anterior cerebral artery is an appropriate arterial input function for perfusion-CT processing in patients with acute stroke NEURORADIOLOGY Wintermark, M., Lau, B. C., Chien, J., Arora, S. 2008; 50 (3): 227-236

    Abstract

    Dynamic perfusion-CT (PCT) with deconvolution requires an arterial input function (AIF) for postprocessing. In clinical settings, the anterior cerebral artery (ACA) is often chosen for simplicity. The goals of this study were to determine how the AIF selection influences PCT results in acute stroke patients and whether the ACA is an appropriate default AIF.We retrospectively identified consecutive patients suspected of hemispheric stroke of less than 48 h duration who were evaluated on admission by PCT. PCT datasets were postprocessed using multiple AIF, and cerebral blood volume (CBV) and flow (CBF), and mean transit time (MTT) values were measured in the corresponding territories. Results from corresponding territories in the same patients were compared using paired t-tests. The volumes of infarct core and tissue at risk obtained with different AIFs were compared to the final infarct volume.Of 113 patients who met the inclusion criteria, 55 with stroke were considered for analysis. The MTT values obtained with an "ischemic" AIF tended to be shorter (P=0.055) and the CBF values higher (P=0.108) than those obtained using a "nonischemic" AIF. CBV values were not influenced by the selection of the AIF. No statistically significant difference was observed between the size of the PCT infarct core (P=0.121) and tissue at risk (P=0.178), regardless of AIF selection.In acute stroke patients, the selection of the AIF has no statistically significant impact of the PCT results; standardization of the PCT postprocessing using the ACA as the default AIF is adequate.

    View details for DOI 10.1007/s00234-007-0336-8

    View details for Web of Science ID 000253522800005

    View details for PubMedID 18057929

  • Visual grading system for vasospasm based on perfusion CT imaging: Comparisons with conventional angiography and quantitative perfusion CT CEREBROVASCULAR DISEASES Wintermark, M., Dillon, W. P., Smith, W. S., Lau, B. C., Chaudhary, S., Liu, S., Yu, M., Fitch, M., Chien, J. D., Higashida, R. T., Ko, N. U. 2008; 26 (2): 163-170

    Abstract

    The purpose of this study was to compare simple visual grading of perfusion CT (PCT) maps to a more quantitative, threshold-based interpretation of PCT parameters in the characterization of presence and severity of vasospasm.Thirty-three patients with acute subarachnoid hemorrhage were enrolled in a prospective study and underwent a total of 40 paired PCT and digital subtraction angiography (DSA) examinations. A neuroradiologist and a neurologist reviewed the PCT mean transit time (MTT), cerebral blood flow (CBF), and cerebral blood volume maps independently; they evaluated five anatomical regions (frontal, temporal, parietal, occipital/thalami, and basal ganglia/insula) and graded them for abnormality (0 if normal, 1 if abnormal in <50% of the region, and 2 if abnormal in >or=50% of the region). A third neuroradiologist blinded to the PCT results reviewed the DSA examinations and assessed 19 segments for the presence or absence of vasospasm. Correlation between PCT and DSA scores was assessed, as well as the sensitivity and specificity of PCT compared to DSA used as a gold standard.MTT (R(2) = 0.939) and CBF (R(2) = 0.907) scores correlated best with DSA scores (p < 0.001). MTT scoring had a sensitivity of 92% and a specificity of 86% compared to DSA; CBF scoring had a sensitivity of 75% and a specificity of 95%. The interobserver agreement between neuroradiologist and neurologist was found to have kappa = 0.789 for MTT and 0.658 for CBF.We propose a user-friendly visual grading system for PCT maps in patients with suspected vasospasm. This visual approach compares favorably to the results of DSA. Sensitive MTT maps should be used for screening, and specific CBF maps for confirmation of vasospasm.

    View details for DOI 10.1159/000139664

    View details for Web of Science ID 000259725400010

    View details for PubMedID 18560220