H. Henry Guo, MD, PhD

All Publications

• Evaluation of integrin alphavbeta6 cystine knot PET tracers to detect cancer and idiopathic pulmonary fibrosis. Nature communications Kimura, R. H., Wang, L., Shen, B., Huo, L., Tummers, W., Filipp, F. V., Guo, H. H., Haywood, T., Abou-Elkacem, L., Baratto, L., Habte, F., Devulapally, R., Witney, T. H., Cheng, Y., Tikole, S., Chakraborti, S., Nix, J., Bonagura, C. A., Hatami, N., Mooney, J. J., Desai, T., Turner, S., Gaster, R. S., Otte, A., Visser, B. C., Poultsides, G. A., Norton, J., Park, W., Stolowitz, M., Lau, K., Yang, E., Natarajan, A., Ilovich, O., Srinivas, S., Srinivasan, A., Paulmurugan, R., Willmann, J., Chin, F. T., Cheng, Z., Iagaru, A., Li, F., Gambhir, S. S. 2019; 10 (1): 4673

  Abstract

  Advances in precision molecular imaging promise to transform our ability to detect, diagnose and treat disease. Here, we describe the engineering and validation of a new cystine knot peptide (knottin) that selectively recognizes human integrin alphavbeta6 with single-digit nanomolar affinity. We solve its 3D structure by NMR and x-ray crystallography and validate leads with 3 different radiolabels in pre-clinical models of cancer. We evaluate the lead tracer's safety, biodistribution and pharmacokinetics in healthy human volunteers, and show its ability to detect multiple cancers (pancreatic, cervical and lung) in patients at two study locations. Additionally, we demonstrate that the knottin PET tracers can also detect fibrotic lung disease in idiopathic pulmonary fibrosis patients. Our results indicate that these cystine knot PET tracers may have potential utility in multiple disease states that are associated with upregulation of integrin alphavbeta6.

  View details for DOI 10.1038/s41467-019-11863-w

  View details for PubMedID 31611594

• Thoracic Radiologists' Versus Computer Scientists' Perspectives on the Future of Artificial Intelligence in Radiology. Journal of thoracic imaging Eltorai, A. E., Bratt, A. K., Guo, H. H. 2019

  Abstract

  BACKGROUND: There is intense interest and speculation in the application of artificial intelligence (AI) to radiology. The goals of this investigation were (1) to assess thoracic radiologists' perspectives on the role and expected impact of AI in radiology, and (2) to compare radiologists' perspectives with those of computer science (CS) experts working in the AI development.METHODS: An online survey was developed and distributed to chest radiologists and CS experts at leading academic centers and societies, comparing their expectations of AI's influence on radiologists' jobs, job satisfaction, salary, and role in society.RESULTS: A total of 95 radiologists and 45 computer scientists responded. Computer scientists reported having read more scientific journal articles on AI/machine learning in the past year than radiologists (mean [95% confidence interval]=17.1 [9.01-25.2] vs. 7.3 [4.7-9.9], P=0.0047). The impact of AI in radiology is expected to be high, with 57.8% and 73.3% of computer scientists and 31.6% and 61.1% of chest radiologists predicting radiologists' job will be dramatically different in 5 to 10 years, and 10 to 20 years, respectively. Although very few practitioners in both fields expect radiologists to become obsolete, with 0% expecting radiologist obsolescence in 5 years, in the long run, significantly more computer scientists (15.6%) predict radiologist obsolescence in 10 to 20 years, as compared with 3.2% of radiologists reporting the same (P=0.0128). Overall, both chest radiologists and computer scientists are optimistic about the future of AI in radiology, with large majorities expecting radiologists' job satisfaction to increase or stay the same (89.5% of radiologists vs. 86.7% of CS experts, P=0.7767), radiologists' salaries to increase or stay the same (83.2% of radiologists vs. 73.4% of CS experts, P=0.1827), and the role of radiologists in society to improve or stay the same (88.4% vs. 86.7%, P=0.7857).CONCLUSIONS: Thoracic radiologists and CS experts are generally positive on the impact of AI in radiology. However, a larger percentage, but still small minority, of computer scientists predict radiologist obsolescence in 10 to 20 years. As the future of AI in radiology unfolds, this study presents a historical timestamp of which group of experts' perceptions were closer to eventual reality.

  View details for DOI 10.1097/RTI.0000000000000453

  View details for PubMedID 31609778

• Single-Lumen Endotracheal Tube and Bronchial Blocker for Airway Management During Tracheobronchoplasty for Tracheobronchomalacia: A Case Report. A&A practice Lui, N. S., Guo, H. H., Sung, A. W., Peterson, A., Kulkarni, V. N. 2019

  Abstract

  We present a case of a 69-year-old man who underwent tracheobronchoplasty for tracheobronchomalacia using a single-lumen endotracheal tube and a Y-shaped bronchial blocker for airway management. Tracheobronchoplasty is performed by sewing mesh to plicate the posterior, membranous wall of the distal trachea and main bronchi through a right posterolateral thoracotomy. The goals of airway management include continuous left-lung ventilation and lung protection from aspiration. Ideally, only conventional airway management tools are used. This case demonstrates that a single-lumen endotracheal tube with a bronchial blocker can be a straightforward strategy for airway management during tracheobronchoplasty.

  View details for DOI 10.1213/XAA.0000000000001076

  View details for PubMedID 31385817

• A Young Woman With a Rapidly GrowingThoracic Tumor. Chest Lai, Y. K., Holmes, B., Guo, H. H. 2019; 155 (5): e145–e148

  Abstract

  CASE PRESENTATION: A 38-year-old woman presented with 2months of dry cough, progressiveshortness of breath, central chest pain, nausea, vomiting, and dizziness. She was previously healthy and was not taking any medications. She denied fever, night sweats, or weight loss. She had a two pack-year smoking history and had quit smoking at 27 years of age. She denied drug use and had no recent travel history. Family history was pertinent for ovarian cancer, breast cancer, and colon cancer.

  View details for DOI 10.1016/j.chest.2018.12.014

  View details for PubMedID 31060712

• Serial Cardiac FDG-PET for the Diagnosis and Therapeutic Guidance of Patients With Cardiac Sarcoidosis JOURNAL OF CARDIAC FAILURE Ning, N., Guo, H., Iagaru, A., Mittra, E., Fowler, M., Witteles, R. 2019; 25 (4): 307–11

  View details for DOI 10.1016/j.cardfail.2019.02.018

  View details for Web of Science ID 000466060500013

• The Intralobular Gradient as Seen in Re-Expansion Pulmonary Edema Radiology: Cardiothoracic Imaging Lai, Y. K., Lindholm, P., Guo, H. H. 2019; 1 (5): 1

  View details for DOI 10.1148/ryct.2019190084

• Left Atrial Volume as a Biomarker of Atrial Fibrillation at Routine Chest CT: Deep Learning Approach Radiology: Cardiothoracic Imaging Bratt, A., Guenther, Z., Lewis, H., Kadoch, M., Adams, P. L., Leung, A. N., Guo, H. H. 2019; 1 (5): 1-7

  View details for DOI 10.1148/ryct.2019190057

• 3D Printing and the Cystic Fibrosis Lung. Journal of cystic fibrosis : official journal of the European Cystic Fibrosis Society Mirza, A. A., Robinson, T. E., Gifford, K., Guo, H. H. 2018

  View details for PubMedID 30361143

• Synchronous primary lung adenocarcinomas harboring distinct MET Exon 14 splice site mutations. Lung cancer (Amsterdam, Netherlands) Wang, S. X., Lei, L., Guo, H. H., Shrager, J., Kunder, C. A., Neal, J. W. 2018; 122: 187–91

  Abstract

  When a patient is found to have multiple lung tumors, distinguishing whether they represent metastatic nodules or separate primary cancers is crucial for staging and therapy. We report the case of a 79-year-old patient with two surgically resected synchronous left upper lobe adenocarcinomas initially pathologically staged as T3 (IIB), indicating adjuvant chemotherapy should be recommended. However, the tumors appeared radiographically distinct, so next-generation sequencing was performed on each nodule. Each tumor harbored a different mesenchymal-to-epithelial transition (MET) exon 14 skipping mutation, an emerging targetable mutation, suggestive of distinct clonality. While the in frame protein deletion was the same in each tumor, the nucleotide base substitutions were different. Thus, the patient was down-staged to having two separate IA tumors, spared of adjuvant chemotherapy, and routine surveillance was recommended. This case highlights the utility of using molecular analysis in diagnosing and treating multifocal lung tumors, and the process of convergent molecular evolution toward a common oncogenic driver mutation. This is the first case of multiple synchronous lung tumors each harboring a distinct MET exon 14 splice site mutation.

  View details for PubMedID 30032829

• SERIAL CARDIAC FDG-PET IN THE DIAGNOSIS AND THERAPEUTIC GUIDANCE OF PATIENTS WITH CARDIAC SARCOIDOSIS: A STANFORD EXPERIENCE Ning, N., Guo, H. H., Jagaru, A., Mittra, E., Fowler, M., Witteles, R. ELSEVIER SCIENCE INC. 2018: 1690

  View details for DOI 10.1016/S0735-1097(18)32231-9

  View details for Web of Science ID 000429659703340

• Prognostic Value of Pretreatment FDG-PET Parameters in High-dose Image-guided Radiotherapy for Oligometastatic Non-Small-cell Lung Cancer. Clinical lung cancer Chin, A. L., Kumar, K. A., Guo, H. H., Maxim, P. G., Wakelee, H., Neal, J. W., Diehn, M., Loo, B. W., Gensheimer, M. F. 2018

  Abstract

  Emerging data support aggressive local treatment of oligometastatic non-small-cell lung cancer (NSCLC) patients. We sought to determine whether the metabolic burden of disease found by fluorodeoxyglucose positron emission tomography at the time of high-dose radiotherapy (RT) for oligometastatic NSCLC can serve as a prognostic biomarker.We conducted a retrospective cohort study of 67 RT treatment courses in 55 patients with oligometastatic NSCLC who had undergone high-dose RT to all sites of active disease at our institution. The metabolic tumor volume, total lesion glycolysis (TLG), and maximum standardized uptake value of all lesions were measured on the pretreatment fluorodeoxyglucose positron emission tomography scans. Cox regression analysis was used to assess the influence of imaging and clinical factors on overall survival (OS).On univariate analysis, a greater metabolic tumor volume and TLG were predictive of shorter OS (hazard ratio of death, 2.42 and 2.14, respectively; P = .009 and P = .004, respectively). The effects remained significant on multivariate analysis. Neither the maximum standardized uptake value nor the number of lesions was significantly associated with OS. Patients within the highest quartile of TLG values (> 86.8 units) had a shorter median OS than those within the lower 3 quartiles (12.4 vs. 30.1 months; log-rank P = .014).The metabolic tumor burden was prognostic of OS and might help to better select oligometastatic NSCLC patients for locally ablative therapy.

  View details for PubMedID 29759331

• From Ocean Deep to Mountain High: Similar Computed Tomography Findings in Immersion and High-Altitude Pulmonary Edema. American journal of respiratory and critical care medicine Lindholm, P., Swenson, E. R., Martínez-Jiménez, S., Guo, H. H. 2018; 198 (8): 1088–89

  View details for DOI 10.1164/rccm.201803-0581IM

  View details for PubMedID 30044644

• Improving Quality of Dynamic Airway Computed Tomography Using an Expiratory Airflow Indicator Device. Journal of thoracic imaging Hahn, L. D., Sung, A. W., Shafiq, M., Guo, H. H. 2018

  Abstract

  Dynamic computed tomography (CT) of the airways is increasingly used to evaluate patients with suspected expiratory central airway collapse, but current protocols are susceptible to inadequate exhalation caused by variable patient compliance with breathing instructions during the expiratory phase. We developed and tested a low-cost single-use expiratory airflow indicator device that was designed to improve study quality by providing a visual indicator to both patient and operator when adequate expiratory flow was attained.A total of 56 patients undergoing dynamic airway CT were evaluated, 35 of whom were scanned before introduction of the indicator device (control group), with the rest comprising the intervention group. Lung volumes and tracheal cross-sectional areas on inspiratory/expiratory phases were computed using automated lung segmentation and quantitative software analysis. Inadequate exhalation was defined as absolute volume change of <500 mL during the expiratory phase.Fewer patients in the intervention group demonstrated inadequate exhalation. The average change in volume was higher in the intervention group (P=0.004), whereas the average minimum tracheal cross-sectional area was lower (P=0.01).The described expiratory airflow indicator device can be used to ensure adequate exhalation during the expiratory phase of dynamic airway CT. A higher frequency of adequate exhalation may improve reliability and sensitivity of dynamic airway CT for diagnosis of expiratory central airway collapse.

  View details for PubMedID 29470258

• Initial Experience With Simultaneous 18F-FDG PET/MRI in the Evaluation of Cardiac Sarcoidosis and Myocarditis. Clinical nuclear medicine Hanneman, K., Kadoch, M., Guo, H. H., Jamali, M., Quon, A., Iagaru, A., Herfkens, R. 2017; 42 (7): e328-e334

  Abstract

  The purpose of this study was to compare combined PET/MRI with PET/CT and cardiac MRI in the evaluation of cardiac sarcoidosis and myocarditis.Ten patients (4 men and 6 women; 56.1 ± 9.6 years old) were prospectively enrolled for evaluation of suspected cardiac sarcoidosis or myocarditis. Written informed consent was obtained. Following administration of 9.9 ± 0.9 mCi F-FDG, patients underwent standard cardiac PET/CT followed by combined PET/MRI using a simultaneous 3-T scanner. Cardiac MRI sequences included ECG-triggered cine SSFP, T2-weighted, and late gadolinium-enhanced imaging. Myocardial involvement was assessed with separate analysis of combined PET/MRI, PET/CT, and cardiac MRI data using dedicated postprocessing software. Estimates of radiation dose were derived from the applied doses of F-FDG and CT protocol parameters.Imaging was acquired with a delay from F-FDG injection of 90.2 ± 27.4 minutes for PET/CT and 207.7 ± 40.3 minutes for PET/MRI. Total scan time for PET/MRI was significantly longer than for PET/CT (81.4 ± 14.8 vs 12.0 minutes, P < 0.001). Total effective radiation dose was significantly lower for PET/MRI compared with PET/CT (6.9 ± 0.6 vs 8.2 ± 1.1 mSv, P = 0.007). There was no significant difference in the number of positive cases identified between combined PET/MRI (n = 10 [100%]), PET/CT (n = 6 [60%]), and cardiac MRI (n = 8 [80%]), P = 0.091.Simultaneous cardiac PET/MRI is feasible in the evaluation of cardiac sarcoidosis and myocarditis achieving diagnostic image quality.

  View details for DOI 10.1097/RLU.0000000000001669

  View details for PubMedID 28418949

• Identification of Pulmonary Hypertension Caused by Left Heart Disease (World Health Organization Group 2) Based on Cardiac Chamber Volumes Derived from Chest CT. Chest Aviram, G., Rozenbaum, Z., Ziv-Baran, T., Berliner, S., Topilsky, Y., Fleischmann, D., Sung, Y. K., Zamanian, R. T., Guo, H. H. 2017

  Abstract

  Evaluations of patients with pulmonary hypertension (PH) commonly include chest computed tomography (CT). We hypothesized that cardiac chamber volumes calculated from the same CT scans can yield additional information to distinguish left heart disease-related PH (WHO Group 2) from other PH subtypes.Patients with right heart catheterization (RHC)-confirmed PH and contrast-enhanced chest CT studies were enrolled in this retrospective multicenter study. Cardiac chamber volumes were calculated using automated segmentation software and compared between Group 2 and non-Group 2 PH patients.This study included 114 PH patients, of whom 27 (24%) were classified as Group 2 based on their pulmonary capillary wedge pressure. Group 2 PH patients exhibited significantly larger median left atrial (LA) volumes (118 vs. 63 mL, P < 0.001), larger median left ventricular (LV) volumes (90 vs. 76 mL, P = 0.02), and smaller median right ventricular (RV) volumes (173 vs. 210 mL, P = 0.005) than non-Group 2 patients. On multivariate analysis adjusted to age, gender, and mean pulmonary arterial pressure, Group 2 PH was significantly associated with larger median LA and LV volumes (P < 0.001 and P = 0.008, respectively), and decreased volume ratios of RA/LA, RV/LV and RV/LA (P = 0.001, P = 0.004, and P < 0.001, respectively). Enlarged LA volumes demonstrated high discriminatory ability for Group 2 PH (AUC=0.92; 95%CI, 0.870-0.968).Volumetric analysis of the cardiac chambers from non-gated chest CTs, particularly with findings of an enlarged LA, exhibited high discriminatory ability for identifying patients with PH due to left heart disease.

  View details for DOI 10.1016/j.chest.2017.04.184

  View details for PubMedID 28506612

• Pulmonary function after lung tumor stereotactic ablative radiotherapy depends on regional ventilation within irradiated lung. Radiotherapy and oncology Binkley, M. S., King, M. T., Shrager, J. B., Bush, K., Chaudhuri, A. A., Popat, R., Gensheimer, M. F., Maxim, P. G., Henry Guo, H., Diehn, M., Nair, V. S., Loo, B. W. 2017; 123 (2): 270-275

  Abstract

  To determine if regional ventilation within irradiated lung volume predicts change in pulmonary function test (PFT) measurements after stereotactic ablative radiotherapy (SABR) of lung tumors.We retrospectively identified 27 patients treated from 2007 to 2014 at our institution who received: (1) SABR without prior thoracic radiation; (2) pre-treatment 4-dimensional computed tomography (4-D CT) imaging; (3) pre- and post-SABR PFTs <15months from treatment. We defined the ventilation ratio (VR20BED3) as the quotient of mean ventilation (mean Jacobian-based per-voxel volume change on deformably registered inhale/exhale 4-D CT phases) within the 20Gy biologically effective dose (α/β=3Gy) isodose volume and that of the total lung volume (TLV).Most patients had moderate to very severe COPD by GOLD criteria (n=19, 70.1%). Higher VR20BED3 significantly predicted worse change in Forced Expiratory Volume/s normalized by baseline value (ΔFEV1/FEV1pre, p=0.04); n=7 had VR20BED3>1 (high regional ventilation) and worse ΔFEV1/FEV1pre (median=-0.16, range=-0.230 to -0.20). Five had VR20BED3<1 (low regional ventilation) and improved ΔFEV1/FEV1pre (median=0.13, range=0.07 to 0.20). In a multivariable linear model, increasing VR20BED3 and time to post-SABR PFT predicted decreasing ΔFEV1/FEV1pre (R(2)=0.25, p=0.03).After SABR to high versus low functioning lung regions, we found worsened or improved global pulmonary function, respectively. If pre-SABR VR20BED3 is validated as a predictor of eventual post-SABR PFT in larger studies, it may be used for individualized treatment planning to preserve or even improve pulmonary function after SABR.

  View details for DOI 10.1016/j.radonc.2017.03.021

  View details for PubMedID 28460826

• Left Atrium Maximal Axial Cross-Sectional Area is a Specific Computed Tomographic Imaging Biomarker of World Health Organization Group 2 Pulmonary Hypertension. Journal of thoracic imaging Jivraj, K., Bedayat, A., Sung, Y. K., Zamanian, R. T., Haddad, F., Leung, A. N., Rosenberg, J., Guo, H. H. 2017; 32 (2): 121-126

  Abstract

  Left heart disease is associated with left atrial enlargement and is a common cause of pulmonary hypertension (PH). We investigated the relationship between left atrium maximal axial cross-sectional area (LA-MACSA), as measured on chest computed tomography (CT), and PH due to left heart disease (World Health Organization group 2) in patients with right heart catheterization-proven PH.A total of 165 patients with PH who had undergone right heart catheterization with pulmonary artery pressure and pulmonary capillary wedge pressure (PCWP) measurements and nongated chest CTs were included. LA-MACSA, LA anterior-posterior, and LA transverse measurements were independently obtained using the hand-drawn region-of-interest and distance measurement tools on standard PACS by 2 blinded cardiothoracic radiologists. Nonparametric statistical analyses and receiver operating characteristic curve were performed.Forty-three patients had group 2 PH (PCWP>15 mm Hg), and 122 had nongroup 2 PH (PCWP≤15 mm Hg). Median LA-MACSA was significantly different between the group 2 PH and nongroup 2 PH patients (2312 vs. 1762 mm, P<0.001). Interobserver concordance correlation for LA-MACSA was high at 0.91 (P<0.001). At a threshold of 2400 mm, LA-MACSA demonstrated 93% specificity for classifying group 2 PH (area under the curve, 0.73; P<0.001).LA-MACSA is a readily obtainable and reproducible measurement of left atrial enlargement on CT and can distinguish between group 2 and nongroup 2 PH with high specificity.

  View details for DOI 10.1097/RTI.0000000000000252

  View details for PubMedID 28009778

• Predictive radiogenomics modeling of EGFR mutation status in lung cancer SCIENTIFIC REPORTS Gevaert, O., Echegaray, S., Khuong, A., Hoang, C. D., Shrager, J. B., Jensen, K. C., Berry, G. J., Guo, H. H., Lau, C., Plevritis, S. K., Rubin, D. L., Napel, S., Leung, A. N. 2017; 7

  Abstract

  Molecular analysis of the mutation status for EGFR and KRAS are now routine in the management of non-small cell lung cancer. Radiogenomics, the linking of medical images with the genomic properties of human tumors, provides exciting opportunities for non-invasive diagnostics and prognostics. We investigated whether EGFR and KRAS mutation status can be predicted using imaging data. To accomplish this, we studied 186 cases of NSCLC with preoperative thin-slice CT scans. A thoracic radiologist annotated 89 semantic image features of each patient's tumor. Next, we built a decision tree to predict the presence of EGFR and KRAS mutations. We found a statistically significant model for predicting EGFR but not for KRAS mutations. The test set area under the ROC curve for predicting EGFR mutation status was 0.89. The final decision tree used four variables: emphysema, airway abnormality, the percentage of ground glass component and the type of tumor margin. The presence of either of the first two features predicts a wild type status for EGFR while the presence of any ground glass component indicates EGFR mutations. These results show the potential of quantitative imaging to predict molecular properties in a non-invasive manner, as CT imaging is more readily available than biopsies.

  View details for DOI 10.1038/srep41674

  View details for PubMedID 28139704

• Coccidioidomycosis: Surgical Issues and Implications. Surgical infections Forrester, J. D., Guo, H. H., Weiser, T. G. 2016: -?

  Abstract

  Coccidioidomycosis, commonly called "valley fever," "San Joaquin fever," "desert fever," or "desert rheumatism," is a multi-system illness caused by infection with Coccidioides fungi (C. immitis or C. posadasii). This organism is endemic to the desert Southwest regions of the United States and Mexico and to parts of South America. The manifestations of infection occur along a spectrum from asymptomatic to mild self-limited fever to severe disseminated disease.Review of the English-language literature.There are five broad indications for surgical intervention in patients with coccidioidomycosis: Tissue diagnosis in patients at risk for co-existing pathology, perforation, bleeding, impingement on critical organs, and failure to resolve with medical management. As part of a multidisciplinary team, surgeons may be responsible for the care of infected patients, particularly those with severe disease.This review discusses the history, microbiology, epidemiology, pathology, diagnosis, and treatment of coccidioidomycosis, focusing on situations that may be encountered by surgeons.

  View details for PubMedID 27740893

• Clinical significance of extraskeletal computed tomography findings on 18F-NaF PET/CT performed for osseous metastatic disease evaluation. Nuclear medicine communications Guo, H. H., Moradi, F., Iagaru, A. 2016; 37 (9): 975-982

  Abstract

  Extraskeletal findings detected on whole-body low-dose unenhanced computed tomography (CT) as a part of F-NaF PET/CT scans can be numerous and present challenges for further management. Here, we investigate the frequency and clinical significance of extraskeletal findings among 130 consecutive patients undergoing F-NaF PET/CT for osseous metastatic disease.F-NaF PET/CT performed on 130 patients (101 men and 29 women; mean age: 61.4 years) with biopsy-proven malignancies were reviewed independently. Incidental soft tissue findings detected on unenhanced low-dose CT portions of the scans were compiled and categorized by clinical significance.A total of 275 incidental extraskeletal CT findings were observed in 114 out of 130 patients (87.7%). Seven patients (5.4%) showed clinically significant findings. One patient developed new lung nodules that were resected and proven to be metastases. Two patients showed new hypodense hepatic lesions that were highly suspicious for liver metastases. One patient with prostate cancer was found to have previously unknown retroperitoneal lymphadenopathy. Three patients showed indeterminate renal and adrenal lesions that necessitated further correlative imaging.Although CT indicated a large number of incidental extraskeletal lesions in the majority of patients undergoing F-NaF PET/CT, clinically significant incidental findings requiring further evaluation were relatively infrequently observed in 5.4% of patients. Thus, the low-dose unenhanced CT in F-NaF PET/CT performed for oncologic evaluation may indicate unexpected soft tissue lesions that can impact patient management and therefore should be interpreted by physicians skilled in CT reading, with correlation to available imaging, and familiar with established guidelines for work-up of incidental findings.

  View details for DOI 10.1097/MNM.0000000000000531

  View details for PubMedID 27111100

• A Wandering Pulmonary Nodule. American journal of respiratory and critical care medicine Van Wert, R., Gayer, G., Guo, H. H., Nair, V. S. 2016: -?

  View details for PubMedID 27512939

• Pre-treatment non-target lung FDG-PET uptake predicts symptomatic radiation pneumonitis following Stereotactic Ablative Radiotherapy (SABR). Radiotherapy and oncology Chaudhuri, A. A., Binkley, M. S., Rigdon, J., Carter, J. N., Aggarwal, S., Dudley, S. A., Qian, Y., Kumar, K. A., Hara, W. Y., Gensheimer, M., Nair, V. S., Maxim, P. G., Shultz, D. B., Bush, K., Trakul, N., Le, Q., Diehn, M., Loo, B. W., Guo, H. H. 2016; 119 (3): 454-460

  Abstract

  To determine if pre-treatment non-target lung FDG-PET uptake predicts for symptomatic radiation pneumonitis (RP) following lung stereotactic ablative radiotherapy (SABR).We reviewed a 258 patient database from our institution to identify 28 patients who experienced symptomatic (grade ⩾ 2) RP after SABR, and compared them to 57 controls who did not develop symptomatic RP. We compared clinical, dosimetric and functional imaging characteristics between the 2 cohorts including pre-treatment non-target lung FDG-PET uptake.Median follow-up time was 26.9 months. Patients who experienced symptomatic RP had significantly higher non-target lung FDG-PET uptake as measured by mean SUV (p < 0.0001) than controls. ROC analysis for symptomatic RP revealed area under the curve (AUC) of 0.74, with sensitivity 82.1% and specificity 57.9% with cutoff mean non-target lung SUV > 0.56. Predictive value increased (AUC of 0.82) when mean non-target lung SUV was combined with mean lung dose (MLD). We developed a 0-2 point model using these 2 variables, 1 point each for SUV > 0.56 or MLD > 5.88 Gy equivalent dose in 2 Gy per fraction (EQD2), predictive for symptomatic RP in our cohort with hazard ratio 10.01 for score 2 versus 0 (p < 0.001).Patients with elevated pre-SABR non-target lung FDG-PET uptake are at increased risk of symptomatic RP after lung SABR. Our predictive model suggests patients with mean non-target lung SUV > 0.56 and MLD > 5.88 Gy EQD2 are at highest risk. Our predictive model should be validated in an external cohort before clinical implementation.

  View details for DOI 10.1016/j.radonc.2016.05.007

  View details for PubMedID 27267049

• Methyl Methacrylate Mimicking a Retained Guide Wire. Journal of vascular and interventional radiology : JVIR Moradzadeh, N., Hwang, G., Nair, V., Guo, H. H. 2016; 27 (12): 1906

  View details for PubMedID 27886956

• Demonstration of peripheral nerve root involvement by non-Hodgkin's lymphoma on F-18-FDG PET/CT EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING Guo, H., Mosci, C., Iagaru, A. 2012; 39 (4): 729-730

  View details for DOI 10.1007/s00259-011-2000-0

  View details for Web of Science ID 000302287500024

  View details for PubMedID 22124779

• Frameshift Mutagenesis and Microsatellite Instability Induced by Human Alkyladenine DNA Glycosylase MOLECULAR CELL Klapacz, J., Lingaraju, G. M., Guo, H. H., Shah, D., Moar-Shoshani, A., Loeb, L. A., Samson, L. D. 2010; 37 (6): 843-853

  Abstract

  Human alkyladenine DNA glycosylase (hAAG) excises alkylated purines, hypoxanthine, and etheno bases from DNA to form abasic (AP) sites. Surprisingly, elevated expression of hAAG increases spontaneous frameshift mutagenesis. By random mutagenesis of eight active site residues, we isolated hAAG-Y127I/H136L double mutant that induces even higher rates of frameshift mutation than does the wild-type hAAG; the Y127I mutation accounts for the majority of the hAAG-Y127I/H136L-induced mutator phenotype. The hAAG-Y127I/H136L and hAAG-Y127I mutants increased the rate of spontaneous frameshifts by up to 120-fold in S. cerevisiae and also induced high rates of microsatellite instability (MSI) in human cells. hAAG and its mutants bind DNA containing one and two base-pair loops with significant affinity, thus shielding them from mismatch repair; the strength of such binding correlates with their ability to induce the mutator phenotype. This study provides important insights into the mechanism of hAAG-induced genomic instability.

  View details for DOI 10.1016/j.molcel.2010.01.038

  View details for Web of Science ID 000276135100011

  View details for PubMedID 20347426

  View details for PubMedCentralID PMC2894629

• Best Cases from the AFIP Fatal 2009 Influenza A (H1N1) Infection, Complicated by Acute Respiratory Distress Syndrome and Pulmonary Interstitial Emphysema RADIOGRAPHICS Guo, H. H., Sweeney, R. T., Regula, D., Leung, A. N. 2010; 30 (2): 327-333

  View details for DOI 10.1148/rg.302095213

  View details for Web of Science ID 000275622400003

  View details for PubMedID 20068001

• Substrate binding pocket residues of human alkyladenine-DNA glycosylase critical for methylating agent survival DNA REPAIR Chen, C., Guo, H. H., Shah, D., Blank, A., Samson, L. D., Loeb, L. A. 2008; 7 (10): 1731-1745

  Abstract

  Human alkyladenine-DNA glycosylase (AAG) initiates base excision repair (BER) of alkylated and deaminated bases in DNA. Here, we assessed the mutability of the AAG substrate binding pocket, and the essentiality of individual binding pocket amino acids for survival of methylation damage. We used oligonucleotide-directed mutagenesis to randomize 19 amino acids, 8 of which interact with substrate bases, and created more than 4.5 million variants. We expressed the mutant AAGs in repair-deficient Escherichia coli and selected for protection against the cytotoxicity of either methylmethane sulfonate (MMS) or methyl-lexitropsin (Me-lex), an agent that produces 3-methyladenine as the predominant base lesion. Sequence analysis of 116 methylation-resistant mutants revealed no substitutions for highly conserved Tyr(127)and His(136). In contrast, one mutation, L180F, was greatly enriched in both the MMS- and Me-lex-resistant libraries. Expression of the L180F single mutant conferred 4.4-fold enhanced survival at the high dose of MMS used for selection. The homogeneous L180F mutant enzyme exhibited 2.2-fold reduced excision of 3-methyladenine and 7.3-fold reduced excision of 7-methylguanine from methylated calf thymus DNA. Decreased excision of methylated bases by the mutant glycosylase could promote survival at high MMS concentrations, where the capacity of downstream enzymes to process toxic BER intermediates may be saturated. The mutant also displayed 6.6- and 3.0-fold reduced excision of 1,N(6)-ethenoadenine and hypoxanthine from oligonucleotide substrates, respectively, and a 1.7-fold increase in binding to abasic site-containing DNA. Our work provides in vivo evidence for the substrate binding mechanism deduced from crystal structures, illuminates the function of Leu(180) in wild-type human AAG, and is consistent with a role for balanced expression of BER enzymes in damage survival.

  View details for DOI 10.1016/j.dnarep.2008.06.019

  View details for Web of Science ID 000260621500012

  View details for PubMedID 18706524

• Protein tolerance to random amino acid change PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA GUO, H. H., Choe, J., Loeb, L. A. 2004; 101 (25): 9205-9210

  Abstract

  Mutagenesis of protein-encoding sequences occurs ubiquitously; it enables evolution, accumulates during aging, and is associated with disease. Many biotechnological methods exploit random mutations to evolve novel proteins. To quantitate protein tolerance to random change, it is vital to understand the probability that a random amino acid replacement will lead to a protein's functional inactivation. We define this probability as the "x factor." Here, we develop a broadly applicable approach to calculate x factors and demonstrate this method using the human DNA repair enzyme 3-methyladenine DNA glycosylase (AAG). Three gene-wide mutagenesis libraries were created, each with 10(5) diversity and averaging 2.2, 4.6, and 6.2 random amino acid changes per mutant. After determining the percentage of functional mutants in each library using high-stringency selection (>19,000-fold), the x factor was found to be 34% +/- 6%. Remarkably, reanalysis of data from studies of diverse proteins reveals similar inactivation probabilities. To delineate the nature of tolerated amino acid substitutions, we sequenced 244 surviving AAG mutants. The 920 tolerated substitutions were characterized by substitutability index and mapped onto the AAG primary, secondary, and known tertiary structures. Evolutionarily conserved residues show low substitutability indices. In AAG, beta strands are on average less substitutable than alpha helices; and surface loops that are not involved in DNA binding are the most substitutable. Our results are relevant to such diverse topics as applied molecular evolution, the rate of introduction of deleterious alleles into genomes in evolutionary history, and organisms' tolerance of mutational burden.

  View details for DOI 10.1073/pnas.0403255101

  View details for Web of Science ID 000222278600009

  View details for PubMedID 15197260

  View details for PubMedCentralID PMC438954

• Tumbling down a different pathway to genetic instability JOURNAL OF CLINICAL INVESTIGATION GUO, H. H., Loeb, L. A. 2003; 112 (12): 1793-1795

  Abstract

  Ulcerative colitis (UC), a chronic inflammatory condition associated with a predisposition to colon cancer, is frequently characterized by DNA damage in the form of microsatellite instability (MSI). A new report links inflammation in UC with increases in the DNA repair enzymes 3-methyladenine DNA glycosylase and apurinic/apyrimidinic endonuclease, and, paradoxically, with increased MSI. These findings may represent a novel mechanism contributing to MSI in chronic inflammation.

  View details for DOI 10.1172/JCI200320502

  View details for Web of Science ID 000187348300006

  View details for PubMedID 14679175

  View details for PubMedCentralID PMC297004

• Endogenous mutagenesis and cancer. Mutation research Davidson, J. F., Guo, H. H., Loeb, L. A. 2002; 509 (1-2): 17–21

  Abstract

  Mutations in DNA accrue relentlessly, largely via stochastic processes. Random changes accumulate, eventually disabling genetic components which result in the formation of the cancer phenotype. Given the infrequency of measured nucleotide changes and the requirement for several mutations to occur in the same cell, it has been postulated that the rate of mutation must become elevated early in the course of evolution of the cancer. Recently, large scale sequencing of tumor DNA has sought to directly measure random mutations. We discuss the implications of these findings and the factors that must be considered in order for fruitful determination of whether a mutator phenotype is a necessary precursor for cancer.

  View details for PubMedID 12427528