Publications

2018
Hossam El-Rewaidy, Maryam Nezafat, Jihye Jang, Shiro Nakamori, Ahmed Fahmy, and Reza Nezafat. 2018. “Nonrigid Active Shape Model-Based Registration Framework for Motion Correction of Cardiac T1 Mapping.” Magn Reson Med.Abstract

PURPOSE: Accurate reconstruction of myocardial T1 maps from a series of T1-weighted images consists of cardiac motions induced from breathing and diaphragmatic drifts. We propose and evaluate a new framework based on active shape models to correct for motion in myocardial T1 maps.
METHODS: Multiple appearance models were built at different inversion time intervals to model the blood-myocardium contrast and brightness changes during the longitudinal relaxation. Myocardial inner and outer borders were automatically segmented using the built models, and the extracted contours were used to register the T1-weighted images. Data acquired from 210 patients using a free-breathing acquisition protocol were used to train and evaluate the proposed framework. Two independent readers evaluated the quality of the T1 maps before and after correction using a four-point score. The mean absolute distance and Dice index were used to validate the registration process.
RESULTS: The testing data set from 180 patients at 5 short axial slices showed a significant decrease of mean absolute distance (from 3.3 ± 1.6 to 2.3 ± 0.8 mm, P < 0.001) and increase of Dice (from 0.89 ± 0.08 to 0.94 ± 0.4%, P < 0.001) before and after correction, respectively. The T1 map quality improved in 70 ± 0.3% of the motion-affected maps after correction. Motion-corrupted segments of the myocardium reduced from 21.8 to 8.5% (P < 0.001) after correction.
CONCLUSION: The proposed method for nonrigid registration of T1-weighted images allows T1 measurements in more myocardial segments by reducing motion-induced T1 estimation errors in myocardial segments. Magn Reson Med, 2018. © 2018 International Society for Magnetic Resonance in Medicine.

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2017
El-Rewaidy H, Nakamori S, Addae G, Manning W, and Nezafat R. 2017. “Active shape models based motion correction for myocardial T1 Mapping.” Proceedings of the 25th Annual Meeting of ISMRM Hawaii USA.
Fahmy AS, Basha TA, and Nezafat R. 2017. “Analytically-derived parameter scouting for dark-blood Late Gadolinium Enhancement (DB-LGE) imaging.” Proceedings of the 25th Annual Meeting of ISMRM Hawaii USA.
Nakamori S, Alakbarli J, Addae G, Jang J, Berg S, Kissinger KV, Goddu B, Manning WJ, and Nezafat R. 2017. “Changes in myocardial native T1 and T2 after physical exercise: A feasibility study.” 20th Annual Scientific Sessions Society for Cardiovascular Magnetic Resonance Washington DC USA.
Whitaker J, Tschabrunn C, Jang J, Leshem E, Neill O M, Kissinger K, V, Manning W, J, Anter J, and Nezafat R. 2017. “Characterization of left ventricular injury and remodelling using serial CMR scans in a swine model of myocardial infarction with ventricular arrhythmia.” 20th Annual Scientific Sessions Society for Cardiovascular Magnetic Resonance Washington DC USA.
Kang J, Jang J, Tarokh V, and Nezafat R. 2017. “Dictionary-based reconstruction for free-breathing myocardial T1 mapping.” 25th Annual Meeting of ISMRM Hawaii USA.
Rausch J, Bjoern Menze B, Chang R, Jang J, Applebaum E, and Nezafat R. 2017. “Fully automated left ventricle scar quantification with deep learning.” Proceedings of the 25th Annual Meeting of ISMRM Hawaii USA.
Whitaker J, Tschabrunn C, Anter E, Manning W, J, and Nezafat R. 2017. “Identification of right ventricular infarction using dark-blood late gadolinium enhanced LGE-CMR in a swine ischemia-reperfusion model.” 20th Annual Scientific Sessions Society for Cardiovascular Magnetic Resonance Washington DC USA.
Nakamori S, Ismail H, Ngo LH, Buxton AE, Manning WJ, and Nezafat R. 2017. “Impact of left ventricular geometry in predicting ventricular tachyarrhythmia in Patients with Left Ventricular Dysfunction: A Comprehensive Cardiovascular Magnetic Resonance Study .” 20th Annual Scientific Sessions Society for Cardiovascular Magnetic Resonance Washington DC USA.
Jang J, Nakamori S, and Nezafat R. 2017. “Improving precision of myocardial T1 mapping with 3-parameter model using tissue characteristic-based denoising.” Proceedings of the 25th Annual Meeting of ISMRM Hawaii USA.
Nakamori S, Alakbarli J, Bellm S, Motiwala SR, Addae G, Manning WJ, and Nezafat R. 2017. “Native T1 value in the remote myocardium is independently associated with left ventricular dysfunction in patients with prior myocardial infarction.” 20th Annual Scientific Sessions Society for Cardiovascular Magnetic Resonance Washington DC USA.
Jang J, Whitaker J, Tschabrunn CM, Leshem E, Contreras-Valdes FM, Anter E, and Nezafat R. 2017. “Optimal cut-off for unipolar and bipolar voltages to predict scar in LGE-MRI in swine model of ventricular tachycardia with Prior Myocardial Infarction.” Heart Rhythm 2017 Chicago Illinois.
Jang J, Contreras-Valdes FM, Tschabrunn CM, Leshem E, Whitaker J, Buxton AE, Nezafat R., and Anter E. 2017. “Substrate mapping of VT using decremental pacing: A novel strategy to identify localized regions susceptible for reentry.” Heart Rhythm 2017 Chicago Illinois.
Jang J, Addae G, Manning W, and Nezafat R. 2017. “Three-dimensional holographic visualization of high-resolution myocardial scar on HoloLens.” Proceedings of the 25th Annual Meeting of ISMRM Hawaii USA.
Tamer A Basha, Mehmet Akçakaya, Charlene Liew, Connie W Tsao, Francesca N Delling, Gifty Addae, Long Ngo, Warren J Manning, and Reza Nezafat. 2017. “Clinical performance of high-resolution late gadolinium enhancement imaging with compressed sensing.” J Magn Reson Imaging, 46, 6, Pp. 1829-1838.Abstract
PURPOSE: To evaluate diagnostic image quality of 3D late gadolinium enhancement (LGE) with high isotropic spatial resolution (∼1.4 mm(3) ) images reconstructed from randomly undersampled k-space using LOw-dimensional-structure Self-learning and Thresholding (LOST). MATERIALS AND METHODS: We prospectively enrolled 270 patients (181 men; 55 ± 14 years) referred for myocardial viability assessment. 3D LGE with isotropic spatial resolution of 1.4 ± 0.1 mm(3) was acquired at 1.5T using a LOST acceleration rate of 3 to 5. In a subset of 121 patients, 3D LGE or phase-sensitive LGE were acquired with parallel imaging with an acceleration rate of 2 for comparison. Two readers evaluated image quality using a scale of 1 (poor) to 4 (excellent) and assessed for scar presence. The McNemar test statistic was used to compare the proportion of detected scar between the two sequences. We assessed the association between image quality and characteristics (age, gender, torso dimension, weight, heart rate), using generalized linear models. RESULTS: Overall, LGE detection proportions for 3D LGE with LOST were similar between readers 1 and 2 (16.30% vs. 18.15%). For image quality, readers gave 85.9% and 80.0%, respectively, for images categorized as good or excellent. Overall proportion of scar presence was not statistically different from conventional 3D LGE (28% vs. 33% [P = 0.17] for reader 1 and 26% vs. 31% [P = 0.37] for reader 2). Increasing subject heart rate was associated with lower image quality (estimated slope = -0.009 (P = 0.001)). CONCLUSION: High-resolution 3D LGE with LOST yields good to excellent image quality in >80% of patients and identifies patients with LV scar at the same rate as conventional 3D LGE. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2017;46:1829-1838.
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Daniel R Messroghli, James C Moon, Vanessa M Ferreira, Lars Grosse-Wortmann, Taigang He, Peter Kellman, Julia Mascherbauer, Reza Nezafat, Michael Salerno, Erik B Schelbert, Andrew J Taylor, Richard Thompson, Martin Ugander, Ruud B van Heeswijk, and Matthias G Friedrich. 2017. “Clinical recommendations for cardiovascular magnetic resonance mapping of T1, T2, T2* and extracellular volume: A consensus statement by the Society for Cardiovascular Magnetic Resonance (SCMR) endorsed by the European Association for Cardiovascular Imagi.” J Cardiovasc Magn Reson, 19, 1, Pp. 75.Abstract
Parametric mapping techniques provide a non-invasive tool for quantifying tissue alterations in myocardial disease in those eligible for cardiovascular magnetic resonance (CMR). Parametric mapping with CMR now permits the routine spatial visualization and quantification of changes in myocardial composition based on changes in T1, T2, and T2*(star) relaxation times and extracellular volume (ECV). These changes include specific disease pathways related to mainly intracellular disturbances of the cardiomyocyte (e.g., iron overload, or glycosphingolipid accumulation in Anderson-Fabry disease); extracellular disturbances in the myocardial interstitium (e.g., myocardial fibrosis or cardiac amyloidosis from accumulation of collagen or amyloid proteins, respectively); or both (myocardial edema with increased intracellular and/or extracellular water). Parametric mapping promises improvements in patient care through advances in quantitative diagnostics, inter- and intra-patient comparability, and relatedly improvements in treatment. There is a multitude of technical approaches and potential applications. This document provides a summary of the existing evidence for the clinical value of parametric mapping in the heart as of mid 2017, and gives recommendations for practical use in different clinical scenarios for scientists, clinicians, and CMR manufacturers.
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An H Bui, Sébastien Roujol, Murilo Foppa, Kraig V Kissinger, Beth Goddu, Thomas H Hauser, Peter J Zimetbaum, Long H Ngo, Warren J Manning, Reza Nezafat, and Francesca N Delling. 2017. “Diffuse myocardial fibrosis in patients with mitral valve prolapse and ventricular arrhythmia.” Heart, 103, 3, Pp. 204-209.Abstract
OBJECTIVE: We aimed to investigate the association of diffuse myocardial fibrosis by cardiac magnetic resonance (CMR) T1 with complex ventricular arrhythmia (ComVA) in mitral valve prolapse (MVP). METHODS: A retrospective analysis was performed on 41 consecutive patients with MVP referred for CMR between 2006 and 2011, and 31 healthy controls. Arrhythmia analysis was available in 23 patients with MVP with Holter/event monitors. Left ventricular (LV) septal T1 times were derived from Look-Locker sequences after administration of 0.2 mmol/kg gadopentetate dimeglumine. Late gadolinium enhancement (LGE) CMR images were available for all subjects. RESULTS: Patients with MVP had significantly shorter postcontrast T1 times when compared with controls (334±52 vs 363±58 ms; p=0.03) despite similar LV ejection fraction (LVEF) (63±7 vs 60±6%, p=0.10). In a multivariable analysis, LV end-diastolic volume, LVEF and mitral regurgitation fraction were all correlates of T1 times, with LVEF and LV end-diastolic volume being the strongest (p=0.005, p=0.008 and p=0.045, respectively; model adjusted R(2)=0.30). Patients with MVP with ComVA had significantly shorter postcontrast T1 times when compared with patients with MVP without ComVA (324 (296, 348) vs 354 (327, 376) ms; p=0.03) and only 5/14 (36%) had evidence of papillary muscle LGE. CONCLUSIONS: MVP may be associated with diffuse LV myocardial fibrosis as suggested by reduced postcontrast T1 times. Diffuse interstitial derangement is linked to subclinical systolic dysfunction, and may contribute to ComVA in MVP-related mitral regurgitation, even in the absence of focal fibrosis.
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Tamer A Basha, Maxine C Tang, Connie Tsao, Cory M Tschabrunn, Elad Anter, Warren J Manning, and Reza Nezafat. 2017. “Improved dark blood late gadolinium enhancement (DB-LGE) imaging using an optimized joint inversion preparation and T2 magnetization preparation.” Magn Reson Med.Abstract
PURPOSE: To develop a dark blood-late gadolinium enhancement (DB-LGE) sequence that improves scar-blood contrast and delineation of scar region. METHODS: The DB-LGE sequence uses an inversion pulse followed by T2 magnetization preparation to suppress blood and normal myocardium. Time delays inserted after preparation pulses and T2 -magnetization-prep duration are used to adjust tissue contrast. Selection of these parameters was optimized using numerical simulations and phantom experiments. We evaluated DB-LGE in 9 swine and 42 patients (56 ± 14 years, 33 male). Improvement in scar-blood contrast and overall image quality was subjectively evaluated by two independent readers (1 = poor, 4 = excellent). The signal ratios among scar, blood, and myocardium were compared. RESULTS: Simulations and phantom studies demonstrated that simultaneous nulling of myocardium and blood can be achieved by selecting appropriate timing parameters. The scar-blood contrast score was significantly higher for DB-LGE (P < 0.001) with no significant difference in overall image quality (P > 0.05). Scar-blood signal ratios for DB-LGE versus LGE were 5.0 ± 2.8 versus 1.5 ± 0.5 (P < 0.001) for patients, and 2.2 ± 0.7 versus 1.0 ± 0.4 (P = 0.0023) for animals. Scar-myocardium signal ratios were 5.7 ± 2.9 versus 6.3 ± 2.6 (P = 0.35) for patients, and 3.7 ± 1.1 versus 4.1 ± 2.0 (P = 0.60) for swine. CONCLUSIONS: The DB-LGE sequence simultaneously reduces normal myocardium and blood signal intensity, thereby enhancing scar-blood contrast while preserving scar-myocardium contrast. Magn Reson Med, 2017. © 2017 International Society for Magnetic Resonance in Medicine.
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Shiro Nakamori, An H Bui, Jihye Jang, Hossam A El-Rewaidy, Shingo Kato, Long H Ngo, Mark E Josephson, Warren J Manning, and Reza Nezafat. 2017. “Increased myocardial native T1 relaxation time in patients with nonischemic dilated cardiomyopathy with complex ventricular arrhythmia.” J Magn Reson Imaging.Abstract
PURPOSE: To study the relationship between diffuse myocardial fibrosis and complex ventricular arrhythmias (ComVA) in patients with nonischemic dilated cardiomyopathy (NICM). We hypothesized that NICM patients with ComVA would have a higher native myocardial T1 time, suggesting more extensive myocardial diffuse fibrosis. MATERIALS AND METHODS: We prospectively enrolled NICM patients with a history of ComVA (n = 50) and age-matched NICM patients without ComVA (n = 57). Imaging was performed at 1.5T with a protocol that included cine magnetic resonance imaging (MRI) for left ventricular (LV) function, late gadolinium enhancement (LGE) for focal scar, and native T1 mapping for diffuse fibrosis assessment. RESULTS: Global native T1 time was significantly higher in patients with NICM with ComVA when compared to patients with NICM without ComVA (1131 ± 42 vs. 1107 ± 45 msec, P = 0.006), and this finding remained after excluding segments with scar on LGE (1124 ± 36 vs. 1102 ± 44 msec, P = 0.006). Native T1 was similar in NICM patients with and without the presence of LGE (1121 ± 39 vs. 1117 ± 48 msec, P = 0.68) and mildly correlated with LV end-diastolic volume index (r = 0.27, P = 0.005), LV end-systolic volume index (r = 0.24, P = 0.01), and LV ejection fraction (r = -0.28, P = 0.003). Native T1 value for each 10-msec increment was an independent predictor of ComVA (odds ratio 1.14, 95% confidence interval 1.03-1.25; P = 0.008) beyond LV function and LGE. CONCLUSION: NICM patients with ComVA have higher native T1 compared to NICM without any documented ComVA. Native myocardial T1 is independently associated with ComVA, after adjusting for LV function and LGE. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2017. In memoriam: The authors are grateful for Dr. Josephson's inspiring guidance and contributions to this study.
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Alex Y Tan, Bruce D Nearing, Michael Rosenberg, Reza Nezafat, Mark E Josephson, and Richard L Verrier. 2017. “Interlead heterogeneity of R- and T-wave morphology in standard 12-lead ECGs predicts sustained ventricular tachycardia/fibrillation and arrhythmic death in patients with cardiomyopathy.” J Cardiovasc Electrophysiol, 28, 11, Pp. 1324-1333.Abstract
INTRODUCTION: Nonuniformities in depolarization and repolarization morphology are critical factors in ventricular arrhythmogenesis. METHODS AND RESULTS: We assessed interlead R-wave heterogeneity (RWH) and T-wave heterogeneity (TWH) in standard 12-lead electrocardiograms (ECGs) using second central moment analysis. This technique quantifies variance about the mean morphology of beats in adjoining precordial leads, V4 , V5 , and V6 in this study. The study was conducted in 120 consecutive patients without an apparent reversible trigger for ventricular tachycardia (VT), recent myocardial infarction, or active ischemia, who presented for electrophysiologic study, implantable cardioverter defibrillator (ICD) placement, or generator change at our institution from 2008 to 2011. Primary outcome was sustained VT/ventricular fibrillation (VF) or appropriate ICD therapies. Secondary outcome was arrhythmic death or resuscitated cardiac arrest. Cutpoints for elevated RWH (>160 μV) and TWH (>80 μV) identified 67% of primary outcome cases and 85% of secondary outcome cases. Cardiomyopathy patients who met the primary outcome (n = 42) had significantly higher TWH than those who did not (n = 28) (TWH: 95 ± 11 μV vs. 44 ± 9 μV, P < 0.002). Likewise, cardiomyopathy patients who met secondary outcome (N = 13) had VT/VF during follow-up and also had significantly higher TWH than survivors (N = 57) (TWH: 105 ± 24 μV vs. 67 ± 8 μV, P < 0.002). Kaplan-Meier analysis revealed significant differences in arrhythmia-free survival (P = 0.012) and total survival (P = 0.011) among cardiomyopathy patients with (n = 37) compared to without (n = 33) elevated RWH and/or TWH independent of age, sex, and left ventricular ejection fraction (LVEF). CONCLUSION: Interlead RWH and TWH in 12-lead ECGs predict sustained ventricular arrhythmia, appropriate ICD therapies, and arrhythmic death or cardiac arrest in cardiomyopathy patients independent of LVEF and other standard variables.
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