Person: Nezafat, Reza
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Nezafat
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Reza
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Nezafat, Reza
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Publication Correction to: 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 Imaging (EACVI)(BioMed Central, 2018) Messroghli, Daniel R.; Moon, James C.; Ferreira, Vanessa M.; Grosse-Wortmann, Lars; He, Taigang; Kellman, Peter; Mascherbauer, Julia; Nezafat, Reza; Salerno, Michael; Schelbert, Erik B.; Taylor, Andrew J.; Thompson, Richard B.; Ugander, Martin; van Heeswijk, Ruud B.; Friedrich, Matthias G.Publication Left Atrial Epicardial Fat Volume Is Associated With Atrial Fibrillation: A Prospective Cardiovascular Magnetic Resonance 3D Dixon Study(John Wiley and Sons Inc., 2018) Nakamori, Shiro; Nezafat, Maryam; Ngo, Long; Manning, Warren; Nezafat, RezaBackground: Recent studies demonstrated a strong association between atrial fibrillation (AF) and epicardial fat around the left atrium (LA). We sought to assess whether epicardial fat volume around the LA is associated with AF, and to determine the additive value of LA‐epicardial fat measurements to LA structural remodeling for identifying patients with AF using 3‐dimensional multi‐echo Dixon fat–water separated cardiovascular magnetic resonance. Methods and Results: A total of 105 subjects were studied: 53 patients with a history of AF and 52 age‐matched patients with other cardiovascular diseases but no history of AF. The 3‐dimensional multi‐echo Dixon fat‐water separated sequence was performed for LA‐epicardial fat measurements. AF patients had significantly greater LA‐epicardial fat (28.9±12.3 and 14.2±7.3 mL for AF and non‐AF, respectively; P<0.001) and LA volume (110.8±38.2 and 89.7±30.3 mL for AF and non‐AF, respectively; P=0.002). LA‐epicardial fat adjusted for LA volume was still higher in patients with AF compared with those without AF (P<0.001). LA‐epicardial fat and hypertension were independently associated with the risk of AF (odds ratio, 1.17; 95% confidence interval, 1.10%–1.25%, P<0.001, and odds ratio, 3.29; 95% confidence interval, 1.17%–9.27%, P=0.03, respectively). In multivariable logistic regression analysis adjusted for body surface area, LA‐epicardial fat remained significant and an increase per mL was associated with a 42% increase in the odds of AF presence (odds ratio, 1.42; 95% confidence interval, 1.23%–1.62%, P<0.001). Combined assessment of LA‐epicardial fat and LA volume provided greater discriminatory performance for detecting AF than LA volume alone (c‐statistic=0.88 and 0.74, respectively, DeLong test; P<0.001). Conclusions: Cardiovascular magnetic resonance 3‐dimensional Dixon‐based LA‐epicardial fat volume is significantly increased in AF patients. LA‐epicardial fat measured by 3‐dimensional Dixon provides greater performance for detecting AF beyond LA structural remodeling.Publication Highly conductive, stretchable and biocompatible Ag–Au core–sheath nanowire composite for wearable and implantable bioelectronics(Springer Science and Business Media LLC, 2018-08-13) Choi, Suji; Han, Sang Ihn; Jung, Dongjun; Hwang, Hye Jin; Lim, Chaehong; Bae, Soochan; Park, Ok Kyu; Tschabrunn, Cory M.; Lee, Mincheol; Bae, Sun Youn; Yu, Ji Woong; Ryu, Ji Ho; Lee, Sang-Woo; Park, Kyungpyo; Kang, Peter; Lee, Won Bo; Nezafat, Reza; Hyeon, Taeghwan; Kim, Dae-HyeongWearable and implantable devices require conductive, stretchable and biocompatible materials. However, obtaining composites that simultaneously fulfil these requirements is challenging due to a trade-off between conductivity and stretchability. Here, we report on Ag-Au nanocomposites composed of ultralong gold-coated silver nanowires in an elastomeric block-copolymer matrix. Owing to the high aspect ratio and percolation network of the Ag-Au nanowires, the nanocomposites exhibit an optimized conductivity of 41,850 S cm-1 (maximum of 72,600 S cm-1). Phase separation in the Ag-Au nanocomposite during the solvent-drying process generates a microstructure that yields an optimized stretchability of 266% (maximum of 840%). The thick gold sheath deposited on the silver nanowire surface prevents oxidation and silver ion leaching, making the composite biocompatible and highly conductive. Using the nanocomposite, we successfully fabricate wearable and implantable soft bioelectronic devices that can be conformally integrated with human skin and swine heart for continuous electrophysiological recording, and electrical and thermal stimulation.Publication 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 Imaging (EACVI)(BioMed Central, 2017) Messroghli, Daniel R.; Moon, James C.; Ferreira, Vanessa M.; Grosse-Wortmann, Lars; He, Taigang; Kellman, Peter; Mascherbauer, Julia; Nezafat, Reza; Salerno, Michael; Schelbert, Erik B.; Taylor, Andrew J.; Thompson, Richard; Ugander, Martin; van Heeswijk, Ruud B.; Friedrich, Matthias G.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.Publication Gray blood late gadolinium enhancement cardiovascular magnetic resonance for improved detection of myocardial scar(BioMed Central, 2018) Fahmy, Ahmed S.; Neisius, Ulf; Tsao, Connie; Berg, Sophie; Goddu, Elizabeth; Pierce, Patrick; Basha, Tamer A.; Ngo, Long; Manning, Warren; Nezafat, RezaBackground: Low scar-to-blood contrast in late gadolinium enhanced (LGE) MRI limits the visualization of scars adjacent to the blood pool. Nulling the blood signal improves scar detection but results in lack of contrast between myocardium and blood, which makes clinical evaluation of LGE images more difficult. Methods: GB-LGE contrast is achieved through partial suppression of the blood signal using T2 magnetization preparation between the inversion pulse and acquisition. The timing parameters of GB-LGE sequence are determined by optimizing a cost-function representing the desired tissue contrast. The proposed 3D GB-LGE sequence was evaluated using phantoms, human subjects (n = 45) and a swine model of myocardial infarction (n = 5). Two independent readers subjectively evaluated the image quality and ability to identify and localize scarring in GB-LGE compared to black-blood LGE (BB-LGE) (i.e., with complete blood nulling) and conventional (bright-blood) LGE. Results: GB-LGE contrast was successfully generated in phantoms and all in-vivo scans. The scar-to-blood contrast was improved in GB-LGE compared to conventional LGE in humans (1.1 ± 0.5 vs. 0.6 ± 0.4, P < 0.001) and in animals (1.5 ± 0.2 vs. -0.03 ± 0.2). In patients, GB-LGE detected more tissue scarring compared to BB-LGE and conventional LGE. The subjective scores of the GB-LGE ability for localizing LV scar and detecting papillary scar were improved as compared with both BB-LGE (P < 0.024) and conventional LGE (P < 0.001). In the swine infarction model, GB-LGE scores for the ability to localize LV scar scores were consistently higher than those of both BB-LGE and conventional-LGE. Conclusion: GB-LGE imaging improves the ability to identify and localize myocardial scarring compared to both BB-LGE and conventional LGE. Further studies are warranted to histologically validate GB-LGE. Electronic supplementary material The online version of this article (10.1186/s12968-018-0442-2) contains supplementary material, which is available to authorized users.Publication Efficient calculation of g-factors for CG-SENSE in high dimensions: noise amplification in random undersampling(BioMed Central, 2014) Akcakaya, Mehmet; Basha, Tamer A; Manning, Warren; Nezafat, RezaPublication Improved motion correction for T1 mapping(BioMed Central, 2014) Roujol, Sébastien; Foppa, Murilo; Kawaji, Keigo; Kissinger, Kraig V; Goddu, Beth; Manning, Warren; Nezafat, RezaPublication Accuracy and reproducibility of four T1 mapping sequences: a head-to-head comparison of MOLLI, ShMOLLI, SASHA, and SAPPHIRE(BioMed Central, 2014) Roujol, Sébastien; Weingartner, Sebastian; Foppa, Murilo; Chow, Kelvin; Kawaji, Keigo; Kissinger, Kraig V; Goddu, Beth; Berg, Sophie; Kellman, Peter; Manning, Warren; Thompson, Richard B; Nezafat, RezaPublication Selection of sampling points for saturation recovery based myocardial T1 mapping(BioMed Central, 2014) Akcakaya, Mehmet; Weingartner, Sebastian; Manning, Warren; Nezafat, RezaPublication Characterization of Respiratory and Cardiac Motion from Electro-Anatomical Mapping Data for Improved Fusion of MRI to Left Ventricular Electrograms(Public Library of Science, 2013) Roujol, Sébastien; Anter, Elad; Josephson, Mark; Nezafat, RezaAccurate fusion of late gadolinium enhancement magnetic resonance imaging (MRI) and electro-anatomical voltage mapping (EAM) is required to evaluate the potential of MRI to identify the substrate of ventricular tachycardia. However, both datasets are not acquired at the same cardiac phase and EAM data is corrupted with respiratory motion limiting the accuracy of current rigid fusion techniques. Knowledge of cardiac and respiratory motion during EAM is thus required to enhance the fusion process. In this study, we propose a novel approach to characterize both cardiac and respiratory motion from EAM data using the temporal evolution of the 3D catheter location recorded from clinical EAM systems. Cardiac and respiratory motion components are extracted from the recorded catheter location using multi-band filters. Filters are calibrated for each EAM point using estimates of heart rate and respiratory rate. The method was first evaluated in numerical simulations using 3D models of cardiac and respiratory motions of the heart generated from real time MRI data acquired in 5 healthy subjects. An accuracy of 0.6–0.7 mm was found for both cardiac and respiratory motion estimates in numerical simulations. Cardiac and respiratory motions were then characterized in 27 patients who underwent LV mapping for treatment of ventricular tachycardia. Mean maximum amplitude of cardiac and respiratory motion was 10.2±2.7 mm (min = 5.5, max = 16.9) and 8.8±2.3 mm (min = 4.3, max = 14.8), respectively. 3D Cardiac and respiratory motions could be estimated from the recorded catheter location and the method does not rely on additional imaging modality such as X-ray fluoroscopy and can be used in conventional electrophysiology laboratory setting.