Person: Sosnovik, David
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Sosnovik
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David
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Sosnovik, David
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Publication In vivo fiber tractography of the right and left ventricles using diffusion tensor MRI of the entire human heart(BioMed Central, 2014) Mekkaoui, Choukri; Reese, Timothy; Jackowski, Marcel P; Bhat, Himanshu; Kostis, William J; Sosnovik, DavidPublication Correlation of DTI tractography with electroanatomic mapping in normal and infarcted myocardium(BioMed Central, 2014) Mekkaoui, Choukri; Jackowski, Marcel P; Thiagalingam, Aravinda; Kostis, William J; Nielles-Vallespin, Sonia; Firmin, David; Bhat, Himanshu; Ruskin, Jeremy; Reese, Timothy; Sosnovik, DavidPublication Diffusion MRI Tractography of the Developing Human Fetal Heart(Public Library of Science, 2013) Mekkaoui, Choukri; Porayette, Prashob; Jackowski, Marcel P.; Kostis, William J; Dai, Guangping; Sanders, Stephen; Sosnovik, DavidObjective: Human myocardium has a complex and anisotropic 3D fiber pattern. It remains unknown, however, when in fetal life this anisotropic pattern develops and whether the human heart is structurally fully mature at birth. We aimed here to use diffusion tensor MRI (DTI) tractography to characterize the evolution of fiber architecture in the developing human fetal heart. Methods: Human fetal hearts (n = 5) between 10–19 weeks of gestation were studied. The heart from a 6-day old neonate and an adult human heart served as controls. The degree of myocardial anisotropy was measured by calculating the fractional anisotropy (FA) index. In addition, fiber tracts were created by numerically integrating the primary eigenvector field in the heart into coherent streamlines. Results: At 10–14 weeks the fetal hearts were highly isotropic and few tracts could be resolved. Between 14–19 weeks the anisotropy seen in the adult heart began to develop. Coherent fiber tracts were well resolved by 19 weeks. The 19-week myocardium, however, remained weakly anisotropic with a low FA and no discernable sheet structure. Conclusions: The human fetal heart remains highly isotropic until 14–19 weeks, at which time cardiomyocytes self-align into coherent tracts. This process lags 2–3 months behind the onset of cardiac contraction, which may be a prerequisite for cardiomyocyte maturation and alignment. No evidence of a connective tissue scaffold guiding this process could be identified by DTI. Maturation of the heart’s sheet structure occurs late in gestation and evolves further after birth.Publication Theranostic Nucleic Acid Binding Nanoprobe Exerts Anti-inflammatory and Cytoprotective Effects in Ischemic Injury(Ivyspring International Publisher, 2017) Chen, Howard; Yuan, Hushan; Cho, Hoonsung; Feng, Yan; Ngoy, Soeun; Kumar, Anand; Liao, Ronglih; Chao, Wei; Josephson, Lee; Sosnovik, DavidExtracellular nucleic acids are proinflammatory molecules that have been implicated in a diverse range of diseases. We report here the development of a multivalent nucleic acid scavenging nanoprobe, where the fluorochrome thiazole orange (TO) is conjugated to a polymeric 40 kDa dextran carrier. Dextran-TO (Dex-TO) has nanomolar affinity for mammalian and bacterial nucleic acids and attenuates the production of inflammatory cytokines from activated macrophages exposed to DNA and RNA. Mice with myocardial ischemia reperfusion that were treated with Dex-TO showed a decrease in myocardial macrophage infiltration at 24 hours (p<0.05) and a decrease in infarct size (18% ± 9%, p<0.01) on day 7. Dex-TO allows sites of injury to be identified with fluorescence imaging, while simultaneously exerting an anti-inflammatory and cytoprotective effect. Dex-TO could be of significant diagnostic and therapeutic (theranostic) utility in a broad range of conditions including ischemia, trauma, burns, sepsis and autoimmune disease.Publication Dual-Phase Cardiac Diffusion Tensor Imaging with Strain Correction(Public Library of Science, 2014) Stoeck, Christian T.; Kalinowska, Aleksandra; von Deuster, Constantin; Harmer, Jack; Chan, Rachel W.; Niemann, Markus; Manka, Robert; Atkinson, David; Sosnovik, David; Mekkaoui, Choukri; Kozerke, SebastianPurpose In this work we present a dual-phase diffusion tensor imaging (DTI) technique that incorporates a correction scheme for the cardiac material strain, based on 3D myocardial tagging. Methods: In vivo dual-phase cardiac DTI with a stimulated echo approach and 3D tagging was performed in 10 healthy volunteers. The time course of material strain was estimated from the tagging data and used to correct for strain effects in the diffusion weighted acquisition. Mean diffusivity, fractional anisotropy, helix, transverse and sheet angles were calculated and compared between systole and diastole, with and without strain correction. Data acquired at the systolic sweet spot, where the effects of strain are eliminated, served as a reference. Results: The impact of strain correction on helix angle was small. However, large differences were observed in the transverse and sheet angle values, with and without strain correction. The standard deviation of systolic transverse angles was significantly reduced from 35.9±3.9° to 27.8°±3.5° (p<0.001) upon strain-correction indicating more coherent fiber tracks after correction. Myocyte aggregate structure was aligned more longitudinally in systole compared to diastole as reflected by an increased transmural range of helix angles (71.8°±3.9° systole vs. 55.6°±5.6°, p<0.001 diastole). While diastolic sheet angle histograms had dominant counts at high sheet angle values, systolic histograms showed lower sheet angle values indicating a reorientation of myocyte sheets during contraction. Conclusion: An approach for dual-phase cardiac DTI with correction for material strain has been successfully implemented. This technique allows assessing dynamic changes in myofiber architecture between systole and diastole, and emphasizes the need for strain correction when sheet architecture in the heart is imaged with a stimulated echo approach.Publication Functional brown adipose tissue limits cardiomyocyte injury and adverse remodeling in catecholamine-induced cardiomyopathy(Elsevier BV, 2015) Thoonen, Robrecht; Ernande, Laura; Cheng, Juan; Nagasaka, Yasuko; Yao, Vincent; Miranda-Bezerra, Alexandre; Chen, Chan; Chao, Wei; Panagia, Marcello; Sosnovik, David; Puppala, Dheeraj; Armoundas, Antonis; Hindle, Allyson; Bloch, Kenneth; Buys, Emmanuel; Scherrer-Crosbie, MarielleBrown adipose tissue (BAT) has well recognized thermogenic properties mediated by uncoupling protein 1 (UCP1); more recently, BAT has been demonstrated to modulate cardiovascular risk factors. To investigate whether BAT also affects myocardial injury and remodeling, UCP1-deficient (UCP1−/−) mice, which have dysfunctional BAT, were subjected to catecholamine-induced cardiomyopathy. At baseline, there were no differences in echocardiographic parameters, plasma cardiac troponin I (cTnI) or myocardial fibrosis between wild-type (WT) and UCP1−/− mice. Isoproterenol infusion increased cTnI and myocardial fibrosis and induced left ventricular (LV) hypertrophy in both WT and UCP1−/− mice. UCP1−/− mice also demonstrated exaggerated myocardial injury, fibrosis, and adverse remodeling, as well as decreased survival. Transplantation of WT BAT to UCP1−/− mice prevented the isoproterenol-induced cTnI increase and improved survival, whereas UCP1−/− BAT transplanted to either UCP1−/− or WT mice had no effect on cTnI release. After 3 days of isoproterenol treatment, phosphorylated AKT and ERK were lower in the LV's of UCP1−/− mice than in those of WT mice. Activation of BAT was also noted in a model of chronic ischemic cardiomyopathy, and was correlated to LV dysfunction. Deficiency in UCP1, and accompanying BAT dysfunction, increases cardiomyocyte injury and adverse LV remodeling, and decreases survival in a mouse model of catecholamine-induced cardiomyopathy. Myocardial injury and decreased survival are rescued by transplantation of functional BAT to UCP1−/− mice, suggesting a systemic cardioprotective role of functional BAT. BAT is also activated in chronic ischemic cardiomyopathy.Publication Differential response of the left and right ventricles to pressure overload revealed with diffusion tensor MRI tractography of the heart in vivo(BioMed Central, 2015) Mekkaoui, Choukri; Chen, Iris Y; Chen, Howard; Kostis, William J; Pereira, Fabricio; Jackowski, Marcel P; Sosnovik, DavidPublication Infarct delineation in patients with acute myocardial infarction using the tractographic propagation angle and late gadolinium enhancement(BioMed Central, 2015) Mekkaoui, Choukri; Jackowski, Marcel P; Stoeck, Christian T; Kostis, William J; Pereira, Fabricio; Kozerke, Sebastian; Sosnovik, DavidPublication Seeing What We Build—The Need for New Imaging Techniques in Myocardial Regeneration(John Wiley & Sons, Ltd, 2015) Sosnovik, DavidPublication Diffusion MRI in the heart(John Wiley and Sons Inc., 2015) Mekkaoui, Choukri; Reese, Timothy; Jackowski, Marcel P.; Bhat, Himanshu; Sosnovik, DavidDiffusion MRI provides unique information on the structure, organization, and integrity of the myocardium without the need for exogenous contrast agents. Diffusion MRI in the heart, however, has proven technically challenging because of the intrinsic non‐rigid deformation during the cardiac cycle, displacement of the myocardium due to respiratory motion, signal inhomogeneity within the thorax, and short transverse relaxation times. Recently developed accelerated diffusion‐weighted MR acquisition sequences combined with advanced post‐processing techniques have improved the accuracy and efficiency of diffusion MRI in the myocardium. In this review, we describe the solutions and approaches that have been developed to enable diffusion MRI of the heart in vivo, including a dual‐gated stimulated echo approach, a velocity‐ (M 1) or an acceleration‐ (M 2) compensated pulsed gradient spin echo approach, and the use of principal component analysis filtering. The structure of the myocardium and the application of these techniques in ischemic heart disease are also briefly reviewed. The advent of clinical MR systems with stronger gradients will likely facilitate the translation of cardiac diffusion MRI into clinical use. The addition of diffusion MRI to the well‐established set of cardiovascular imaging techniques should lead to new and complementary approaches for the diagnosis and evaluation of patients with heart disease. © 2015 The Authors. NMR in Biomedicine published by John Wiley & Sons Ltd.
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