Shi Chen¹, Jaume Coll-Font^1,2,3, Robert Eder¹, Anna Foster ¹, Salva Yurista ^1,2,3, and Christopher T. Nguyen^1,2,3,4
1Cardiovascular Research Center, Massachusetts General Hospital, Charlestown, MA, United States, ²Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States, ³Harvard Medical School, Boston, MA, United States, ⁴Division of Health Science Technology, Harvard-Massachusetts Institute of Technology, Cambridge, MA, United States

Sexes and ages are known factors that contribute to cardiovascular pathophysiological variances and prognosis. This study used in-vivo cardiac diffusion tensor MRI (DT-MRI) to characterize how myocardial microstructure differs across sexes and ages. To that purpose, thirty healthy volunteers (14 female) were imaged with in-vivo cardiac DT-MRI and common DT-MRI parameters (MD, FA, HAT, E2A) were computed within the left ventricle (LV). No significant sex-related differences (11%, 9%, 3%, 9% respectively for MD, FA, HAT, E2A at septal regions) or age-related correlations were found. Taken together, sex and age had no effects on the quantification of in-vivo cardiac DT-MRI parameters.

Jaume Coll-Font^1,2,3, Shi Chen¹, Robert Eder¹, Yilin Fan⁴, Qiao Joyce Han¹, Maaike van den Boomen^1,2,3, David Sosnovik^1,2,3, Choukri Mekkaoui^2,3, and Christopher T. Nguyen^1,2,3
1Cardiology, Massachusetts General Hospital, Charlestown, MA, United States, ²Harvard Medical School, Boston, MA, United States, ³Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States, ⁴Massachusetts Insitute of Technology, Cambridge, MA, United States

For in-vivo cardiac diffusion-tensor MRI (DT-MRI), respiratory motion and B₀ field inhomogeneities produce misalignment and geometric distortion in diffusion weighted images acquired with conventional single shot echo planar imaging. We propose using Laplacian Eigenmaps (LE), a dimensionality reduction method, to retrospectively estimate the respiratory phase of DWI and facilitate both distortion correction (DisCo) and motion compensation (MoCo). LE-based DisCo and MoCo reduces geometric distortion by 13.2% while producing computationally efficient image alignment. Furthermore, preliminary results indicate the LE-based DisCo and MoCo can be applied with only acquiring a single set of b-value averages.

Kai Lin¹, Roberto Sarnari¹, Ashitha Pathrose¹, Daniel Gordon¹, Michael Markl¹, and James Carr^1
1Radiology, Northwestern University, Chicago, IL, United States

The existence of pulmonary hypertension (PH) can independently shorten the length of cardiac rest periods. The length of cardiac rest periods can be used to discriminate PH patients from healthy controls.

Mabel Shehada¹, Emile Shehada², Ramez Shehada³, and David Prutchi^4
1UCSD, San Diego, CA, United States, ²Yale University, New haven, CT, United States, ³Medical Technology Laboratories, La Mirada, CA, United States, ⁴Impulse Dynamics, MARLTON, NJ, United States

For implant systems composed of an implantable pulse generator (IPG) and lead(s), the MR-Conditional labeling specifies a magnetic spatial gradient for the whole system but not for its individual components. To identify the component experiencing the highest magnetic force, thus dictating the safe limit, we measured multiple IPGs and leads per ASTM F2052-15. The highest force on leads under 4.77T/m, 20T/m, and 50T/m was 0.003N, 0.021N, and 0.053N, respectively. The lowest IPG forces were 0.080N, 0.529N, and 1.322N. For any magnetic spatial gradient, the lowest IPG force was 2,480% greater than the highest lead force.

Michael Loecher^1,2 and Daniel B Ennis^1,2,3
1Radiology, Stanford University, Stanford, CA, United States, ²Radiology, Veterans Administration Health Care System, Palo Alto, CA, United States, ³Cardiovascular Institute, Stanford University, Stanford, CA, United States

We explored the application of acquiring Fourier Velocity Encoding (FVE) without spatial encoding to quickly estimate the velocity distribution within a volume of interest. One application is to allow for quick selection of Venc for a subsequent 4D-Flow acquisition, which can limit velocity aliasing and fine-tune the velocity-to-noise ratio for better data quality. Other applications may include new ways of looking at the pulsatility or turbulence of a volume of interest. In this work we implement a FVE sequence in Pulseq and run it in flow phantoms to demonstrate the proof-of-concept data of this technique.

Kelly Jarvis¹, Jackson E Moore¹, Maria Aristova¹, Ning Jin², Valerie Torres¹, Susanne Schnell^1,3, Eric Russell¹, Michael Markl¹, Emily Rogalski⁴, and Ann Ragin^1
1Radiology, Northwestern University, Chicago, IL, United States, ²Siemens Medical Solutions Inc., Cleveland, OH, United States, ³Medical Physics, University of Greifswald, Greifswald, Germany, ⁴Psychiatry and Behavioral Sciences, Northwestern University, Chicago, IL, United States

Mechanisms underlying heart-brain hemodynamic coupling and effects on the brain remain unclear due to challenges of measuring both heart and brain in a single MRI exam. We have developed a comprehensive MRI protocol that incorporates 1) 4D flow MRI of chest, 2) 4D flow MRI of head and 3) structural neuroimaging into one MRI exam to assess cardiovascular and cerebrovascular flow as well as white matter lesions and brain atrophy. This study demonstrates the utility of heart-brain MRI as viable new tool for in vivo evaluation of hemodynamic coupling along the entire heart-brain pathway.

Gaurav Sharma¹, Chai-Wan Kim^2,3, Xiaodong Wen¹, A. Dean Sherry^1,4,5, Chalermchai Khemtong^1,6,7, Craig R. Malloy^1,2,4, and Jay D. Horton^2,3
1Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, United States, ²Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, United States, ³Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX, United States, ⁴Department of Radiology, University of Texas Southwestern Medical Center, Dallas, TX, United States, ⁵Department of Chemistry, University of Texas at Dallas, Richardson, TX, United States, ⁶Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, University of Florida, Gainesville, FL, United States, ⁷Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, United States

The product of acetyl-CoA carboxylase (ACC), malonyl-CoA, inhibits oxidation of long chain fatty acids by mitochondria. Cardiac-specific deletion of ACC-2 is associated with increased oxidation of fatty acids, as expected, the effects on glucose oxidation are controversial, and increased oxidation of stored triglycerides has been postulated. Expression of the other isoform, ACC-1, is preserved in ACC-2 mutant hearts, so alternative sources of malonyl-CoA may be important.  We found that knock out of both isoforms was associated with a small increase in fatty acid oxidation, a small decrease in glucose oxidation, and little effect on oxidation of stored energy supplies. 

Gaurav Sharma¹, Ryan J. Vela², LaShondra Powell², Stanislaw Deja^3,4, Monika Mizerska³, Michael E. Jessen², Shawn C. Burgess^3,5, Craig R. Malloy^1,6,7, and Matthias Peltz^2
1Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, United States, ²Department of Cardiovascular and Thoracic Surgery, University of Texas Southwestern Medical Center, Dallas, TX, United States, ³Center for Human Nutrition, University of Texas Southwestern Medical Center, Dallas, TX, United States, ⁴Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, United States, ⁵Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX, United States, ⁶Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, United States, ⁷Department of Radiology, University of Texas Southwestern Medical Center, Dallas, TX, United States

Preservation of human hearts for transplantation is important to optimize outcomes.  Standard ischemic cooling methods are intended to preserve high energy phosphates but risk tissue damage due to freezing; an alternative with precise temperature control has emerged as an option. The efficacy of this technique in preserving high energy phosphates and other metabolites has not been examined. We compared conventional cold storage to a commercial device with precise temperature control for preservation of human hearts not suitable for transplant.  There were no significant differences in high energy phosphates or other metabolites using precise temperature control compared to conventional cold storage.

El-Sayed H Ibrahim¹, Jason Jarzembowski¹, and Suresh Kumar^1
1Medical College of Wisconsin, Milwaukee, WI, United States

Healthy heart is a metabolically dynamic organ requiring large energy resource, and fatty acid oxidation (FAO) pathway predominantly supports this energy demands. Disorders of FAO pathways could range from mild and manageable to severe and life-threatening. In this study, we use MRI to evaluate the heart function in mitochondrial trifunctional protein (MTP) mutant rats, where clinical symptoms of this disorder overlap with other less severe FAO deficiencies and are often misdiagnosed. The results showed that MRI strain imaging revealed subclinical cardiac dysfunction in the MTP mutant rats with the degree of strain reduction depending on strain direction and regional location. 

Jackson E. Moore¹, Kristina M. Zvolanek¹, Maria Aristova¹, Ramez Abdalla¹, Ann Ragin¹, Eric Russell¹, Fan Caprio², Sameer A. Ansari¹, Susanne Schnell^1,3, and Michael Markl^1
1Radiology, Northwestern University, Chicago, IL, United States, ²Neurology, Northwestern University, Chicago, IL, United States, ³Institute of Physics, University of Greifswald, Greifswald, Germany

Cerebrovascular dual-venc 4D Flow MRI has utility in evaluating intracranial hemodynamics - benefitting from full circle of Willis (CoW) volumetric coverage, time-resolved, three-directional velocity encoding, and velocity dynamic range. Analysis of hemodynamic measures was completed using a comprehensive, semi-automated vessel identification and segmentation workflow for 10 subjects who underwent two scans within 30 days. Test-retest analysis of cerebrovascular dual-venc 4D Flow MRI and measures of CoW 3D flow dynamics demonstrated excellent repeatability for flow and peak velocity measures and lower reproducibility for pulsatility and resistive indices. Future work may include a larger cohort or more advanced analysis of velocity-derived parameters.