4D flow MRI andT1-Mapping: Assessment of altered cardiac hemodynamics and extracellular volume fraction in hypertrophic cardiomyopathy

Pim van Ooij, Bradley D. Allen, Carla Contaldi, Julio Garcia, Jeremy Collins, James Carr, Lubna Choudhury, Robert O. Bonow, Alex J. Barker, Michael Markl
2015 Journal of Magnetic Resonance Imaging  
Purpose-Hypertrophic cardiomyopathy (HCM) is associated with altered hemodynamics in the left ventricular out flow tract (LVOT) and myocardial tissue abnormalities such as fibrosis. The aim of this study was to quantify changes in LVOT 3D hemodynamics and myocardial extracellular volume fraction (ECV, measure of fibrosis) and to investigate relationships between elevated flow metrics and left ventricular (LV) tissue abnormalities. Methods and Results-Cardiac MRI including 4D flow (field
more » ... =1.5T, resolution=2.1-4.0×2.1-4.0×2.5-3.2mm 3 ; venc=150-250cm/s; TE/TR/FA=2.2-2.5ms/4.6-4.9ms/15°) for the invivo assessment of 3D blood flow velocities with full coverage of the LVOT was applied in 35 patients with HCM (54±15 years) and 10 age matched healthy controls (45±14 years). In addition, pre-and post-contrast myocardial T1-mapping (resolution=2.3×1.8mm, slice thickness=8mm, TE/TR-FA=1.0-1.1ms/2.0-2.2ms/35°) of the LV (basal, mid-ventricular, apical short axis) was performed in a subgroup of 23 HCM patients. Analysis included the segmentation of the LVOT and quantification of peak systolic LVOT pressure gradients and rate of viscous energy loss as well as left ventricular ECV. Results-HCM patients demonstrated significantly elevated peak systolic LVOT pressure gradients (21±16mmHg vs. 9±2mmHg) and energy loss (3.8±2.5mW vs. 1.5±0.7mW, P<0.005) compared to controls. There was a significant relationship between increased LV fibrosis (ECV) with both elevated pressure gradients (R 2 =0.44, P<0.001) and energy loss (R 2 =0.46, P<0.001). Conclusions-The integration of 4D-flow and T 1 -mapping-MRI allowed for the evaluation of tissue and flow abnormalities in HCM patients. Our findings suggest a mechanistic link between abnormal LVOT flow, increased LV loading, and adverse myocardial remodeling in HCM. Data Analysis -SAM and LVOT Dimensions End-diastolic septal thickness, end-diastolic septum/free wall ratio and presence of SAM were evaluated and quantified on 3-chamber CINE images. End-diastolic LVOT diameter van Ooij et al.
doi:10.1002/jmri.24962 pmid:26227419 pmcid:PMC4850842 fatcat:ucgz5bn3yfatnh5z7h3cqtcexm