Creating Healthy Age-Sex-matched Left Ventricular Velocity Atlases and Extracting Energy-based Hemodynamics Using...

This study proposes a method to create a 4D-flow magnetic resonance imaging (4D-flow MRI) based left ventricular (LV) velocity atlas and extract hemodynamic parameters at the peak-systolic phase. Twenty-seven healthy controls without any cardiac disease (44% female) underwent a consistent standardized imaging protocol using 3T/MRI scanners. Phase-contrast MR angiography and an average heart were created. Contour-based segmentation was done for 30 phases covering the entire LV. For each age-and-sex-matched group (female/male and 20-40/41-61 years), an averaged 3D velocity field and a shared geometry were created by maximizing the overlap of all LVs non-rigidly utilizing affine registration. Normal velocity atlases were created by interpolating the absolute velocities (m/s) to the voxels of the shared geometry and averaged over all cases in the respective groups. Later, viscous energy dissipation and kinetic energy (VED, KE, mJ) were quantified. The average mean squared loss and dice coefficient were 14.45±3.1% and 0.84. VED^Mean and KE^Mean were reduced among the older cases (Female: KE=5.26±5.9 vs. 3.3±3.68, VED=0.19±1.94 vs. 0.05±0.3; Male: KE=4.58±4.21 vs. 2.09±2.41, VED=0.07±0.42 vs. 0.03±0.26; mJ). Older males exhibited a lower Velocity^Mean than older females and younger males (t=2.62, 2.52; p=0.02, 0.02; 23.81%, 38.46%; respectively). They also showed 36.67% lower KE^Mean than older females (t=2.37, p=0.05). Age was negatively correlated to KE (Females: r=-0.723, p=0.008; Males: r=-0.536, p=0.04), VED (Females: r=-0.786, p=0.002; Males: r=-0.748, p=0.001), and velocity (Females: r=-0.722, p=0.008; Males: r=-0.771, p<0.001). This study demonstrates the feasibility of velocity atlases for extracting a range of age-and-sex-matched energetics and highlights altered hemodynamics associated with aging.Clinical Relevance- This study demonstrates the utility of 4D-flow MRI-based velocity atlases for age-and-sex-matched hemodynamic assessment, offering a novel tool for identifying pathological conditions and refining cardiovascular diagnosis.