0217: Is high temporal resolution achievable for pediatric cardiac acquisitions during several heart beats? Illustration with cardiac phase contrast cine-MRI

Abstract

During pediatric cardiac Cine-MRI, data acquired during cycles of different lengths must be combined. Feinstein’s model is used to project multiple cardiac cycles of variable lengths into a mean cycle. 1/The temporal errors during Feinstein’s projection were computed in 306 cardiac cycles fully characterized by tissue Doppler imaging with 6-phase analysis (from a population of 7 children and young adults). 2/The effects of these temporal errors on tissue velocities were assessed by simulating a typical tissue phase mapping acquisition and reconstruction. 3/Myocardial velocities curves, extracted from high-resolution phase-contrast cine images, were compared for the 6 volunteers with lowest and highest heart rate variability, within a population of 36young adults. 1/The mean of temporal misalignments was 30ms over the cardiac cycle but reached 60ms during early diastole. 2/During phase contrast MRI simulation, early diastole velocity peaks were diminished by 5cm/s leading to virtual disappearance of isovolumic relaxation peaks. 3/The smoothing and erasing of isovolumic relaxation peaks was confirmed on tissue phase mapping velocity curves, between subjects with low and high heart rate variability (p=0.05). Feinstein cardiac model creates temporal misalignments that impair high temporal resolution (notably for phase contrast cine imaging) in a population of high heart rate variations such as in paediatry (figure next page). Abstract 0217 – Figure: Velocity curves with/without heart rate variation