Fig. 1.

Semi-automated pipeline to extract velocity from 4D flow cardiovascular magnetic resonance (4D flow CMR) contained solely within the pulmonary arteries through image segmentation and shape analysis algorithms as well as automated computation of velocity metrics from branches and cross-sectional slices throughout the cardiac cycle. Visualization of the 4D flow CMR-derived metrics extracted from the pulmonary arteries (PAs) show illustrative explanations of acceleration time ratio, fractional area of reverse flow, vorticity, helicity, and helical flow index. * = metric was computed from a mid-slice located 50% down the length of the vessel. ^† = metric was computed from a proximal slice located 10% down the length of the vessel. All other metrics were computed from the volumes of the main, left, and right PA branches