Noninvasive left ventricular pressure-volume loops based on combined 4D flow MRI and CFD

Abstract

A novel approach to generate left ventricular (LV) pressure-volume (PV) loops from combined 4D Flow MRI and computational fluid dynamics (CFD) is presented. Pressure was calculated from person-specific three-dimensional (3D) CFD models created from LV segmentations and peak-systolic pressure from the one-dimensional 111-artery CFD model, with aortic flow from 4D Flow MRI as input. Ten healthy volunteers underwent scan-rescan MRI. Additionally, one patient without cardiovascular abnormalities underwent MRI and invasive catheter measurement for single-case comparison. Scan-rescan reproducibility was very good overall, with no significant differences in any parameters and ICCs of all parameters but minimum pressure were significant and high (0.55-0.99). Aortic flow of 3D CFD model correlated well with 4D Flow (ICC = 0.74) and stroke volume of LV segmentation (ICC = 0.90). Segmentation volume variability resulted in 12% difference in stroke work and mean external power, while aortic flow variability resulted in 10-11% difference in most parameters. Single-case comparison is promising, with only 1.8 mmHg and 0.005 mmHg/mL difference in minimum pressure and EDPVR, and <10% differences for other parameters. Noninvasive pressure-volume loops can therefore reproducibly be generated from only aortic flow, cine short axis MRI, and brachial pressure measurement. Single-case comparison shows promise, but larger validation studies are needed.