Using 5D flow MRI to decode the effects of rhythm on left atrial 3D flow dynamics in patients with atrial fibrillation
Liliana Ma, Jérôme Yerly, Lorenzo Di Sopra, Davide Piccini, Jeesoo Lee, Amanda DiCarlo, Rod Passman, Philip Greenland, Daniel Kim, Matthias Stuber, Michael Markl
Abstract
Purpose
This study used a 5D flow framework to explore the influence of arrhythmia on thrombogenic hemodynamic parameters in patients with atrial fibrillation (AF).
Methods
A fully self‐gated, 3D radial, highly accelerated free‐running 5D flow sequence with interleaved four‐point velocity‐encoding was acquired using an in vitro arrhythmic flow phantom and in 25 patients with a history of AF (68 ± 8 y, 6 female). Self‐gating signals were used to calculate AF burden, bin data, and tag each k‐space line with its RRLength. Data were binned as an RR‐resolved dataset with four RR‐interval bins (RR1‐RR4, short‐to‐long) for compressed sensing reconstruction. AF burden was calculated as interquartile range of all intrascan RR‐intervals divided by median RR‐interval, and left atrial (LA) stasis as the percent of the cardiac cycle where the velocity was <0.1 m/s.
Results
In vitro results demonstrated successful recovery of RR‐binned flow curves using RR‐resolved 5D flow compared to a real‐time PC reference standard. In vivo, 5D flow was acquired in 8:48 minutes. AF burden was significantly correlated with 5D flow‐derived peak (PV) and mean (MV) velocity and stasis (|ρ| = 0.54‐0.75, P < .001). Sensitivity analyses determined a threshold for low versus high AF burden at 9.7%. High burden patients had increased LA mean stasis (up to +42%, P < .01), and lower MV and PV (−30%, −40.6%, respectively, P < .01). RR4 deviated furthest from respiratory‐resolved reconstruction (end‐expiration) with increased mean stasis (7.6% ± 14.0%, P = .10) and decreased PV (−12.7 ± 14.2%, P = .09).
Conclusions
RR‐resolved 5D flow can capture temporal and RR‐resolved 3D hemodynamics in <10 minutes and offers a novel approach to investigate arrhythmias.