Exploring the limits of scan time reduction for ferumoxytol-enhanced whole-heart angiography in congenital heart disease patients.

Abstract

Introduction: One of the major challenges in CMR is to abbreviate scan times to create shorter protocols that are compatible with clinical workflows. In 3D magnetic resonance angiography (MRA), several strategies have been proposed to shorten scan times, relying on ECG-triggering or self-navigation for motion management. However, these methods are susceptible to heart rate variabilities or respiratory drifts. A similarity-driven multi-dimensional binning algorithm (SIMBA) was introduced to obtain 3D whole-heart angiography from ferumoxytol-enhanced free-running MRI data by extracting distinct motion states. This study explores the limits of acceleration of free-running MRI by leveraging the increase in signal from ferumoxytol by using SIMBA, and its compressed sensing extension XD-MC-SIMBA, while preserving image quality.

Methods: Data from 6-minute free-running acquisitions of 30 congenital heart disease (CHD) patients were retrospectively undersampled to simulate datasets of 5-, 4-, 3-, 2-, and 1-minute acquisition times. Data-driven SIMBA and XD-MC-SIMBA reconstructions were applied to all datasets. The consistency of the data selection was assessed, and image quality was analyzed by computing different sharpness metrics as a function of undersampling. Image quality was scored using a 5-point Likert scale. Additionally, shorter 3-minute acquisitions were prospectively acquired in nine CHD patients.

Results: The motion states selected with SIMBA were consistent across all levels of undersampling, with only 2 out of 30 cases showing completely different data selections. Image quality metrics decreased with increased undersampling, with lower values in SIMBA compared to XD-MC-SIMBA. On average, the diagnostic quality scores were good, with lower scores for 2-minute and 1-minute datasets. Using XD-MC-SIMBA, the quality scores were higher in 43% of cases compared to SIMBA. Moreover 58% of the 1-minute datasets improved to good or excellent quality thanks to XD-MC-SIMBA. All three 3-minute acquisitions were scored as having excellent diagnostic quality.

Conclusions: This study demonstrates that ferumoxytol-enhanced free-running MRI can be highly accelerated for 3D angiography in CHD patients when combined with a data-driven SIMBA reconstruction. With the aid of compressed sensing, XD-MC-SIMBA supports the acceleration down to 3minutes or less.