Dynamic whole-heart MRI of congenital heart disease patients in the presence of turbulent flow

BACKGROUND: Ferumoxytol-enhanced dynamic whole-heart MRI is a promising technique for imaging patients with congenital heart disease (CHD). However, lesions that cause flow turbulence can result in artifacts that obscure the images and affect their diagnostic quality. The goal of this work is to develop and test an approach for dynamic whole-heart MRI in CHD patients with preserved image quality in the presence of turbulent flow. METHODS: A 3D radial ultra-short echo time (UTE) acquisition was integrated within the free-running framework for cardiac and respiratory motion-resolved (5D) whole-heart MRI. We prospectively validated our approach in a cohort of 21 CHD patients (age 11.9±9.2 years; 14 male) between July 2021 and February 2023. We compared UTE images to a previously established gradient recalled echo (GRE) approach. Quantitative (contrast, sharpness) and qualitative (expert grading) comparisons of images were performed. The severity of flow artifacts was also quantitatively (signal loss) and qualitatively (expert grading) compared. Statistical significance was tested using the paired t-test or the Wilcoxon signed rank test. RESULTS: UTE and GRE images were not significantly different in terms of sharpness (0.54±0.10 versus 0.57±0.12, p=.09), and image quality grading (OBS1: 2.5 [1] versus 2.5 [1], p =.10; OBS2: 3 [0.75] versus 3 [1.5], p=.74; OBS3: 4 [0] versus 4 [0], p =.5). Blood-to-myocardium contrast was significantly higher in UTE images (4.92±0.79 versus 3.89±0.37) while blood-to-fat contrast was significantly lower (1.74±0.42 versus 2.03±0.54). UTE images had significantly fewer flow artifacts than GRE images as attested by both signal loss (8.1% [3.2] versus 47.4% [17.6]) and flow artifact grade (OBS1:0 [1] versus 2 [1]; OBS2: 0[0] versus 1 [2]; OBS3: 0 [0] versus 1 [1.25]). Prominent systolic flow artifacts in GRE images were absent in the corresponding UTE images, even at locations of lesions with a propensity for flow turbulences. CONCLUSION: Free-running 3D radial UTE imaging enabled the acquisition of dynamic whole-heart images with consistent visualization of cardiovascular structures throughout the cardiac cycle despite the presence of flow turbulences.