5 T vs 3 T Non-contrast enhanced MRA: enhanced vessel delineation and lipid suppression in lower limbs

This study compared image quality and lipid suppression efficacy between 5 and 3 T MR systems for lower-extremity non-contrast enhanced magnetic resonance angiography (NCE-MRA) using an optimized 2D time-of-flight (TOF) sequence with spatially separated lipid pre-saturation (SLIP).

Ten healthy volunteers underwent 2D TOF examination on lower limbs at both field strengths. The SLIP technique was evaluated across field strengths and compared with conventional CHESS to assess lipid suppression efficiency. Subjective scoring was used to assess vessel visualization and image quality, while quantitative analysis of vessel-to-muscle contrast ratios was performed. Statistical significance was determined using paired t-tests. Three patients with Peripheral Arterial Occlusive Disease (PAOD) were evaluated at 5 T and compared to computed tomography angiography (CTA) as the reference standard.

The implementation of SLIP underscores the capability of increased field strength for more effective implementation of chemical shift-based lipid suppression technique. 5 T NCE MRA demonstrated higher Likert scores of radiologists' subjective evaluations of vessel delineation (5 T vs 3 T: 3.73 vs. 3.47, P < 0.001) and image quality (3.58 vs 3.27, P = 0.002) than 3 T. Vessel-to-background ratio (VBR) (14.87 ± 3.80 vs 10.07 ± 2.64, P < 0.001) and vessel contrast-to-background ratio (VCBR) were higher at 5 T (0.84 ± 0.11 vs 0.77 ± 0.12, P < 0 .001), indicating enhanced vessel delineation than 3 T.

5 T NCE-MRA outperforms 3 T in visualizing lower limb vasculature, with enhanced lipid suppression and reduced in-plane saturation artifacts, offering a non-invasive alternative for peripheral vascular assessment.