Comparison of 1.5 T and 3 T non-contrast-enhanced MR angiography for visualization of uterine and ovarian arteries before uterine artery embolization

Abstract

Objectives: This study aimed to compare the performance of non-contrast-enhanced magnetic resonance angiography (NCE-MRA) at 1.5 T and 3 T for the visualization of uterine and ovarian arteries (OAs) before uterine artery embolization (UAE).

Methods: Preprocedural pelvic NCE-MRA images of 85 symptomatic patients undergoing UAE for the treatment of uterine leiomyomas were reviewed by two specialists in pelvic MRI. Left and right uterine arteries (UAs) were judged separately and scored on a 5-point scale. Score 5 was the highest, in which the UA could be visualized inside the musculature, forming a peritumoral plexus. Score 1 was the lowest, where visualization was limited to the descending segment. The detection of enlarged OAs was also compared. The Mann-Whitney U and Fisher exact tests were used for statistical analysis. p < 0.05 was considered to be statistically significant.

Results: Of the 170 UAs, 110 were classified at 1.5 T and 60 were classified at 3 T. Median (interquartile range [IQR]) score was 3 (IQR: 2-4) for visualization at 1.5 T vs 5 (IQR: 4-5) for 3 T. The scores for UA visualization were significantly higher at 3 T (p < 0.05). For enlarged OAs, NCE-MRA at 1.5 T and 3 T visualized 7 and 5 enlarged OAs, respectively; there was no significant difference between the two field strengths (p = 0.36).

Conclusions: NCE-MRA performed at 3 T can visualize UAs over a greater range than at 1.5 T. No difference was found regarding the detection of enlarged OAs.

Key points: • Preprocedural MRA can provide interventional radiologists with valuable information, including the origin and course of the uterine arteries and the existence of collateral feeders to the tumor. • This study demonstrates the superiority of non-contrast-enhanced MRA performed at 3 T over that performed at 1.5 T in the visualization of the uterine arteries in patients undergoing uterine artery embolization for the treatment of uterine leiomyomas. • Non-contrast-enhanced MRA is a useful imaging modality for patients with symptomatic leiomyoma undergoing uterine artery embolization in whom contrast administration is unfeasible. If available, it is preferable to perform the examination with a 3 T MR unit rather than a 1.5 T MR unit.

Keywords: Leiomyoma; Magnetic resonance angiography; Ovarian artery; Uterine artery; Uterine artery embolization.