Respiratory-gating Reduces Motion Artifacts Due to Uterine Displacement in T2-weighted MR Imaging of the Female Pelvis.

PURPOSE: This study aimed to assess the potential enhancement of image quality in fast-spin-echo T2-weighted images (FSE-T2WI) with respiratory-gating compared to conventional FSE-T2WI and to clarify how abdominal wall motion affects uterine displacement and consequently impacts image quality.

METHODS

One hundred and three women who underwent pelvic MRI using a 3T-MRI scanner were enrolled. FSE-T2WI with and without respiratory-gating was visually assessed for motion-related artifacts, and the image quality was categorized as poor, moderate, or excellent. The uterus was classified as type 1 (on the bladder), type 2 (not on the bladder and not retroflexed), or type 3 (uterus contacting the vertebrae or a retroflexed uterus). The relationships (1) between the abdominal wall and uterine displacements, (2) between the quality of FSE-T2WI with and without respiratory-gating and uterine displacement, and (3) between uterine displacement and types were investigated.

RESULTS

Respiratory-gated FSE-T2WI achieved better overall image quality, with poor, moderate, and excellent ratings observed in 27, 44, and 32 patients, respectively, compared with 53, 34, and 16 patients for conventional FSE-T2WI. Improvement with respiratory-gating was observed in 43 patients, particularly in those with type 1 and type 2 uteri, whereas only 8 patients showed decreased image quality. A strong correlation was found between abdominal wall and uterine displacements (P < 0.001), indicating that uterine motion is largely driven by respiration. The amplitude of uterine displacement was significantly smaller in type 3 uteri (P < 0.05), consistent with fewer motion-related artifacts.

CONCLUSION

Respiratory-gated FSE-T2WI effectively reduces motion artifacts caused by respiratory-induced uterine displacement, particularly in type 1 and type 2 uteri where displacement is pronounced.