Magnetic Resonance Signal Intensity Ratio Measurement Before Uterine Artery Embolization: Ability to Predict Fibroid Size Reduction

PURPOSE: To evaluate whether the magnetic resonance imaging (MRI) signal intensity (SI) ratio between the dominant fibroid and the periphery striated muscle can predict fibroid volume reduction >50% after uterine fibroid embolization (UFE).

MATERIALS AND METHODS: From October 2013 until May 2016, 52 patients were included in this prospective study. The SI ratio before UFE was calculated using circular region of interests placed on the dominant fibroid and the iliac muscle. The SI fibroid-to-iliac muscle ratio was calculated as SI of the dominant fibroid/SI of the iliac muscle on T1-, T2-, and T1 post-contrast-weighted sequences. The dominant fibroid volume was measured and analyzed before and after UFE.

RESULTS: In all, 46 patients who completed the three-month follow-up MRI were available for analysis. The correlation between SI fibroid-to-muscle ratio at the T2-weighted sequence and imaging volume reduction outcome was statistically significant (p < 0.002). All other parameters showed no statistically significant reduction in fibroid volume: (p < 0.68) for SI ratio at T1-weighted, (p < 0.13) for SI ratio at T1 post-contrast, and (p < 0.58) for fibroid volume. Spearman's rank showed positive correlation (r = 0.439, p < 0.003) between the fibroid-to-muscle SI ratio on T2-weighted sequence. The area under curve (AUC) for SI fibroid-to-muscle ratio on T2-weighted sequence was 0.776. For the other parameters, the AUC values were 0.512, 0.671, and 0.578, respectively.

CONCLUSION: SI dominant fibroid-to-muscle ratio at T2-weighted sequence before UFE was significantly related to dominant fibroid volume reduction after UFE and may be used for better patient selection.