Prediction of early response to uterine artery embolization in fibroids: Value of MR signal intensity ratio

ObjectiveTo quantitatively assess magnetic resonance (MR) imaging findings that help predict early post-therapeutic response in fibroids following uterine artery embolization (UAE).MethodsFifteen patients with a total of 52 fibroids underwent UAE. The signal intensity ratio (SIR) on T1-, T2-, diffusion weighted and gadolinium-enhanced images was calculated by dividing the mean signal intensity of fibroids by that of the abdominal rectus muscle. Fibroids were divided into the two groups: affected (post-UAE volume reduction rate > median of all fibroids) and unaffected (< median rate). The SIRs were compared between the two groups. ROC analysis was used to evaluate the predictive performance for differentiating the affected from unaffected lesions.ResultsThe SIRs of the affected group were significantly lower on T1-weighted images (0.85 ± 0.1 vs 0.95 ± 0.2) (P = 0.0001), but higher on T2-weighted (1.30 ± 0.6 vs 1.12 ± 0.9) (P = 0.026) and gadolinium-enhanced images (1.51 ± 0.2 vs 1.20 ± 0.4) (P = 0.0002) than those of the unaffected group. There was no significant difference in ADC values between the two groups (P = 0.510). The sensitivity, specificity, and area under the ROC curve (AUC) in the prediction of the affected lesions were 92%, 50%, and 0.712 with SIR on T1-weighted images, and 85%, 62%, and 0.731 with SIR on gadolinium-enhanced images, respectively.ConclusionsThe SIRs on T1-weighted images and gadolinium-enhanced images were useful for the prediction of the changes in size of fibroids responding to UAE.