Comparison of MRI and sonography in the preliminary evaluation for fibroid embolization

The purpose of our study was to evaluate whether pelvic MRI provides additional clinically relevant information after sonography in the preprocedure evaluation of uterine artery embolization of fibroids.

Forty-nine women who presented for consultation for uterine artery embolization were retrospectively reviewed. The MRI and sonography scans were independently evaluated and compared for uterine size, fibroid size and location (categorized as paraendometrial, intramural, subserosal, or pedunculated) of the four largest fibroids in each patient, and the total number of fibroids present.

One hundred twenty-two fibroids were measured. The uterine volume was significantly smaller as measured on MRI compared with sonography (p = 0.01). We found good MRI and sonography correlation of the volume of the single largest fibroid in each patient (R = 0.87) but poor correlation of fibroid location (R = 0.17). MRI detected 31 paraendometrial fibroids and three pedunculated fibroids that were thought to be intramural fibroids on sonography. Five fibroids thought to be paraendometrial on sonography were confirmed to be subserosal or intramural on MRI. Discrepancy in the total number of fibroids was noted, with additional fibroids found on MRI in 31 of 49 patients and erroneously suspected on sonography in five of 49 patients. Pelvic MRI affected management in 11 of 49 patients, leading to cancellation of uterine artery embolization in four patients. In another seven patients who were originally thought to be poor candidates on the basis of sonographic findings, uterine artery embolization was performed. MRI did not alter the management plan in 38 patients.

MRI provided considerable additional information compared with sonography and affected clinical decision making in a substantial number of patients. MRI should be considered in all patients being evaluated for uterine artery embolization.