MR detection of degenerating uterine leiomyomas

Gonadotropin-releasing hormone (GnRH) analogues have been advocated for the conservative management of uterine leiomyoma. These drugs induce a hypoestrogenic state and affect undegenerated myoma cells. Therefore, we evaluated the usefulness of MRI for distinguishing undegenerated and degenerated leiomyomas.

Twenty lesions were studied in 16 patients with surgically resected leiomyoma. A 1.5 T unit was used to obtain T1- and T2-weighted images and Gd-DTPA-enhanced T1-weighted images. Signal intensity maps were made for each pulse sequence, and detailed histological maps were also made in the same plane as the MR images. Then the MR maps were compared with the histological maps of the resected specimens.

Interstitial edema, the initial sign of degeneration, was detected as a high signal intensity region on T2-weighted images and showed enhancement with Gd-DTPA. Hyaline degeneration could not be distinguished from smooth muscle whorls on T1- and T2-weighted images. However, undegenerated leiomyoma could be distinguished from hyaline degeneration, because the former was slightly enhanced by Gd-DTPA but the latter was not.

These findings showed that Gd-DTPA-enhanced MRI can distinguish undegenerated leiomyomas from degenerated leiomyomas and suggest that MRI may be useful for predicting the response of this tumor to GnRH analogue therapy.