The value of detection of flow voids between the uterus and the leiomyoma with MRI.

Flow voids are occasionally seen between the uterus and the leiomyoma. This study was performed to determine the prevalence of this sign and its relation to tumor size and location, internal signal intensity of the leiomyomas, and the ease of detectability using different MR sequences. Also, to understand the pathologic causes for the phenomenon of flow voids. The MR images of the pelvis in 92 females with 359 uterine leiomyomas were analyzed. Flow voids located between the uterus and the leiomyomas were seen in 32 lesions on T1-weighted images and in 12 on T2-weighted images. Flow void was seen exclusively in leiomyomas of 3-cm diameter or larger. In five pedunculated subserous leiomyomas, flow voids were seen within the pedicle of the tumor. Large leiomyomas and leiomyomas with irregular signal intensity on T2-weighted images showed significantly greater frequency of signal void than other leiomyomas (P < .01). The sign was not seen in any other pelvic tumors. On pathologic evaluation, the flow voids were found to correspond to dilated feeding arteries located outside the capsule of the leiomyoma.