Cysts of the prostate and seminal vesicles: MR imaging findings in 11 cases.

Cysts of the prostate and seminal vesicles are confusing abnormalities because they are uncommon and their origin is uncertain. Several approaches to diagnosis have been used, most recently CT and transrectal sonography. In this study, we investigated the value of MR imaging in the diagnosis of six cases of prostatic cyst and five cases of cysts of the seminal vesicles. All patients were symptomatic. T1- and T2-weighted spin-echo images were obtained in all cases; pathologic confirmation was available in four patients. MR images were analyzed prospectively without knowledge of clinical data or the results of other imaging procedures. In all cases, low- and high-signal masses were observed on T1- and T2-weighted images, respectively. The cysts were unilocular with a sharply defined margin, ranging from 0.5 to 3.0 cm in diameter. The thin wall was of low signal intensity on T2-weighted images. Our experience suggests that MR imaging is useful in demonstrating the liquid content of prostatic and seminal-vesicle cysts and in establishing their size and location.