Anatomy and pathology of the male pelvis by magnetic resonance imaging.

Magnetic resonance imaging (MRI) of the male pelvis was performed in 25 subjects: five normal volunteers; six patients with carcinoma of the bladder; nine with benign nodular hyperplasia (including five with concomitant bladder carcinoma); nine with prostatic carcinoma; and one with a lymphocele after radical prostatectomy. The display of normal anatomy is enhanced by the ability of the MRI device to provide images in direct transverse, sagittal, and coronal planes. Sessile and pedunculated types of bladder carcinoma are readily shown due to the superior ability of MRI for soft-tissue characterization. Direct sagittal scans are advantageous for evaluation of tumors at the bladder base, and by combining two different planes of images, the extent of the neoplasm is better delineated. In the analysis of the prostate, MRI displays the gland in three dimensions and therefore allows accurate volumetric measurements. The greatest potential of MRI seems to be its ability to detect pathology confined to the gland. However, it is not yet known if a neoplastic nodule can be differentiated from chronic prostatitis. Unlike x-ray CT, metallic clips produce no streaking artifacts, giving MRI a definite advantage in the evaluation of patients after radical surgery. These observations were made on a small number of patients. If the results are confirmed with a larger number of patients, MRI will assume a prominent role in the clinical evaluation of bladder and prostate cancer.