[Magnetic resonance imaging in the diagnosis of prostatic carcinoma and benign hyperplasia]

Using a 0.5 tesla superconducting magnetic system, magnetic resonance imaging (MRI) studies were performed in 42 patients (27 prostatic carcinoma and 15 benign prostatic hyperplasia) and 2 healthy volunteers. Spin echo images were produced in the transverse, coronal and sagittal directions. T1 and T2 relaxation times were calculated from these images. The images of 2 normal prostates showed 2 separate zones: an internal zone and an external zone. The images of 8 of the 15 prostates with benign prostatic hyperplasia showed 3 zones: an internal zone, a band of low intensity and an external zone. Most of the cases of prostatic carcinoma showed extracapsular extension, so we could not detect zonal distinction of the images in 25 cases out of the 27 prostates with prostatic carcinoma. Most of the images of prostates with prostatic carcinoma showed irregular and asymmetric shape and inhomogeneous signal intensity. MRI had an accuracy of 85.7% in differentiating prostatic carcinoma from benign prostatic hyperplasia. A good correlation (r = 0.936) was observed between the weight of the whole prostate as predicted by MRI and the actual weight of the adenoma enucleated by retropubic prostatectomy. The change in volume of the prostate after hormone therapy was well evaluated by MRI. We were not able to differentiate prostatic carcinoma from benign prostatic hyperplasia on the basis of the T1 and T2 relaxation times alone. The serial measurements of the T1 and T2 relaxation times might be value in following therapeutic response of prostatic carcinoma.