Magnetic resonance imaging in the evaluation of prostate cancer

Advantages of magnetic resonance imaging (MRI) in the study of prostatic disease include a precise anatomical display in multiple planes, superb contrast resolution, and differential physicochemical characteristics that are obtained without known toxicity. In practice, however, MRI has not been shown to differentiate consistently between normal and abnormal prostatic tissue. Although normal prostatic and periprostatic anatomy is clearly defined in T₁-weighted images, controversy persists as to the precise differential characteristics of inflammatory and neoplastic disease within the prostate. Thus, MRI is not presently adequate for prostate cancer screening. MRI has been shown to be superior to computerized axial tomography (CAT) for pelvic staging of prostate cancer; however, comparative studies involving other modalities with precise histologic confirmation are limited and the improvement reported is modest. There is some evidence that MRI may be helpful in the detection of prostate cancer metastatic to bone, but, again, information is limited. Substantial advances in MRI techniques such as optimal pulse sequencing, surface coils, and, possibly, paramagnetic contrast agents will be required to secure a role for MRI in prostate cancer evaluation.