Does body-coil magnetic-resonance imaging have a role in the preoperative staging of patients with clinically localized prostate cancer?

Abstract

To investigate the accuracy and use of body-coil magnetic resonance imaging (MRI) in the local staging of prostate cancer before radical prostatectomy (RP). Fifty-six patients undergoing RP were staged before surgery using body-coil MRI; none was denied surgery on the basis of their scan results. All scans were reported before RP by one of three consultant radiologists and afterward by a colleague with a special interest in prostate MRI, unaware of the patients' clinical details. The overall sensitivity of MRI at detecting extracapsular extension was 50% on general reporting and 72% when reported by the specialist radiologist; the respective specificities were 84% and 86%. Of the 55 patients included in the study, 18 (33%) had extracapsular disease on histological analysis. MRI was most accurate in the 17 patients at high-risk (prostate-specific antigen, PSA, >10 ng/mL and Gleason score >or= 8) and eight at intermediate risk (PSA < 10 ng/mL and Gleason score 7). In the former group with specialist analysis, the sensitivity was 100%, although this decreased to 67% with general reporting. Both gave a specificity of 82%. Intermediate risk disease gave a sensitivity and specificity of 75%, irrespective of reporting method. The ability of MRI to detect extraprostatic tumour in the 30 low-risk patients (PSA < 10 ng/mL and Gleason score 2-6) was poor; the sensitivity was 25% with general and 50% on specialist review, although both methods gave a specificity of >90%. Body-coil MRI is sensitive and specific for identifying extracapsular extension of prostate cancer in patients with high- or intermediate-risk disease. Patients at low risk frequently have microscopic extension which is not detected. Opinion from a radiologist with a special interest in prostate MRI can increase the reporting accuracy even when unaware of the patients' clinical details.