The use of MRI in the diagnosis and staging of prostate cancer

Comparison of digital rectal examination, transrectal ultrasonography, and multicoil magnetic resonance imaging for preoperative evaluation of prostate cancer.
Sanchez-Chapado M, Angulo J C, Ibarburen C, Aguado F, Ruiz A, Viano J, Garcia-Segura J M, Gonzalez-Esteban J, Rodriguez-Vallejo J M.

EUROPEAN UROLOGY 1997: 32: 140-149.

Surgical cure of prostate cancer is potentially possible whenever the disease is confined to the gland and the surgical margins at resection are free of tumour. The selection of appropriate candidates for radical prostatectomy, however, remains a question of major concern. In this study, 20 consecutive patients undergoing radical retropubic prostatectomy were evaluated prospectively and 'blindly' by DRE, TRUS and MRI using integrated endorectal/pelvic phased-array (PPA) coils. In 2 patients the cancer had been found incidentally after TURP, 10 had a prostatic nodule and 8 patients had undergone biopsy of a suspicious gland on the basis of an elevated PSA level. After surgery, step sections of the entire gland were performed, and tumour volume and percentage of gland involved were calculated. DRE detected only 50% of the tumours preoperatively, TRUS detected 75% and MRI detected 95%. Histology revealed that the disease was not confined to the prostate in 8 patients. With regard to predicting extracapsular penetration, the accuracy was 60% for DRE and TRUS and 79% for MRI. The accuracy for preoperative assessment of tumour location in the apex was 30% for DRE, 47% for TRUS and 89% for MRI. Apical tumours are at increased risk of positive margins, especially when nerve-sparing surgery is intended, and MRI would appear to be very accurate in detecting tumours in this situation. The authors calculate that the inclusion of MRI in the clinical staging system deprives 15% of potentially curable men of surgery as a result of falsely detected extracapsular disease, but still prevents 34% from undergoing futile prostatectomy because of undetected extracapsular disease. While MRI would appear to be more sensitive than TRUS in the detection and staging of prostate cancer, its expense and inability to allow simultaneous histological confirmation mean than it is not likely to replace it.