MR-IMAGING EVALUATION WITH A TRANSRECTAL SURFACE COIL OF LOCAL RECURRENCE OF PROSTATIC-CANCER IN MEN WHO HAVE UNDERGONE RADICAL PROSTATECTOMY

OBJECTIVE. The objective of this study was to evaluate the ability of transrectal surface coil MR imaging to reveal local recurrence of mali gnancy in men who have had radical prostatectomy for prostatic adenoca rcinoma. SUBJECTS AND METHODS. We performed prospective analysis of 41 men who had undergone radical prostatectomy (range of time since surg ery, 8 months to 5 years; mean, 26 months), 35 of whom had clinical su spicion of recurrent prostatic cancer and the remaining six of whom ha d no clinical evidence of recurrent prostatic cancer (controls). Our i maging used a transrectal surface coil on a 1.5-T MR scanner. Sagittal and axial fat-saturated T2-weighted fast spin-echo as well as axial T 1-weighted unenhanced and gadolinium-enhanced MR images of the prostat ic bed were acquired in all patients. Thirty-one of the 35 men with cl inical suspicion of recurrent prostatic cancer had elevated prostate-s pecific antigen (PSA) levels (greater than or equal to 0.4 ng/ml), and 22 of these 31 men had a palpable prostatic bed nodule or induration. The four of 35 men with clinical suspicion of recurrent prostatic can cer who had PSA levels less than 0.4 ng/ml had a palpable prostatic be d nodule or induration. Transrectal biopsy of the prostatic bed was di rected by digital palpation or transrectal sonography in all 35 men wi th clinical suspicion of recurrent malignancy. RESULTS. Thirty-one of the 35 men who had clinical suspicion of local recurrence of prostatic cancer had a soft-tissue nodule revealed in the prostatic bed by tran srectal surface coil MR imaging. Compared with the adjacent muscle, al l nodules were isointense on the T1-weighted images, hyperintense on t he T2-weighted images, and enhanced with gadolinium administration. Th e 22 patients who had an abnormal MR scan and a palpable nodule or ind uration and the nine patients with elevated PSA levels, no palpable ab normality, and an abnormality revealed by MR imaging underwent transre ctal biopsy; all had recurrent prostatic cancer proven by histology. I n the four patients with a palpable prostatic bed nodule or induration and normal PSA levels, MR imaging showed no distinct soft-tissue nodu le or area of enhancement in the prostatic bed; transrectal biopsy of the palpable nodule or induration yielded fibrosis but no malignancy i n all four patients. In the six control patients with no clinical evid ence of local recurrence, MR imaging revealed no evidence of recurrent malignancy; all six control patients continue to have no clinical evi dence of recurrent prostatic cancer with a minimum follow-up of 22 mon ths. Thus, the sensitivity of MR imaging in revealing local recurrence of prostatic cancer was 100% (95% confidence interval = 89-100%), and the specificity also was 100% (95% confidence interval = 69-100%). Th e kappa coefficient was 1.0 (p < .001). CONCLUSION. MR imaging with a transrectal surface coil is a useful imaging tool to evaluate men who have undergone radical prostatectomy and are suspected of having local recurrence of malignancy in the prostatic bed.