UroToday - Documentation of prostate cancer (CaP) recurrence for a rising PSA following radiotherapy (XRT) primarily relies on a prostate biopsy. In the online edition of the British Journal of Urology International, a group headed by Dr. Mark Emberton evaluates the ability for magnetic resonance imaging (MRI) to detect locally recurrent CaP after XRT. The use of MR spectroscopy (MRS) and dynamic contrast enhancement (DCE-MRI) are suggested to detect local recurrence and validation has been by salvage prostatectomy or TRUS-guided biopsies. In the present study the investigators use transperineal template prostate biopsies with a 5-mm sampling frame. This has 95% sensitivity and avoids the selection bias of salvage prostatectomy and the undersampling of TRUS-guided biopsies.

This study cohort included 13 patients with confirmed biochemical recurrence after XRT. They underwent multiparametric (mp)-MRI with T2-weighted (T2W), DCE-MRI followed by transperineal template prostate biopsies. The imaging was performed using a 1.5 T scanner using a pelvic phased-array coil. Pre- and dynamic acquisition sequences after IV gadolinium contrast were obtained for analysis by two uro-radiologists. Each prostate was divided into 4 areas of interest - left and right anterior, and left and right posterior. This resulted in 52 paired datasets. A scoring system of 1-5 was used; 1 indicating no radiographic evidence of CaP and 5 was highly suspicious for CaP. The authors provide numerous details of how the radiographic subtleties resulted in the score.

Local staging of recurrent CaP based on mp-MRI was < T2 in seven men and > T3 in six men. Most patients had an interval between mp-MRI and biopsy of 5 months. Histologic assessment demonstrated CaP present in at least one prostate area in 11 of 13 patients, and of these 3 had CaP in one area, 4 in two areas, and 4 in three areas. No patient had CaP in all four areas. The AUC under the ROC curve was 0.77 for one uro-radiologist and 0.89 for the other. Using a definition of one cancer core containing > 3mm CaP in it, the AUC was 0.86 and 0.94 for the two radiologists. Radiographic detection accuracy was better in anterior compared with peripheral zone lesions.

Arumainayagam N, Kumaar S, Ahmed HU, Moore CM, Payne H, Freeman A, Allen C, Kirkham A, Emberton M
BJU Int. 2010 Mar 9. Epub ahead of print.

UroToday Contributing Editor Christopher P. Evans, MD, FACS

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