Tsutomu Tamada MD, PhD, Presenter: Nothing to Disclose

Teruki Sone MD, PhD, Abstract Co-Author: Nothing to Disclose

Yoshimasa Jo MD, PhD, Abstract Co-Author: Nothing to Disclose

Hiroki Higashi MD, Abstract Co-Author: Nothing to Disclose

Takenori Yamashita, Abstract Co-Author: Nothing to Disclose

Katsuyoshi Ito MD, Abstract Co-Author: Nothing to Disclose

To evaluate the utility of T2-weighted imaging (WI), dynamic contrast-enhanced MR imaging (DCE-MRI) and diffusion-weighted imaging (DWI) for the detectability of locally recurrent prostate cancer after high-dose-rate brachytherapy (HDR-BT), and to clarify locational characteristics of tumor recurrence.

Sixteen male patients (mean age, 69 years; range, 59-79 years) with biochemical failure after HDR-BT for prostate cancer underwent MR imaging of prostate gland before TRUS-guided systematic 12-core biopsy. T1WI, T2WI, DCE-MRI and DWI (using b-factors of 0 and 800 sec/mm2) were performed using a 1.5-T MR unit. According to the sites of biopsy, the prostate was divided into 8 regions (6 from peripheral zone (PZ) and 2 from transition zone (TZ)) on MR images. All regions were evaluated for each MR method on the following features: 1) detectability of locally recurrent tumor, 2) comparison between the biopsy results and the MRI findings in tumor location.

Biopsy demonstrated locally recurrent prostate cancer in 9 of 16 patients, 22 (17 in PZ, 5 in TZ) of 128 regions (17.2%). Sensitivity, specificity and accuracy of each MR method in the detection of recurrent tumor were 27%, 99%, 87% in T2WI, 52%, 99%, 91% in DCE-MRI, and 68%, 95%, 91% in DWI, respectively. The sensitivity of DWI to detect recurrent tumor was significantly higher than that of T2WI (P = 0.0039). Furthermore, combining all 3 methods of MR imaging distinctly improved the sensitivity (from 27-68% to 77%), although the specificity was slightly decreased (from 95-99% to 92%). The sensitivity of combined MRI method to detect tumor recurrence varied among the regions: 86% (6 of 7) in base, 71% (5 of 7) in middle, 100% (3 of 3) in apex, and 60% (3 of 5) in TZ. The sensitivity was substantially lower in TZ than in PZ (14 of 17 (82%)).

These results indicate that DWI combined with other MR imaging protocols is a sensitive method to detect local recurrence after HDR-BT. The detectability of recurrent tumor was substantially lower in TZ than in PZ as in the case with primary cancer.

MR imaging including DWI would be potentially useful for visualizing and detecting prostate cancer, even if performed after HDR-BT.

Tamada, T, Sone, T, Jo, Y, Higashi, H, Yamashita, T, Ito, K, Locally Recurrent Prostate Cancer after HDR Brachytherapy: Value of MR Imaging in Localizing Tumor and Correlation with Biopsy Findings.  Radiological Society of North America 2009 Scientific Assembly and Annual Meeting, November 29 - December 4, 2009 ,Chicago IL. http://archive.rsna.org/2009/8000941.html