Yuji Watanabe MD, Abstract Co-Author: Nothing to Disclose

Masako Nagayama MD, Abstract Co-Author: Nothing to Disclose

Shigeo Ichihashi MD, Presenter: Nothing to Disclose

Tohru Araki MD, Abstract Co-Author: Nothing to Disclose

Akira Okumura, Abstract Co-Author: Nothing to Disclose

Takayoshi Ishimori MD, Abstract Co-Author: Nothing to Disclose

Prostatic MR imaging has been mainly used to identify malignant lesions detected by systematic biopsy and to define its extent such as extracapsular invasion etc. However the detectability of prostate cancer by systematic biopsy has not been very high and, extended systematic biopsy or template biopsy has come to be performed. Recently, apparent diffusion coefficient (ADC) map was reported to be useful in the detection of prostatic cancer. Therefore, we postulate that if a biopsy is performed to target at lesions suspected of cancer by ADC map, detectability of prostate cancer could increase. The purpose of this study was to characterize lesions of low ADC value by targeted biopsy and histological examination.

This study included 291 prostatic lesions (mean size: 13.53mm, range from 5 to 51mm) in 179 patients (mean age: 71 years old, range from 51 to 88) with PSA level of 4.0 or higher (average 10.1, range from 4.01 to 49.18). Prostatic MR imaging was performed using cardiac synergy coil. Transaxial and coronal T2-TSE, diffusion-weighted imaging (b value: 600) and dynamic contrast-enhanced FS-T1 TSE images were obtained. Lesions of ADC value less than 1.35x10-3 mm2/sec were sampled by targeted biopsy. Targeted biopsy was performed to obtain two or three samples of each lesion. MR findings were compared with histopathological results.

Among 291 lesions examined by targeted biopsy, total 148 lesions (51 %) proved to be adenocarcinoma. The location of the malignant lesions included 72 lesions (49 %) in the peripheral zone and 76 lesions (51 %) in the transition zone. The positive ratio of the lesions was 57 % in the peripheral zone and 46 % in the transition zone. The others were non-malignant lesions including degenerative change, prostatitis, prostatic intraepithelial neoplasia (PIN) in the peripheral zone, and hyperplastic nodule, atypical basal cell or adenomatous hyperplasia and PIN in the transitional zone.

ADC-low lesions include not only prostate cancer but also benign or border-lined lesions. In combination with targeted biopsy, prostatic cancer could be detected and located accurately.

ADC map based on diffusion-weighted imaging can be useful to screen patients with high PSA level for prostate biopsy, and could help urologists to increase confidence to perform targeted biopsy.

Watanabe, Y, Nagayama, M, Ichihashi, S, Araki, T, Okumura, A, Ishimori, T, Detection and Localization of Prostate Cancer with ADC Map and Targeted Biopsy.  Radiological Society of North America 2008 Scientific Assembly and Annual Meeting, February 18 - February 20, 2008 ,Chicago IL. http://archive.rsna.org/2008/6019128.html