High-b-Value Diffusion-Weighted Imaging at 3 T to Detect Prostate Cancer: Comparisons Between b Values of 1,000 and 2,000 s/mm(2)

OBJECTIVE. The objective of our study was to investigate the diagnostic performance of 3-T MRI of the prostate using diffusion-weighted imaging (DWI) with high b values (1,000 and 2,000 s/mm(2)) and a phased-array coil in predicting localized prostate cancer. MATERIALS AND METHODS. Forty-eight patients underwent single-shot echo-planar DWI at 3 T, followed by radical prostatectomy. DWI was performed at high b values of 1,000 and 2,000 s/mm(2). Apparent diffusion coefficient (ADC) maps were analyzed by visual and quantitative assessment for tumor and benign tissue in the peripheral and transition zones. The visual and quantitative results of ADC maps obtained at b values of 1,000 and 2,000 s/mm(2) were compared with the histopathologic findings. RESULTS. To predict localized prostate cancer, the sensitivity of ADC maps obtained at a b value of 1,000 versus 2,000 s/mm(2) was 88% and 71%, respectively, and the accuracy was 89% and 86% (p < 0.01). The mean ADC values of tumors in both the peripheral and transition zones were significantly lower than those of benign tissues at both b values of 1,000 and 2,000 s/mm(2) (p < 0.001). CONCLUSION. Prostate DWI performed at 3 T using high b values was able to improve differentiation of tumors from benign tissue. DWI performed using a b value of 1,000 s/mm(2) was more sensitive and more accurate in predicting localized prostate cancer than DWI performed using a b value of 2,000 s/mm(2).