DWI of Prostate Cancer: Optimal b-Value in Clinical Practice.

Aim. To compare the diagnostic performance of diffusion weighted imaging (DWI) using b-values of 1000 s/mm(2) and 2000 s/mm(2) at 3 Tesla (T) for the evaluation of clinically significant prostate cancer. Matherials and Methods. Seventy-eight prostate cancer patients underwent a 3T MRI scan followed by radical prostatectomy. DWI was performed using b-values of 0, 1000, and 2000 s/mm(2) and qualitatively analysed by two radiologists. ADC maps were obtained at b-values of 1000 and 2000 s/mm(2) and quantitatively analyzed in consensus. Results. For diagnosis of 78 prostate cancers the accuracy of DWI for the young reader was significantly greater at b = 2000 s/mm(2) for the peripheral zone (PZ) but not for the transitional zone (TZ). For the experienced reader, DWI did not show significant differences in accuracy between b-values of 1000 and 2000 s/mm(2). The quantitative analysis in the PZ and TZ was substantially superimposable between the two b-values, albeit with a higher accuracy with a b-value of 2000 s/mm(2). Conclusions. With a b-value of 2000 s/mm(2) at 3T both readers differentiated clinical significant cancer from benign tissue; higher b-values can be helpful for the less experienced readers.