RESUMO
Background and purpose:With the widespread use of screening of prostate-specific antigen (PSA) levels, prostate cancers at organ-conifned stage are increasing in newly diagnosed cases. However, some defects remain in conventional monoexponential diffusion-weighted imaging (DWI) for differentiating organ-conifned prostate cancer from benign lesions. Therefore, the aim of this study was to obtain biexponential apparent diffusion parameters of prostate organ-conifned cancer, chronic prostatitis in peripheral zone (PZ) and normal PZ tissue, and to compare with monoexponential apparent diffusion coeffcient (ADC) for differentiating prostate cancer from prostatitis lesions. Methods:Sixteen patients with pathologically confirmed prostate organ-confined cancer in PZ, 14 with prostatitis underwent conventional (b-factors 0, 1 000 s/mm2) and 10b-factors (0-3 000 s/mm2) diffusion-weighted imaging (DWI).The monoexponential ADC value and biexponential parameters fast ADC (ADCf), fraction of ADCf (f), slow ADC (ADCs) value for prostate cancer, prostatitis and normal tissues were calculated and compared. Receiver operating characteristic analysis was performed for those parameters.Results:Biexponential and monoexponential parameters were obtained for 18 prostate cancers, 18 prostatitis and 37 normal PZ tissues. The ADC value of prostate cancer tissues was remarkably lower [(0.83±0.11)×10-3 mm2/s] than that of other tissues (P0.01), but the AUC off and ADCs in differ-entiating cancer from prostatitis (0.83 and 0.80) were signiifcantly lower than that of ADC (P<0.01).Conclusion:The biexponential DWI provided additional tissue characterization parameters for different prostate tissues. ADCf yielded comparable accuracy with ADC in identiifcation of prostate organ-conifned cancer. The biexponential parameter could further improve the diagnostic effcacy.