Diffusion-weighted imaging in peripheral zone prostate cancer detection: comparison of different mathematical models and different b-value ranges

Objective: To assess the b-value range dependence and diagnostic performance of conventional mono-exponential apparent diffusion coefficient (ADC), intravoxel incoherent motion (IVIM)-derived parameters, and diffusion kurtosis imaging (DKI)-derived parameters for differentiation of prostate cancer and normal tissue in the peripheral zone. Methods: Diffusion - weighted magnetic resonance imaging (DWI) using 21 b-values (0-4500 s/mm²) of 56 patients with histologically proven peripheral zone prostate cancer was analyzed. The mean signal intensities of the regions of interest (ROIs) placed in benign and cancerous peripheral tissues on DWI were fitted using mono-exponential, bi-exponential, and kurtosis models. ADC, , D*, f, D_app, and K_app were estimated using four different ranges of b-values: 0-1000, 0-2000, 0-3200, 0-4500 s/mm². Receiver operating characteristic curve (ROC) analysis was performed to evaluate the diagnostic performance of the parameters. Results: All parameters except D* showed significant differences between cancerous and benign peripheral tissues in all 4 b-value ranges. The areas under the ROC curve (AUCs) of ADCs were comparable in the 0-3200 s/mm² and 0-4500 s/mm² b-value ranges (P = 0.980), and were significantly higher than that of 0-1000 s/mm² and 0-2000 s/mm² b-value ranges (P < 0.05 for all). The AUCs of ADC and K_app in 0-2000 s/mm² and 0-3200 s/mm² b-value ranges were similar (P = 0.07 and P = 0.954), and were significantly higher than that of other parameters (P < 0.001 for all). The AUC of ADCs in 0-4500 s/mm² b-value range was significantly higher than that of K_app (P = 0.002). The AUCs of both ADCs and K_app were significantly higher than that of other parameters (P < 0.001 for all). Conclusion: There is no obvious advantage for IVIM- or DKI-derived parameters compared to ADC for differentiating cancerous from benign prostate tissue. ADC derived from conventional mono-exponential high b-value (3200 s/mm²) is an optimal parameter for peripheral zone prostate cancer detection. (authors)