Efficacy evaluation of apparent diffusion coefficient from diffusion weighted imaging in identifying intermediate and high grade prostate cancer

Objective: To evaluate the utility of apparent diffusion coefficient (ADC) values from DWI in identifying intermediate and high grade prostate cancer (patients harboring Gleason 4 and/or 5 components in their radical prostatectomy specimens). Methods: We retrospectively analyzed the DWI of 54 patients with biopsy-proven prostate cancer and biopsy Gleason score (GS) ≤ 3 + 3 = 6. These patients were divided into two groups, intermediate and high grade prostate cancer (patients harboring Gleason 4 and/or 5 components in their radical prostatectomy specimens) and low-grade prostate cancer (patients not harboring Gleason 4 and/or 5 components in their radical prostatectomy specimens). ROIs were drawn on areas of the most suspicious lesion on T₂WI and the ADC values were calculated. The ADC values of the two groups were compared to determine whether there were differences between them with independent-sample t test. Receiver operating characteristic (ROC) curve was used to determine the ability of ADC values in differentiating intermediate/high grade prostate cancer from low-grade prostate cancer. Results: Twenty-eight patients had intermediate and high grade prostate cancer while the other twenty-six ones had low-grade prostate cancer. Significant differences were found for the ADC values of these two groups [(0.905 ± 0.162) × 10^-3 mm²/s vs. (1.143 ± 0.165) × 10^-3 mm²/s, t = 5.361, P < 0.011. The area under the ROC curve of ADC in differentiating intermediate and high grade prostate cancer from low-grade prostate cancer was 0.861, with sensitivity of 88.5% and specificity of 67.9% at the cut-off of 1.000 × 10^-3 mm²/s. Conclusion: The ADC values of suspicious areas in prostate contribute to identify intermediate/high grade prostate cancer in patients with a GS ≤ 3 + 3 = 6 on biopsy. (authors)