Diffusion-weighted imaging to evaluate for changes from androgen deprivation therapy in prostate cancer

OBJECTIVE. The objective of our study was to investigate the usefulness of apparent diffusion coefficient (ADC) values in evaluating for therapeutic changes from androgen deprivation therapy (ADT) in prostate cancer patients. MATERIALS AND METHODS. Forty-eight patients with prostate cancer treated with ADT were enrolled in this retrospective study. Diffusion-weighted imaging (DWI) at 3 T was performed before and after ADT. Before and after treatment, ADC values were measured in the tumors and in the benign tissues of the prostate, and serum prostate-specific antigen (PSA) levels and prostate volumes were also assessed. Statistical analysis was performed using a paired Student t test, Wilcoxon signed rank test, and Spearman rank correlation. RESULTS. In 48 patients, 55 tumors were identified. After treatment, the mean ADC value of the tumors (1.06 × 10-3 mm2/s) was significantly increased as compared with the pretreatment value (0.78 × 10-3 mm2/s) (p <0.001), whereas the ADC values of the benign tissues after treatment were significantly decreased compared with the pretreatment values (p <0.001). The mean prostate volume and mean PSA level were significantly reduced from 42.8 cm3 and 153.60 ng/mL before treatment to 21.4 cm3 and 9.51 ng/mL, respectively, after treatment (p <0.001). Changes in tumor ADC values showed a weak negative correlation with changes in PSA levels after treatment (correlation coefficient, ρ = -0.320; p = 0.028). CONCLUSION. DWI may have potential as a noninvasive tool for monitoring changes in response to ADT in prostate cancer patients.