Prostate cancer detection using quantitative T2 and T2-weighted imaging: The effects of 5-alpha-reductase inhibitors in men on active surveillance

Background: T-2-weighted imaging (T-2-WI) information has been used in a qualitative manner in the assessment of prostate cancer. Quantitative derivatives (T-2 relaxation time) can be generated from T-2-WI. These outputs may be useful in helping to discriminate clinically significant prostate cancer from background signal. Purpose/Hypothesis: To investigate changes in quantitative T-2 parameters in lesions and noncancerous tissue of men on active surveillance for prostate cancer taking dutasteride 0.5mg or placebo daily for 6 months. Study Type: Retrospective. Population/Subjects: Forty men randomized to 6 months of daily dutasteride (n=20) or placebo (n=20). Field Strength/Sequence: Multiparametric 3T MRI at baseline and 6 months. This included a multiecho MR sequence for quantification of the T-2 relaxation times, in three regions of interest (index lesion, noncancerous peripheral [PZ] and transitional [TZ] zones). A synthetic signal contrast (T(2)Q contrast) between lesion and noncancerous tissue was assessed using quantitative T-2 values. Signal contrast was calculated using the T-2-weighted sequence (T2W contrast). Assessment: Two radiologists reviewed the scans in consensus according to Prostate Imaging Reporting and Data System (PI-RADS v. 2) guidelines. Statistical Tests: Wilcoxon and Mann-Whitney U-tests, Spearman's correlation. Results: When compared to noncancerous tissue, shorter T-2 values were observed within lesions at baseline (83.5 and 80.5 msec) and 6 months (81.5 and 81.9 msec) in the placebo and dutasteride arm, respectively. No significant differences for T2W contrast at baseline and after 6 months were observed, both in the placebo (0.40 [0.29-0.49] vs. 0.43 [0.25-0.49]; P=0.881) and dutasteride arm (0.35 [0.24-0.47] vs. 0.37 [0.22-0.44]; P=0.668). There was a significant, positive correlation between the T(2)Q contrast and the T2W contrast values (r=0.786; P < 0.001). Data Conclusion: The exposure to antiandrogen therapy did not significantly influence the T-2 contrast or the T-2 relaxation values in men on active surveillance for prostate cancer. Technical Efficacy: Stage 2