Prostate cancer detection using quantitative T 2 and T 2 -weighted imaging: The effects of 5-alpha-reductase inhibitors in men on active surveillance

Abstract

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 0.5 mg 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 (T 2 W 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 T 2 W 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 T 2 W 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. Level of Evidence: 4. Technical Efficacy: Stage 2. J. Magn. Reson. Imaging 2018;47:1646–1653.