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

International audienceBackground - T -weighted imaging (T -WI) information has been used in a qualitative manner in the assessment of prostate cancer. Quantitative derivatives (T relaxation time) can be generated from T -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 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 relaxation times, in three regions of interest (index lesion, noncancerous peripheral [PZ] and transitional [TZ] zones). A synthetic signal contrast (T Q contrast) between lesion and noncancerous tissue was assessed using quantitative T values. Signal contrast was calculated using the T -weighted sequence (T 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 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 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 Q contrast and the T W contrast values (r = 0.786; P < 0.001). Data conclusion - The exposure to antiandrogen therapy did not significantly influence the T contrast or the T 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