This prospective, randomised dual-blind study showed an increase in ADC and a decrease in conspicuity of prostate cancer lesions in men undergoing therapy with dutasteride. 

Giganti F, Moore CM, Robertson NL, McCartan N, Jameson C, Bott SRJ, Winkler M, Gambarota G, Whitcher B, Castro R, Emberton M, Allen C, Kirkham A. MRI findings in men on active surveillance for prostate cancer: does dutasteride make MRI visible lesions less conspicuous? Results from a placebo-controlled, randomised clinical trial. Eur Radiol. 2017 May 18. doi: 10.1007/s00330-017-4858-0. [Epub
ahead of print] PubMed PMID: 28523355