In a study of 37,887 men 50 to 60 years old, those with PSA of >= 3 ng/ml underwent MRI imaging of the prostate and were randomized to systematic biopsy plus targeted biopsy or MRI-targeted biopsy only. MRI-directed targeted biopsy reduced the risk of overdiagnosis by half but did delay detection of intermediate-risk tumors in a small proportion of patients.