Summary
Background Men with high serum prostate specifi c antigen usually undergo transrectal ultrasound-guided prostate
biopsy (TRUS-biopsy). TRUS-biopsy can cause side-eff ects including bleeding, pain, and infection. Multi-parametric
magnetic resonance imaging (MP-MRI) used as a triage test might allow men to avoid unnecessary TRUS-biopsy and
improve diagnostic accuracy.
Methods We did this multicentre, paired-cohort, confi rmatory study to test diagnostic accuracy of MP-MRI and
TRUS-biopsy against a reference test (template prostate mapping biopsy [TPM-biopsy]). Men with prostate-specifi c
antigen concentrations up to 15 ng/mL, with no previous biopsy, underwent 1·5 Tesla MP-MRI followed by both
TRUS-biopsy and TPM-biopsy. The conduct and reporting of each test was done blind to other test results. Clinically
signifi cant cancer was defi ned as Gleason score ≥4 + 3 or a maximum cancer core length 6 mm or longer. This study
is registered on ClinicalTrials.gov, NCT01292291.
Findings Between May 17, 2012, and November 9, 2015, we enrolled 740 men, 576 of whom underwent 1·5 Tesla MP-MRI
followed by both TRUS-biopsy and TPM-biopsy. On TPM-biopsy, 408 (71%) of 576 men had cancer with 230 (40%) of
576 patients clinically signifi cant. For clinically signifi cant cancer, MP-MRI was more sensitive (93%, 95% CI 88–96%)
than TRUS-biopsy (48%, 42–55%; p<0·0001) and less specifi c (41%, 36–46% for MP-MRI vs 96%, 94–98% for TRUSbiopsy;
p<0·0001). 44 (5·9%) of 740 patients reported serious adverse events, including 8 cases of sepsis.
Interpretation Using MP-MRI to triage men might allow 27% of patients avoid a primary biopsy and diagnosis of
5% fewer clinically insignifi cant cancers. If subsequent TRUS-biopsies were directed by MP-MRI findings, up to
18% more cases of clinically signifi cant cancer might be detected compared with the standard pathway of TRUS-biopsy
for all. MP-MRI, used as a triage test before fi rst prostate biopsy, could reduce unnecessary biopsies by a quarter.
MP-MRI can also reduce over-diagnosis of clinically insignifi cant prostate cancer and improve detection of clinically
signifi cant cancer.