Biparametric MRI Improves Detection of Significant PCa
The technique requiring no intravenous contrast media and is faster and simpler to perform than multiparametric MRI (15 vs 40 minutes).
Performing MRI can be expensive and time-consuming, and it would be a major challenge for any health care system to systematically use mpMRIs to diagnose prostate cancer before all biopsies. However, the results confirm that a more rapid and simple bpMRI approach is feasible, is sufficient for MRI/TRUS [transrectal ultrasound] image fusion, and provides an accurate sector map of the prostate for targeted biopsies.
The team tested bpMRI in 1020 men with PSA of 5.7 to 13.0 ng/mL. All men underwent TRUS-guided biopsy followed by bpMRI targeted biopsy.
Combined, biopsies detected PCa in 64% and clinically significant PCa of Gleason 4+3 and above (or Gleason 3+4 in more than 50% of a core) in 40%. Restricting biopsies to men with suspicious bpMRI findings, however, would allow 30% of men to avoid biopsy.
Results showed that bpMRI-targeted biopsy improved detection of significant PCa by 11% and reduced overdetection of insignificant cancers by 40% compared with standard biopsies alone. In addition, bpMRI had a high negative predictive value (97%) in ruling out significant PCa. Only 8 men with significant PCa would have been missed using the test.
While methodologically rigorous and transparently reported, several issues deserve mention. For example, bpMRI targeted biopsy was not compared with template-guided prostate mapping biopsy, as used in the PROMIS study, they noted. The test also had "less impressive" specificity (48%) and positive predictive values (56%).
For many men, higher health care value would be achieved by screening and treating fewer men rather than screening widely with routine follow-up imaging triage techniques.
Boesen L, Nørgaard N, Løgager V, et al. Assessment of the diagnostic accuracy of biparametric magnetic resonance imaging for prostate cancer in biopsy-naïve men: The Biparametric MRI for Detection of Prostate Cancer (BIDOC) Study. JAMA Network Open. 2018;1(2):e180219. doi:10.1001/jamanetworkopen.2018.0219
Wilt TJ and Dahm P. Magnetic resonance imaging-based prostate cancer screening: Is high-value care achieved or does the Holy Grail remain elusive? JAMA Network Open. 2018;1(2):e180220. doi:10.1001/jamanetworkopen.2018.0220