Should I get a prostate Magnetic Resonance Imaging (MRI) prior to biopsy?

Prostate MRI Before Biopsy: Current Recommendations

For initial prostate biopsies, MRI alone should not be used to determine whether to perform a biopsy, as it may miss clinically significant cancers in up to 6.7% of patients. 1 However, MRI has an important role in certain clinical scenarios, particularly for repeat biopsies.

Initial Biopsy Setting

Current Guidelines Recommend:

• Standard 12-core TRUS-guided biopsy remains the primary approach for initial prostate cancer detection 1
• MRI is not routinely recommended before initial biopsy 1
• A negative MRI is not a reason to forego biopsy in men with strong indications for first-time biopsy 1

Rationale Against Pre-Biopsy MRI for Initial Biopsies:

• Studies show that relying on MRI alone would miss clinically significant cancers:
  • In a prospective study of 223 biopsy-naïve men, not performing biopsies in men with PI-RADS 1/2 lesions would have missed 15 intermediate/high-risk tumors (6.7% of study population) 1
  • In another trial, 13 tumors with Gleason score 3+4 would have been missed in 53 evaluable men (24.5%) based on MRI results alone 1

Repeat Biopsy Setting

MRI is Strongly Recommended:

• For patients with prior negative TRUS-guided biopsies and persistent clinical suspicion of prostate cancer, MRI followed by targeted biopsy is appropriate 1
• The yield of standard repeat systematic biopsies decreases significantly after the second biopsy:
  • Second biopsy: 15-20% positive rate
  • Third biopsy: 8-17% positive rate
  • Fourth biopsy: 7-12% positive rate 1

Benefits of MRI in Repeat Biopsy Setting:

• Helps localize high-value targets for MRI-guided biopsy 1
• Improves detection of clinically significant cancer:
  • Cancer detection rates for targeted biopsies of suspicious lesions range from 34-51% in men with previous negative biopsies 1
  • Targeted biopsies detect more clinically significant cancers and fewer insignificant cancers compared to systematic biopsies 2

Combining Approaches for Optimal Detection

• Combined approach (systematic + targeted biopsies) provides the highest detection rate of clinically significant prostate cancer 3
• In the MRI-FIRST study:
  • 14% of clinically significant cancers were detected by systematic biopsy only
  • 20% were detected by targeted biopsy only
  • 66% were detected by both techniques 3
• Using a fusion-biopsy-only approach in men with an MRI suspicion score of ≥4 would miss only 3.5% of clinically significant prostate cancers 2

Technical Considerations

• Multiparametric MRI (mpMRI) provides superior soft tissue contrast for accurate detection of clinically significant lesions 4
• PI-RADS scoring system standardizes MRI reporting:
  • High-value targets (PI-RADS 4-5) are seen in approximately 49% of patients
  • Targeted biopsies of these lesions show high detection rates (86%) 4
• Reader experience significantly impacts diagnostic accuracy 4

Limitations of MRI

• Negative predictive value (NPV) of prostate MRI (76%-87%) is insufficient to allow omission of biopsy in the negative MRI setting 5
• Positive predictive value (PPV) of MRI (27%-44%) provides only incremental improvement over clinical tools 5
• Technical limitations in diffusion-weighted imaging and radiologist-to-radiologist variability affect accuracy 5

Conclusion

For initial biopsies, standard 12-core TRUS-guided biopsy remains the recommended approach, with MRI not routinely recommended before first biopsy. For patients with prior negative biopsies and persistent suspicion of prostate cancer, pre-biopsy MRI with subsequent targeted biopsies offers significant advantages in detecting clinically significant disease while potentially reducing detection of insignificant cancers.