Predictive value of PI-RADS classification in MRI-directed transrectal ultrasound guided prostate biopsy

Clin Radiol. 2016 Apr;71(4):375-80. doi: 10.1016/j.crad.2016.01.001. Epub 2016 Feb 12.

Abstract

Aim: To correlate the results of transrectal ultrasound (TRUS)-guided targeted prostate biopsies (performed in the setting of at least one previous negative biopsy) with the Prostate Imaging Reporting and Data System (PI-RADS).

Material and methods: Fifty-two patients (mean age 64 years, range 52-76 years), with previous negative prostate biopsy underwent magnetic resonance imaging (MRI)-directed TRUS-guided targeted and sectoral biopsy. A retrospective review of MRI examinations was carried out, blinded to biopsy results. PI-RADS scores (T2, diffusion-weighted imaging [DWI] and overall) were assigned on a per lesion basis, and localised to sextants. The scores were correlated with biopsy results, and the positive predictive values (PPV) of PIRADS scores for positive biopsies were calculated.

Results: Overall, biopsies were positive in 23/52 (44.2%) patients. Eighty-one areas were targeted in 52 patients. On a per lesion basis, there was significant correlation between positive targeted biopsy and both T2 and overall PI-RADS score (p<0.001). The correlation between biopsy and DWI score was significant for peripheral zone tumours only, not for transitional zone tumours. The PPV of overall PI-RADS scores of 3, 4, and 5 were 10.6%, 44%, and 100%, respectively. The PPV of T2 PI-RADS scores of 3, 4, and 5 were 19.6%, 60%, and 100%, respectively. The PPV of DWI PI-RADS scores of 3, 4, and 5 were 50%, 27.3%, and 33%, respectively. When transitional tumours were excluded, the PPV of DWI PI-RADS 3, 4, and 5 were 40%, 43%, and 78%.

Conclusion: The PIRADS score provides an effective framework for determining the likelihood of prostate cancer on MRI. The DWI PI-RADS score correlates well with the presence of peripheral zone tumour on targeted biopsy, but not with transitional zone tumours.

MeSH terms

  • Aged
  • Biopsy
  • Cohort Studies
  • Humans
  • Magnetic Resonance Imaging*
  • Male
  • Middle Aged
  • Predictive Value of Tests
  • Prostate / diagnostic imaging
  • Prostate / pathology
  • Prostatic Neoplasms / diagnostic imaging
  • Prostatic Neoplasms / pathology*
  • Radiology Information Systems*
  • Reproducibility of Results
  • Retrospective Studies
  • Ultrasonography, Interventional*