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

AIMS - 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).

MATERIALS 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%.

CONCLUSIONS - 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.

Clinical radiology. 2016 Feb 12 [Epub ahead of print]

E NiMhurchu, F O'Kelly, I G Murphy, L P Lavelle, C D Collins, G Lennon, D Galvin, D Mulvin, D Quinlan, C J McMahon

St Vincent's University Hospital, Elm Park, Dublin 4, Ireland. , St Vincent's University Hospital, Elm Park, Dublin 4, Ireland. , St Vincent's University Hospital, Elm Park, Dublin 4, Ireland. , St Vincent's University Hospital, Elm Park, Dublin 4, Ireland. , St Vincent's University Hospital, Elm Park, Dublin 4, Ireland. , St Vincent's University Hospital, Elm Park, Dublin 4, Ireland. , St Vincent's University Hospital, Elm Park, Dublin 4, Ireland. , St Vincent's University Hospital, Elm Park, Dublin 4, Ireland. , St Vincent's University Hospital, Elm Park, Dublin 4, Ireland. , St Vincent's University Hospital, Elm Park, Dublin 4, Ireland; Department of Radiology, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA 02215, USA.  

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