Introduction:

Multiparametric magnetic resonance imaging (mpMRI) and transrectal ultrasound (TRUS) are used to estimate prostate volume and prostate specific antigen density (PSAD) in men with clinical suspicion of prostate cancer (PCa). Whether discordant measurements impact PCa detection is unknown.

Methods:

Patients referred for mpMRI prior to mpMRI-TRUS fusion-guided prostate biopsy between 2015 and 2020 were identified. Volume and calculated PSAD by mpMRI and TRUS were compared. Associations with presence of Gleason ≥3+3 and Gleason ≥3+4 PCa were evaluated using linear regression (interaction by volume quartile), logistic regression, and receiver operating characteristics.

Results:

Among 640 men, TRUS underestimated prostate volume relative to mpMRI (median 49.2 cc vs. 54.1 cc) with 8% lower volume per cc up to 77.5 cc (1^st-3^rd quartile) and 39% lower volume per additional cc above 77.5 cc (4^th quartile). mpMRI PSAD had slightly higher odds compared to TRUS PSAD for detection of Gleason ≥3+3 (OR 2.94 and OR 2.78, both p<0.001) and Gleason ≥3+4 (OR 4.20 and OR 4.02, both p<0.001) PCa. AUC improvements were of borderline significance for mpMRI vs. TRUS PSAD for Gleason ≥3+3 (0.689 vs. 0.675, p=0.05) and not significant for Gleason ≥3+4 (0.732 vs. 0.722, p=0.20).

Conclusion:

TRUS underestimates prostate volume relative to mpMRI. PSAD based on mpMRI may be better associated with detection of PCa compared to TRUS but the clinical significance is minimal.

Funding: Efforts to support data extraction and maintenance of The Prospective Loyola University mpMRI Prostate Biopsy Cohort database is supported by funding from Siemens Medical Solutions USA, Inc.