Prostate volume measurement by multiparametric magnetic resonance and transrectal ultrasound: comparison with surgical specimen weight

OBJECTIVE: To assess accuracy of multiparametric magnetic resonance of the prostate to estimate gland volume, comparing the results with transrectal ultrasound and surgical specimen. METHODS: A retrospective study of 85 patients who underwent multiparametric magnetic resonance and transrectal ultrasound (for fusion image-guided biopsy) before radical prostatectomy. Prostate measurements were obtained from magnetic resonance axial and sagittal T2-weighted images and ultrasound; the prostate volume was determined using the ellipsoid formula. The results were compared with the surgical specimen weight. Maximum interval between multiparametric magnetic resonance imaging, transrectal ultrasound, and prostatectomy was 6 months. RESULTS: The prostate volume measured by multiparametric magnetic resonance imaging was 18-157cm(3) (mean of 49.9cm(3)) and by transrectal ultrasound, 22-165cm(3) (mean of 54.9cm(3)); the surgical specimen weight was 20-154g (mean of 48.6g), with no statistical differences. Based on the values obtained from imaging examinations, the prostate volume obtained was very close to the real prostatic weight, and the measures by multiparametric magnetic resonance were slightly more precise. CONCLUSION: Prostate volume measured by multiparametric magnetic resonance imaging and transrectal ultrasound showed similar values, and excellent agreement with real prostate weight of the surgical specimens. Prostate volume measured by magnetic resonance has been increasingly used in the clinical practice, and its value enables appropriate therapeutic planning and control of patients.