Can magnetic resonance-ultrasound fusion biopsy improve cancer detection in enlarged prostates?

PURPOSE: Patients with an enlarged prostate and suspicion of prostate cancer pose a diagnostic dilemma. The prostate cancer detection rate of systematic 12-core transrectal ultrasound guided biopsy is between 30% and 40%. For prostates greater than 40 cc this decreases to 30% or less. Magnetic resonance-ultrasound fusion biopsy has shown superior prostate cancer detection rates. We defined the detection rate of magnetic resonance-ultrasound fusion biopsy in men with an enlarged prostate gland. MATERIALS AND METHODS: We retrospectively analyzed the records of patients who underwent multiparametric prostate magnetic resonance imaging followed by magnetic resonance-ultrasound fusion biopsy at our institution. Whole prostate volumes were calculated using magnetic resonance imaging reconstructions. Detection rates were analyzed with respect to age, prostate specific antigen and whole prostate volumes. Multivariable logistic regression was used to assess these parameters as independent predictors of prostate cancer detection. RESULTS: We analyzed 649 patients with a mean±SD age of 61.8±7.9 years and a median prostate specific antigen of 6.65 ng/ml (IQR 4.35-11.0). Mean whole prostate volume was 58.7±34.3 cc. The overall detection rate of the magnetic resonance-ultrasound fusion platform was 55%. For prostates less than 40 cc the detection rate was 71.1% compared to 57.5%, 46.9%, 46.9% 33.3%, 36.4% and 30.4% for glands 40 to 54.9, 55 to 69.9, 70 to 84.9, 85 to 99.9, 100 to 114.9 and 115 cc or greater, respectively (p<0.0001). Multivariable logistic regression showed a significant inverse association of magnetic resonance imaging volume with prostate cancer detection, controlling for age and prostate specific antigen. CONCLUSIONS: Transrectal ultrasound guided and fusion biopsy cancer detection rates decreased with increasing prostate volume. However, magnetic resonance-ultrasound fusion biopsy had a higher prostate cancer detection rate compared to that of transrectal ultrasound guided biopsy in the literature. Magnetic resonance-ultrasound fusion biopsy represents a promising solution for patients with suspicion of prostate cancer and an enlarged prostate.

MRI characterization of the dynamic effects of 5α-reductase inhibitors on prostate zonal volumes.

INTRODUCTION: Prior studies of volumetric effects of 5α-reductase inhibitors (5ARIs) on the prostate have used transrectal ultrasound which provides poor differentiation of prostatic zones. We utilized high-resolution prostate MRI to evaluate the true dynamic effects of 5ARI in men who underwent multiple MRIs. MATERIALS AND METHODS: A retrospective study of patients who underwent serial 3.0 Tesla prostate MRI from 2007 to 2012 and were treated with 5ARI were studied. Nineteen patients who had a baseline MRI prior to 5ARI initiation and subsequent MRI follow up were selected. A randomly selected group of 40 patients who had not received any form of therapy was selected as the control cohort. Total prostate volume (TPV), transition zone volume (TZV), and peripheral zone volume (PZV) were calculated using 3D reconstructions and prostate segmentation from T2-weighted MRI. Changes in volumes were correlated with the duration of treatment using linear regression analysis. RESULTS: Following over 2 years of treatment, 5ARI decreased TPV significantly (16.7%, p < 0.0001). There were similar decreases in TZV (7.5%, p < 0.001) and PZV (27.4%, p = 0.0002) from baseline. In the control group, TPV and TZV increased (p < 0.0001) while PZV remained stable. When adjusted for the natural growth of prostate zonal volume dynamics seen in the control cohort, approximately 60% of the reduction of the TPV from 5ARI resulted from changes in the TZV and 40% of the reduction from changes in the PZV. CONCLUSIONS: 3.0 Tesla MRI characterizations of the dynamic effects of 5ARI on prostate zonal volumes demonstrate significant decreases in TPV, TZV, and PZV. 5ARI blocks the natural growth of TZV as men age and decreases both TZV and PZV below their baselines. As imaging technology improves, prostate MRI allows for more accurate assessment of drug effects on dynamic prostate volumes.