Twelve-month prostate volume reduction after MRI-guided transurethral ultrasound ablation of the prostate.

PURPOSE: To quantitatively assess 12-month prostate volume (PV) reduction based on T2-weighted MRI and immediate post-treatment contrast-enhanced MRI non-perfused volume (NPV), and to compare measurements with predictions of acute and delayed ablation volumes based on MR-thermometry (MR-t), in a central radiology review of the Phase I clinical trial of MRI-guided transurethral ultrasound ablation (TULSA) in patients with localized prostate cancer. MATERIALS AND METHODS: Treatment day MRI and 12-month follow-up MRI and biopsy were available for central radiology review in 29 of 30 patients from the published institutional review board-approved, prospective, multi-centre, single-arm Phase I clinical trial of TULSA. Viable PV at 12 months was measured as the remaining PV on T2-weighted MRI, less 12-month NPV, scaled by the fraction of fibrosis in 12-month biopsy cores. Reduction of viable PV was compared to predictions based on the fraction of the prostate covered by the MR-t derived acute thermal ablation volume (ATAV, 55°C isotherm), delayed thermal ablation volume (DTAV, 240 cumulative equivalent minutes at 43°C thermal dose isocontour) and treatment-day NPV. We also report linear and volumetric comparisons between metrics. RESULTS: After TULSA, the median 12-month reduction in viable PV was 88%. DTAV predicted a reduction of 90%. Treatment day NPV predicted only 53% volume reduction, and underestimated ATAV and DTAV by 36% and 51%. CONCLUSION: Quantitative volumetry of the TULSA phase I MR and biopsy data identifies DTAV (240 CEM43 thermal dose boundary) as a useful predictor of viable prostate tissue reduction at 12 months. Immediate post-treatment NPV underestimates tissue ablation. KEY POINTS: • MRI-guided transurethral ultrasound ablation (TULSA) achieved an 88% reduction of viable prostate tissue volume at 12 months, in excellent agreement with expectation from thermal dose calculations. • Non-perfused volume on immediate post-treatment contrast-enhanced MRI represents only 64% of the acute thermal ablation volume (ATAV), and reports only 60% (53% instead of 88% achieved) of the reduction in viable prostate tissue volume at 12 months. • MR-thermometry-based predictions of 12-month prostate volume reduction based on 240 cumulative equivalent minute thermal dose volume are in excellent agreement with reduction in viable prostate tissue volume measured on pre- and 12-month post-treatment T2w-MRI.

Further reduction of disqualification rates by additional MRI-targeted biopsy with transperineal saturation biopsy compared with standard 12-core systematic biopsies for the selection of prostate cancer patients for active surveillance.

BACKGROUND: Active surveillance (AS) is commonly based on standard 10-12-core prostate biopsies, which misclassify ~50% of cases compared with radical prostatectomy. We assessed the value of multiparametric magnetic resonance imaging (mpMRI)-targeted transperineal fusion-biopsies in men under AS. METHODS: In all, 149 low-risk prostate cancer (PC) patients were included in AS between 2010 and 2015. Forty-five patients were initially diagnosed by combined 24-core systematic transperineal saturation biopsy (SB) and MRI/transurethral ultrasound (TRUS)-fusion targeted lesion biopsy (TB). A total of 104 patients first underwent 12-core TRUS-biopsy. All patients were followed-up by combined SB and TB for restratification after 1 and 2 years. All mpMRI examinations were analyzed using PIRADS. AS was performed according to PRIAS-criteria and a NIH-nomogram for AS-disqualification was investigated. AS-disqualification rates for men initially diagnosed by standard or fusion biopsy were compared using Kaplan-Meier estimates and log-rank tests. Differences in detection rates of the SB and TB components were evaluated with a paired-sample analysis. Regression analyses were performed to predict AS-disqualification. RESULTS: A total of, 48.1% of patients diagnosed by 12-core TRUS-biopsy were disqualified from AS based on the MRI/TRUS-fusion biopsy results. In the initial fusion-biopsy cohort, upgrading occurred significantly less frequently during 2-year follow-up (20%, P<0.001). TBs alone were significantly superior compared with SBs alone to detect Gleason-score-upgrading. NPV for Gleason-upgrading was 93.5% for PIRADS⩽2. PSA level, PSA density, NIH-nomogram, initial PIRADS score (P<0.001 each) and PIRADS-progression on consecutive MRI (P=0.007) were significant predictors of AS-disqualification. CONCLUSIONS: Standard TRUS-biopsies lead to significant underestimation of PC under AS. MRI/TRUS-fusion biopsies, and especially the TB component allow more reliable risk classification, leading to a significantly decreased chance of subsequent AS-disqualification. Cancer detection with mpMRI alone is not yet sensitive enough to omit SB on follow-up after initial 12-core TRUS-biopsy. After MRI/TRUS-fusion biopsy confirmed AS, it may be appropriate to biopsy only those men with suspected progression on MRI.

Evaluation of the ESUR PI-RADS scoring system for multiparametric MRI of the prostate with targeted MR/TRUS fusion-guided biopsy at 3.0 Tesla.

OBJECTIVES: To evaluate the Prostate Imaging Reporting and Data System (PI-RADS) proposed by the European Society of Urogenital Radiology (ESUR) for detection of prostate cancer (PCa) by multiparametric magnetic resonance imaging (mpMRI) in a consecutive cohort of patients with magnetic resonance/transrectal ultrasound (MR/TRUS) fusion-guided biopsy. METHODS: Suspicious lesions on mpMRI at 3.0 T were scored according to the PI-RADS system before MR/TRUS fusion-guided biopsy and correlated to histopathology results. Statistical correlation was obtained by a Mann-Whitney U test. Receiver operating characteristics (ROC) and optimal thresholds were calculated. RESULTS: In 64 patients, 128/445 positive biopsy cores were obtained out of 95 suspicious regions of interest (ROIs). PCa was present in 27/64 (42%) of the patients. ROC results for the aggregated PI-RADS scores exhibited higher areas under the curve compared to those of the Likert score. Sensitivity/Specificity for the following thresholds were calculated: 85 %/73 % and 67 %/92 % for PI-RADS scores of 9 and 10, respectively; 85 %/60 % and 56 %/97 % for Likert scores of 3 and 4, respectively [corrected. CONCLUSIONS: The standardised ESUR PI-RADS system is beneficial to indicate the likelihood of PCa of suspicious lesions on mpMRI. It is also valuable to identify locations to be targeted with biopsy. The aggregated PI-RADS score achieved better results compared to the single five-point Likert score. KEY POINTS: • The ESUR PI-RADS scoring system was evaluated using multiparametric 3.0-T MRI. • To investigate suspicious findings, transperineal MR/TRUS fusion-guided biopsy was used. • PI-RADS can guide biopsy locations and improve detection of clinically significant cancer. • Biopsy procedures can be optimised, reducing unnecessary negative biopsies for patients. • The PI-RADS scoring system may contribute to more effective prostate MRI.