18F-choline PET/mpMRI for detection of clinically significant prostate cancer

Abstract

A prospective single-arm clinical trial was conducted to determine if 18F-choline PET/mpMRI can improve the specificity of multi-parametric prostate MRI (mpMRI) for Gleason ≥ 3+4 prostate cancer. Methods: Before targeted and systematic prostate biopsy, mpMRI and 18F-choline PET/CT were performed in 56 evaluable subjects with 90 Likert score 3-5 mpMRI target lesions, using a 18F-choline target-to-background ratio (TBR) of >1.58 to indicate a positive 18F-choline result. Prostate biopsies were performed after registration of real-time transrectal ultrasound with T2-weighted MRI. A mixed-effects logistic regression was applied to measure the performance of mpMRI (based on prospective Likert and retrospective Prostate Imaging - Reporting and Data System version 2 [PI-RADS v2] scores) compared to 18F-choline PET/mpMRI to detect Gleason ≥ 3+4 cancer. Results: The per-lesion accuracy of systematic plus targeted biopsy for mpMRI alone was 67.8% (area under receiver operator characteristic curve [AUC] 0.73) for Likert 4-5, and 70.0% (AUC 0.76) for PI-RADS 3-5. Several PET/MRI models incorporating of 18F-choline with mpMRI data were investigated. The most promising model selected all high-risk disease on mpMRI (Likert 5 or PI-RADS 5) plus low- and intermediate risk disease (Likert 4 or PI-RADS 3-4) with elevated 18F-choline TBR >1.58 as positive for significant cancer. Using this approach, the accuracy on a per-lesion basis significantly improved to 88.9% for Likert (AUC 0.90, p<0.001) and 91.1% (AUC 0.92, p<0.001) for PI-RADS v2. On a per-patient basis, the accuracy improved to 92.9% for Likert (AUC 0.93, p<0.001) and to 91.1% (AUC 0.91, P = 0.009) for PI-RADS v2. Conclusion:18F-choline PET/mpMRI improved the identification of Gleason ≥ 3+4 prostate cancer compared to mpMRI with the principal effect being improved risk-stratification of intermediate-risk mpMRI lesions.