Comparative effectiveness of [18F]-Fluorocholine PET-CT and pelvic MRI with diffusion-weighted imaging in the primary and lymph node staging of high risk prostate cancer: Data from 47 prospectively enrolled patients

399 Objectives Evaluate and compare the performances of PET-CT with fluorine-18 labelled choline (18F-Choline) and MR with diffusion-weighted imaging (DWI) in the staging of high risk Pca. Methods Data from 97 patients enrolled prospectively in a clinical trial (EudraCT number 2009-014839-21) evaluating the interest of 18F-Choline in staging of high-risk Pca were studied. We only studied 47 patients with available pre-therapeutic DWI MRI who undergone surgical treatment with either prostatectomy and/or LN dissection.Diagnostic performances were determined for each of prostate sextants, capsula invasion, seminal vesicles and lymph node invasion for both PET-CT and DWI MRI. A box plot and ROC curve were established to identify an efficient SUV threshold. Results Median age was 63 years; mean PSA was 23 ng/mL; Repartition of Gleason score from 6 to 9. In a region-based LN analysis, sensitivity and specificity were 56% and 98% for 18F-Choline, and 17% and 99% for DWI MRI respectively. In a patient-based analysis sensitivity and specificity were 78% and 94% for 18F-Choline and 33% and 91% for DWI MRI respectively. Out of the 222 prostate sextants, 170 were invaded. Visual analysis had a sensitivity and specificity of 91% and 38% for 18F-Choline and 74% and 60% for DWI MRI respectively. Conclusions In this study, 18F-Choline might provide helpful additional information in the staging of high risk Pca in comparison with DWI MRI, especially so in the evaluation of lymph node involvement due to its high sensitivity and excellent specificity.