18F-choline PET/MR in the initial staging of prostate cancer. Impact on the therapeutic approach

Abstract

AimEvaluate the therapy impact of initial staging in patients diagnosed with prostate cancer by 18F-Choline PET/MRI hybrid technique. MaterialA prospective study which included 31 patients diagnosed with prostate cancer; Gleason >7; mean PSA 13.6 ng/mL (range 6.3–20.6) PET/MRI studies were acquired simultaneously with hybrid equipment (SIGNA.3T, GE) following intravenous injection of 185 ± 18.5 MBq of 18F-Choline:- Early/prostate imaging: PET emission + Multiparametric MR: DIXON-T1-T2-diffusion-gadolinium.- Late/whole-body imaging: PET emission + MR: DIXON-T1-T2-diffusion-STIR sequences. Images were visually evaluated. SUV & ADC & Textures were also calculated. Treatment selection was based upon Oncology Committee consensus decision. ResultsProcedure was well tolerated in all patients, and no artefacts were reported. MRI was superior in T staging in 8 patients (25.8%) (Likert: 2–3), whereas PET increased MRI sensitivity in 3 patients (9.7%) (PIRADS: 3). Prostate lesion locationPeripheral 91.4%, transitional 8.6%. SUVmax threshold: 2.95: sensitivity 92.9%, specificity 66.7%. No correlation SUV vs ADC. Radiomics: Better distinctiion between stage T2 vs T3 using the DiscrLin model with NG = 16 (AUC 0,7767 ± 0,3386). 68 variables, more frequently PET than T2 (0.588 vs 0.412) Seventeen patients (54.8%) were staged ≥ T3, with surgical treatment being contraindicated. Fifteen patients (48.4%) presented with extra-prostatic disease: 8/31 oligometastatic and 7/31 multiple metastasis. Therapy approach following PET/MRI was: radical treatment in 24/31 patients (77.4%): 14 radical prostatectomy and 10 MRI-guided radiotherapy; systemic treatment in 7/31 patients (22.6%). Conclusion18F-Choline PET/MRI had a complementary role for the T staging, with a high detection rate for NM infiltration. PET/MRI findings allowed patients to be directed either to prostatectomy or MRI-guided radiotherapy, and thus avoiding radical treatment in 22.6% of patients.