Value of Fused (18)F-Choline-PET/MRI to Evaluate Prostate Cancer Relapse in Patients Showing Biochemical Recurrence after EBRT: Preliminary Results

Purpose. We compared the accuracy of (18)F-Choline-PET/MRI with that of multiparametric MRI (mMRI), (18)F-Choline-PET/CT, (18)F-Fluoride-PET/CT, and contrast-enhanced CT (CeCT) in detecting relapse in patients with suspected relapse of prostate cancer (PC) after external beam radiotherapy (EBRT). We assessed the association between standard uptake value (SUV) and apparent diffusion coefficient (ADC). Methods. We evaluated 21 patients with biochemical relapse after EBRT. Patients underwent (18)F-Choline-PET/contrast-enhanced (Ce)CT, (18)F-Fluoride-PET/CT, and mMRI. Imaging coregistration of PET and mMRI was performed. Results. (18)F-Choline-PET/MRI was positive in 18/21 patients, with a detection rate (DR) of 86%. DRs of (18)F-Choline-PET/CT, CeCT, and mMRI were 76%, 43%, and 81%, respectively. In terms of DR the only significant difference was between (18)F-Choline-PET/MRI and CeCT. On lesion-based analysis, the accuracy of (18)F-Choline-PET/MRI, (18)F-Choline-PET/CT, CeCT, and mMRI was 99%, 95%, 70%, and 85%, respectively. Accuracy, sensitivity, and NPV of (18)F-Choline-PET/MRI were significantly higher than those of both mMRI and CeCT. On whole-body assessment of bone metastases, the sensitivity of (18)F-Choline-PET/CT and (18)F-Fluoride-PET/CT was significantly higher than that of CeCT. Regarding local and lymph node relapse, we found a significant inverse correlation between ADC and SUV-max. Conclusion. (18)F-Choline-PET/MRI is a promising technique in detecting PC relapse.