Diagnostic value of retrospectively fused 64CuCl2 PET/MRI in biochemical relapse of prostate cancer: comparison with fused 18F-Choline PET/MRI, 64CuCl2 PET/CT, 18F-Choline PET/CT, and mpMRI.

PURPOSE To assess the diagnostic value of retrospectively fused PET/MRI by comparing the detection rates (DRs) of fused 64CuCl2 PET/MRI vs. fused 18F-Choline PET/MRI in patients with suspected prostatic cancer (PCa) recurrence. The secondary objective was to compare the DRs of fused PET/MRI vs. those of the separate imaging modalities. METHODS We retrospectively evaluated 50 PCa patients with biochemical relapse after radical prostatectomy (RP) or radiotherapy (RT). All patients underwent 64CuCl2 PET/CT, 18F-Choline PET/CT, and multiparametric magnetic resonance imaging (mpMRI) within 15 days. Fused 64CuCl2-PET/MRI and fused 18F-Choline PET/MRI images were obtained by retrospective co-registration of MRI and PET images. Experienced readers interpreted the images, and the DRs of each imaging modality were assessed. RESULTS In the patient-based analysis, overall DRs of fused 64CuCl2 PET/MRI, fused 18F-Choline PET/MRI, 64CuCl2 PET/CT, 18F-Choline PET/CT, and mpMRI were 88%, 68%, 82%, 56%, and 74%, respectively. In the lesion-based analysis, overall DRs of fused 64CuCl2 PET/MRI, fused 18F-Choline PET/MRI, 64CuCl2 PET/CT, 18 F-Choline PET/CT, and mpMRI were 95%, 66%, 87%, 58%, and 71%, respectively. CONCLUSIONS Retrospectively fused PET/MRI is able to overcome the limitations of the separate interpretation of the individual imaging modalities. Fused 64CuCl2 PET/MRI provided the highest diagnostic performance in the detection of PCa local relapse.