Whole-Body [ 18 F]FDG-PET/MRI vs. [ 18 F]FDG-PET/CT in Malignant Melanoma

Purpose To assess the diagnostic performance of simultaneous whole-body 2-deoxy-2-[ 18 F]fluoro-D-glucose ([ 18 F]FDG) positron emission tomography (PET)/magnetic resonance imaging (MRI) compared to [ 18 F]FDG PET/x-ray computed tomography (CT) for detection of distant metastatic disease in patients with malignant melanoma. Procedures We included patients with malignant melanoma who underwent a single injection [ 18 F]FDG dual-imaging protocol that included whole-body PET/CT and subsequent whole-body PET/MRI for staging or restaging purposes in a prospective setting. Images from both modalities were analyzed by two rater teams for the presence of metastatic lesions. PET/CT–PET/MRI overall agreement as well as region-based accuracies, sensitivities (Se), and specificities (Sp) were computed. Results Between July 2014 and December 2018, 22 patients were enrolled. Interrater agreement and overall accuracy (consensus reading) were 78.8 % (95 % CI 71–84.9) and 96.1 % (95 % CI 92.3–98) for PET/MRI and 78 % (70.2–84.3) and 97.4 % (95 % CI 93.7–98.9) for PET/CT, respectively ( P = 0.42). PET/MRI reached a region-based Se of 89.1 % (95 % CI 79.4–94.5) and a Sp of 100 %, whereas PET/CT showed a region-based Se of 92.7 % (95 % CI 84–96.9) and a Sp of 100 % for the detection of metastatic disease in malignant melanoma. Conclusions Whole-body [ 18 F]FDG-PET/MRI appears to be comparable to [ 18 F]FDG-PET/CT for lesion detection in patients with malignant melanoma.