Qualitative and Quantitative Performance of18F-FDG-PET/MRI versus18F-FDG-PET/CT in Patients with Head and Neck Cancer

BACKGROUND AND PURPOSE: MR imaging and PET/CT are integrated in the work-up of head and neck cancer patients. The hybrid imaging technology 18 F-FDG-PET/MR imaging combining morphological and functional information might be attractive in this patient population. The aim of the study was to compare whole-body 18 F-FDG-PET/MR imaging and 18 F-FDG-PET/CT in patients with head and neck cancer, both qualitatively in terms of lymph node and distant metastases detection and quantitatively in terms of standardized uptake values measured in 18 F-FDG-avid lesions. MATERIALS AND METHODS: Fourteen patients with head and neck cancer underwent both whole-body PET/CT and PET/MR imaging after a single injection of 18 F-FDG. Two groups of readers counted the number of lesions on PET/CT and PET/MR imaging scans. A consensus reading was performed in those cases in which the groups disagreed. Quantitative standardized uptake value measurements were performed by placing spheric ROIs over the lesions in 3 different planes. Weighted and unweighted κ statistics, correlation analysis, and the Wilcoxon signed rank test were used for statistical analysis. RESULTS: κ statistics for the number of head and neck lesion lesions counted (pooled across regions) revealed interreader agreement between groups 1 and 2 of 0.47 and 0.56, respectively. Intrareader agreement was 0.67 and 0.63. The consensus reading provided an intrareader agreement of 0.63. For the presence or absence of metastasis, interreader agreement was 0.85 and 0.70. The consensus reading provided an intrareader agreement of 0.72. The correlations between the maximum standardized uptake value in 18 F-FDG-PET/MR imaging and 18 F-FDG-PET/CT for primary tumors and lymph node and metastatic lesions were very high (Spearman r = 1.00, 0.93, and 0.92, respectively). CONCLUSIONS: In patients with head and neck cancer, 18 F-FDG-PET/MR imaging and 18 F-FDG-PET/CT provide comparable results in the detection of lymph node and distant metastases. Standardized uptake values derived from 18 F-FDG-PET/MR imaging can be used reliably in this patient population.