Initial clinical results of simultaneous 18F-FDG PET/MRI in comparison to 18F-FDG PET/CT in patients with head and neck cancer

Purpose The aim of this study was to evaluate the diagnostic capability of simultaneous F-18-fluorodeoxyglucose (FDG) positron emission tomography (PET)/MRI compared to F-18-FDG PET/CT as well as their single components in head and neck cancer patients. Methods In a prospective study 17 patients underwent F-18-FDG PET/CT for staging or follow-up and an additional F-18-FDG PET/MRI scan with whole-body imaging and dedicated examination of the neck. MRI, CT and PET images as well as PET/MRI and PET/CT examinations were evaluated independently and in a blinded fashion by two reader groups. Results were compared with the reference standard (final diagnosis determined in consensus using all available data including histology and follow-up). Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated. Results A total of 23 malignant tumours were found with the reference standard. PET/CT showed a sensitivity of 82.7%, a specificity of 87.3%, a PPV of 73.2%and a NPV of 92.4%. Corresponding values for PET/MRI were 80.5, 88.2, 75.6 and 92.5%. No statistically significant difference in diagnostic capability could be found between PET/CT and PET/MRI. Evaluation of the PET part from PET/CT revealed highest sensitivity of 95.7%, and MRI showed best specificity of 96.4%. There was a high inter-rater agreement in all modalities (Cohen's kappa 0.61-0.82). Conclusion PET/MRI of patients with head and neck cancer yielded good diagnostic capability, similar to PET/CT. Further studies on larger cohorts to prove these first results seem justified.