18F-FDG PET/CT and 3.0-T whole-body MRI for the detection of distant metastases and second primary tumours in patients with untreated oropharyngeal/hypopharyngeal carcinoma: a comparative study

Purpose The aim of this prospective study was to compare the diagnostic value of F-18-FDG PET/CT and 3.0-T whole-body MRI (WB-MRI) for the assessment of distant metastases and second primary cancer (SPC) in patients with untreated oropharyngeal or hypopharyngeal squamous cell carcinoma (OHSCC). Methods A total of 103 patients were enrolled. All participants underwent 3.0-T WB-MRI and F-18-FDG PET/CT. The diagnostic capabilities of the two imaging modalities were compared using the area under the receiver-operating-characteristic curve. Histology and follow-up data were used as the reference standard. Results Of the 103 patients, 18 (17.5%) were found to have either distant metastases or SPC. A total of 21 sites were involved. On a lesion-based analysis, F-18-FDG PET/CT showed a trend toward a higher sensitivity than WB-MRI (81.0% vs. 61.9%, P = 0.125). The area under the curve (AUC) for PET/CT was also higher than for WB-MRI, although not significantly so (0.932 vs. 0.866, P = 0.189). On a patient-based analysis, the sensitivity of WB-MRI was lower than that of PET/CT (66.7% vs. 83.3%, P = 0.625). In terms of diagnostic capability, the AUC was higher for PET/CT than WB-MRI (0.886 vs. 0.813, P = 0.355). The maximal SUV of the regional lymph nodes (SUVn) above the median value (8.7 g/ml) was significantly associated with the occurrence of distant metastasis (P = 0.026). Conclusion F-18-FDG PET/CT showed a consistent trend toward higher sensitivity and diagnostic capability than 3.0-Tesla WB-MRI for the detection of distant metastases and SPCs in patients with untreated OHSCC. Our data also suggest that SUVn assessed by PET/CT can provide additional information for the prediction of distant metastases.