PET/CT and 3-T whole-body MRI in the detection of malignancy in treated oropharyngeal and hypopharyngeal carcinoma.

Purpose: We performed a prospective comparison of the diagnostic capability of integrated fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) (PET/CT), 3-T whole-body magnetic resonance imaging (WB-MRI) and their combination in detecting malignancy in treated oropharyngeal or hypopharyngeal squamous cell carcinoma (OHSCC).

Methods: Seventy-nine OHSCC patients at a high risk of residual disease or suspected to have recurrence after the completion of chemoradiation were included in the study. All patients underwent PET/CT and WB-MRI within 10 days of each other. Histology and follow-up data were used as the reference standard. The McNemar test was used to compare sensitivity and specificity, while the area under the receiver-operating characteristic curve (AUC) was used for comparison of diagnostic capabilities.

Results: Twenty-nine patients (36.7%) had residual/recurrent tumours or second primary tumours. Overall, there was a trend towards increased sensitivity and diagnostic capability for PET/CT compared with WB-MRI (72.4 vs 55.2%, p = 0.13; 0.826 vs 0.753, p = 0.24, respectively). The diagnostic capability of combined interpretation of PET/CT and WB-MRI was similar to PET/CT alone (0.827 vs 0.826, p = 0.97) but was significantly higher than WB-MRI alone (0.827 vs 0.753, p = 0.04).

Conclusion: PET/CT showed a trend towards higher diagnostic capability than 3-T WB-MRI in detecting residual/recurrent tumours or second primary tumours in OHSCC. The combined use of PET/CT and WB-MRI provided more added value to WB-MRI alone than to PET/CT alone. Additional PET/CT can be useful in patients with questionable MRI findings of malignancy.