We evaluated the accuracy of ^18FFDG PET/CT for the detection of recurrence or metastasis after treatment in patients with primary head and neck cancer, and compared the results with those of CT/MRI.

We studied 34 patients with the diagnosis of head and neck cancer, who underwent treatment and follow up with ^18FFDG PET/CT and CT/MRI. The patients were divided into two subgroups based on the difference in follow-up time interval and the type of treatment. Accuracy was evaluated by follow-up information and histopathology findings. The results of the ^18FFDG PET/CT and CT/MRI were compared by statistical analysis.

For the ^18FFDG PET/CT results, 19 FDG uptake lesions were detected in 17 patients. Among these lesions, 18 were confirmed as recurrent or metastatic lesions and one as an inflammatory reaction from radiation therapy. Four lesions that had high FDG uptake were not detected by the CT/MRI. The sensitivity and specificity were 100% and 94.4% for the ^18FFDG PET/CT and 77.8% and 94.4% for the CT/MRI (p<0.05). For the subgroup that received radiation therapy, ^18FFDG PET/CT was more sensitive than CT/MRI (sensitivity = 100% vs. 63.6%, p<0.05).

The results of this study showed that ^18FFDG PET/CT was a useful screening modality for detecting recurrent or metastatic disease after treatment of patients with head and neck cancer, especially post-radiation.