F-18-FDG Imaging Using Dual-Head Coincidence Positron Emission Tomography in Patients with Head and Neck Cancer

Abstract

BACKGROUND AND OBJECTIVES: An accurate, preoperative assessment of tumor extent and lymph node involvement is necessary to plan and tailor therapy for patients with head and neck cancer. Metabolic imaging with tluorine-18-fluorodeoxyglucose (FDG) is a good method to detect primary cancers in the head and neck and to assess the involvement of lymph nodes, but it is not widely available because of high cost of positron emission tomography (PET). Recently, an alternative method for using FDG was developed: the coincidence detection PET (CoDe PET) using a gamma camera. The aim of this study was to evaluate the clinical utility of FDG CoDe PET using a gamma camera in patients with head and neck cancer. MATERIALS AND METHODS: Thirty FDG CoDe PET studies were performed in 7 patients before therapy and 19 patients after therapy with various head and neck cancers (Age : 25- 79 years, mean age : 50+/-13 years, 18 men, 8 women). All patients had fasted for 6 to 12 hours and were injected 1 1 l to 370 MRq of F-18-FDG 1 hour before imaging. With the exception of the physiological FDG uptake, all visually detectable focal FDC uptake in the primary cancer site or in the neck was considered positive. FDG CoDe PET studies were correlated with CT/MRI. The standard procedure for detecting the presence of disease was the combinations of repeated MRIs, 3 months of follow-up clinical evaluation and the result of a needle aspiration cytology or biopsy. RESULTS: FDG CoDe PET had a detcction rate that was comparable to that of CT/MRI in the pre-therapy group. However, in the post-therapy group, FDG CoDe PET could differentiate residual/recurrence of tumor from radiation change more accurately than could MRI. But, it had a less accurate detection rate for cervical metastases because of asymmetric neck muscle uptake. CONCLUSION: FDG CoDe PET is a sensitive and cost-effective method to detect primary tumor and lymph node involvement in primary head and neck cancers. It is also useful in differentiating residual tumor or tumor recurrence from post-therapy changes in patients with head and neck cancers.