Fluorine-18 fluorodeoxyglucose imaging using dual-head coincidence positron emission tomography without attenuation correction in patients with head and neck cancer

Purpose: An accurate, preoperative assessment of tumor extent and lymph nod e involvement is necessary to plan and tailor therapy for patients with hea d and neck cancer. Metabolic imaging with fluorine-18 fluorodeoxyglucose (F DG) is a good method to detect primary tumors in the head and neck and to a ssess the involvement of lymph nodes, but it is not widely available becaus e of the high cost of positron emission tomography (PET). Recently, an alte rnative method for using FDG was developed: coincidence detection PET (CoDe PET) using a gamma camera. The aim of this study was to evaluate the clini cal utility of FDG CoDe PET using a gamma camera in patients with head and neck cancer. Materials and Methods: Thirty FDG CoDe PET studies without attenuation correction were pe rformed in seven patients before therapy and in 19 patients after therapy ( ages: 25-79 years, mean, 50 +/- 13 years; 18 men, 8 women) with various hea d and neck cancers. All patients had fasted for 6 to 12 hours and were inje cted with 111 to 370 MBq F-18 FDG 1 hour before imaging. Visually detectabl e focal FDG uptake in the primary tumor site or in the neck was considered positive except for physiologic uptake. The FDG CoDe PET studies were corre lated with MRI. The gold standard for the presence of disease was the combi nation of repeated MRIs, endoscopic examination, and 3 months of follow-up clinical evaluation. Results: FDG CoDe PET had a detection rate that was comparable to that of M RI in the pretherapy group. However, in the posttherapy group, FDG CoDe PET could differentiate residual tumor or tumor recurrence from radiation chan ge more accurately than could MRI. However, it had a less accurate detectio n rate for cervical node metastases because of asymmetric neck muscle uptak e. Conclusions: FDG CoDe PET is a sensitive and cost-effective method to detec t primary tumor and lymph node involvement in primary head and neck cancers . it is also useful in differentiating residual tumor or tumor recurrence f rom posttherapy changes in patients with head and neck tumors.