Comparison of thallium-201 and F-18 FDG SPECT uptake in squamous cell carcinoma of the head and neck.

PURPOSE To compare the uptake of 2-[F-18] fluoro-2-deoxy-D-glucose (fludeoxyglucose F-18; F-18 FDG) and thallous chloride Tl 201, using single-photon emission CT (SPECT), for the detection and location of squamous cell carcinoma of the head and neck. METHODS Five patients with biopsy-proved squamous cell carcinoma of the upper aerodigestive tract underwent both F-18 FDG and thallium-201 SPECT on the same day. F-18 FDG SPECT was performed using a dual-head gamma camera equipped with commercially available, extremely high-energy collimators (full width half-maximal height, 17 mm for 511 keV photons). Tumor size was estimated at 1.0 to 5.0 cm3 in these cases. RESULTS F-18 FDG SPECT showed five of five primary tumors. In two of the five cases, normal salivary gland activity severely limited thallium SPECT, and the tumors could not be definitively identified. Two of four lymph node groups that were positive for metastatic disease by CT criteria were shown by F-18 FDG SPECT. None were seen with thallium imaging. In one case, F-18 FDG SPECT was able to show a tumor that was not visible on CT. CONCLUSIONS F-18 FDG has advantages over Tl-201 as a squamous cell carcinoma imaging agent (primarily because of its reduced salivary activity). F-18 FDG SPECT has potential as a viable, less expensive alternative to F-18 FDG positron emission tomography. The ultimate value of F-18 FDG SPECT imaging for detecting occult malignancy, monitoring therapeutic effectiveness, or evaluating tumor recurrence remains to be determined in patients with squamous cell carcinoma of the head and neck.