OCCULT PRIMARY TUMORS OF THE HEAD AND NECK - DETECTION WITH 2-[F-18]FLUORO-2-DEOXY-D-GLUCOSE SPECT

PURPOSE: To evaluate 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG) sin gle photon emission computed tomography (SPECT) in the detection of cl inically occult primary tumors of the upper aerodigestive tract. MATER IALS AND METHODS: Eighteen patients with histologically proved cervica l nodal metastasis from squamous cell carcinoma (SCC) underwent FDG SP ECT; 17 also underwent computed tomography (CT) and one underwent magn etic resonance (MR) imaging. All 18 patients underwent direct panendos copy and biopsy. Biopsy and imaging results were correlated. RESULTS: Among 11 histologically proved primary tumors, FDG SPECT depicted nine tumors; CT depicted four lesions. Five patients had abnormal FDG upta ke with negative biopsy results. Among five patients with normal SPECT findings, biopsy results were positive in two and negative in three. FDG SPECT at the initial reading had sensitivity of 81%, specificity o f 38%, positive predictive value of 64%, and negative predictive value of 60% for detection of occult primary tumors. CONCLUSION: FDG SPECT guidance of endoscopic biopsies in patients with occult primary SCCs o f the head and neck has the potential to yield a higher rate of positi ve biopsy results than that traditionally expected from ''blind'' endo scopic procedures with ''random'' or ''speculative'' biopsy. FDG SPECT and CT are likely to remain complementary studies for the detection o f occult primary tumors of the head and neck.