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) single photon emission computed tomography (SPECT) in the detection of clinically occult primary tumors of the upper aerodigestive tract. MATERIALS AND METHODS: Eighteen patients with histologically proved cervical nodal metastasis from squamous cell carcinoma (SCC) underwent FDG SPECT; 17 also underwent computed tomography (CT) and one underwent magnetic resonance (MR) imaging. All 18 patients underwent direct panendoscopy 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 uptake 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 of 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 of the head and neck has the potential to yield a higher rate of positive biopsy results than that traditionally expected from ''blind'' endoscopic procedures with ''random'' or ''speculative'' biopsy. FDG SPECT and CT are likely to remain complementary studies for the detection of occult primary tumors of the head and neck.