POSITRON EMISSION TOMOGRAPHIC IMAGING OF HEAD AND NECK LESIONS

Positron emission tomography (PET) produces images that reflect the ra te and distribution of biochemical and physiological processes in tiss ue in vivo. This has been observed with many types of neoplasm not evi dent when using such anatomical imaging techniques as computed tomogra phy or magnetic resonance imaging. We evaluated the feasibility of 2-F -18-2-deoxy-D-glucose (FDG) PET studies in diagnosing and assessing th e effects of treatment on lesions of the tongue, maxillary sinus and n asopharynx. FDG-PET imaging was performed 45 times in 17 patients with tumors before treatment. Ten patients with malignant lesions also und erwent imaging after treatment. The differential absorption ratio (DAR ) of the isotope was calculated at 55 min and the time activity curve (TAG) was obtained by dynamic emission scans for 0-55 min following in jection of FDG. FDG-PET images, DAR and TAC were evaluated in all lesi ons. Findings showed that FDG-PET images could be used to diagnose mal ignant tumors and evaluate treatment when the DAR was > 4.0 and TAC wa s steep upward. Images suggestive of benign lesions had low DAR values (< 4.0) and mildly upward or flat TACs.