11C-acetate clearance in nasopharyngeal carcinoma

This study assessed C-11-acetate turnover (clearance) in nasopharyngeal carcinoma (NPC). Data were acquired by dynamic PET after the intravenous injection of 4.625 MBq.kg(-1) body weight of C-11-acetate for 30 min. Tomograms were reconstructed and evaluated visually. A time-activity curve of the nasopharynx and neck was generated and the clearance rate of C-11-acetale from the nasopharynx in the slow phase and from NPC was calculated using 0.693/T-1/2. Ten patients with nasopharyngeal carcinoma and nine normal subjects were studied. The clearance of C-11-acetate from the normal nasopharynx was rapid and biexponential, in contrast to the rapid uptake followed by extremely slow clearance in patients with NPC. The clearance rate (mean +/- S.D.) was 0.0074 +/- 0.0042 in NPC and 0.0263 +/- 0.0152 in controls in the slow phase, being significantly different between the two groups with no overlap. All nasopharyngeal carcinomas were clearly visualized, in contrast to no obvious retention in the normal nasopharynx. Our initial results indicate that C-11-acetate clearance can be used to differentiate nasopharyngeal carcinoma from a normal nasopharynx. This finding may lead to new applications of 11C-acetate in oncology. ((C) 1999 Lippincott Williams & Wilkins).