Abstract

BACKGROUND: Dual head coincidence (DHC) imaging has been proposed as avaluable and cheaper alternative to oncological PET. The increased sensitivity of the recently-developedtriple-headed gamma camera (THC) optimized for coincidence detection has not been either validated orcompared to the sensitivity of a dedicated PET system in a clinical study.Material/Methods: Differencesin contrast-to-noise-ratio (CNR) between dedicated FDG PET, DHC and THC imaging were assessed using ahot sphere phantom. Twenty-two oncological patients were prospectively studied with consecutive wholebody FDG PET and FDG THC imaging. The images were visually read by 2 experienced nuclear medicine specialists.The diagnostic sensitivity of FDG THC imaging was assessed using FDG PET as the imaging gold standard.Lesion size was determined using computed tomography or magnetic resonance imaging.RESULTS: The meangain in CNR for THC as compared to DHC imaging was 35% (10-56%). Of 63 lesions, 58 (92%) on FDG PET werealso detected with THC imaging. Considering only lesions smaller than 15 mm, the relative sensitivitywas 86% (24/29). All lesions above 15 mm (n=34) were detected using THC imaging.CONCLUSIONS: The firstclinical results for THC imaging are promising. The overall relative sensitivity in this limited serieswas 92%. Only a few lesions smaller than 15 mm were missed.

Keywords: Comparative Study, Fluorodeoxyglucose F18, Neoplasms, Tomography, Emission-Computed