Background: Dual head coincidence (DHC) imaging has been proposed as a valuable and cheaper alternative to oncological PET. The increased sensitivity of the recently-developed triple-headed gamma camera (THC) optimized for coincidence detection has not been either validated or compared to the sensitivity of a dedicated PET system in a clinical study.
Material/methods: Differences in contrast-to-noise-ratio (CNR) between dedicated FDG PET, DHC and THC imaging were assessed using a hot sphere phantom. Twenty-two oncological patients were prospectively studied with consecutive whole body 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 mean gain in CNR for THC as compared to DHC imaging was 35% (10-56%). Of 63 lesions, 58 (92%) on FDG PET were also detected with THC imaging. Considering only lesions smaller than 15 mm, the relative sensitivity was 86% (24/29). All lesions above 15 mm (n=34) were detected using THC imaging.
Conclusions: The first clinical results for THC imaging are promising. The overall relative sensitivity in this limited series was 92%. Only a few lesions smaller than 15 mm were missed.