Annals of Nuclear Medicine 2000 August;Vol.14 No.4:279-284

Fundamental study of hot spot detectability in 3-dimensional positron emission tomography

Hong ZHANG, Tomio INOUE, Saleh ALYAFEI, Mei TIAN, Noboru ORIUCHI, Akihiro ICHIKAWA, Kunio MATSUBARA and Keigo ENDO

Department of Diagnostic Radiology and Nuclear Medicine, Gunma University School of Medicine, Gunma, Japan

The purpose of this study was to investigate the detectability of small hot lesions with the 3-dimensional transmission/emission (3D T/E) acquisition mode in FDG-PET scan. The correlation of target detectability, target size, target to non-target uptake ratio (T/N ratio) and standardized uptake value(SUV) were studied. Small hot lesions ranged from 4.4 mm to 36.9 mm in diameter were located in a cylindrical phantom. The images of phantoms with a T/N ratio of 2.0, 4.0, 6.0, 8.0, 9.6, 13.2, 17.5, 23.8 and 30.3 were obtained with 2- dimensional transmission/emission (2D T/E) scan and 3D T/E scans. Targets in diameter more than 10.6 mm in diameter with an actual T/N ratio ranged from 6.0 to 30.3 could be identified on the images obtained with both the 2D T/E and 3D T/E acquisition modes. The detectability efficiency of small hot targets with 2D T/E and 3D T/E scans was the same (77.8%). The T/N ratio of targets from 2D T/E images was 30% to 48.4% different to that from the 3D T/E image, and the SUV of the target from the 2D T/E image was almost the same as that from the 3D T/E images. This study revealed that 3D T/E scanning had similar hot spot detectability to 2D T/E scanning; 3D T/E and 2D T/E scanning had the same faculty for semi-quantitative.