Investigation of 18F-FDG 3D mode PET image quality versus acquisition time

ObjectiveThree-dimensional (3D) mode positron emission tomography (PET) is being used increasingly for clinical PET imaging. However, as yet, optimal acquisition parameters have not been established. The aim of this study was to investigate the effect of varying acquisition time on 3D image quality using standard clinical activities of 18F-fluorodeoxyglucose (FDG). Methods18F-FDG phantom and patient PET images were acquired with varying acquisition times on a GE Discovery-STE PET/CT system. The NEMA Image-Quality phantom was imaged with four hot lesions in a uniform background. Images were acquired for 1, 2, 3, 4, and 5-min frames with three different lesion-to-background contrast ratios. Patient data were investigated using list mode acquisition to obtain comparable 2, 3, and 4-min frames. Qualitative analysis involved grading image quality and lesion detectability. Quantitative analysis of phantom images involved assessing the coefficient of variation (COV) of background areas as a measure of noise, and lesion over background variability as a measure of image quality. Patient data were also assessed using COV analysis of liver uptake. ResultsQualitative and quantitative analysis showed no significant difference in image quality between 4 and 5-min acquisition frames for 3D mode 18F-FDG PET imaging with standard clinical activities. The observers noted no difference in perceived image quality. This finding was supported by COV analysis. ConclusionThis study shows that GE Discovery-STE acquisition frame time can be reduced to 3 min for standard 3D mode imaging at standard clinical activities of 18F-FDG.