Comparison of image quality between step-and-shoot and continuous bed motion techniques in whole-body 18F-fluorodeoxyglucose positron emission tomography with the same acquisition duration.

Abstract

This study aimed to compare the qualities of whole-body positron emission tomography (PET) images acquired by the step-and-shoot (SS) and continuous bed motion (CBM) techniques with approximately the same acquisition duration, through phantom and clinical studies. A body phantom with 10-37mm spheres was filled with 18F-fluorodeoxyglucose (FDG) solution at a sphere-to-background radioactivity ratio of 4:1 and acquired by both techniques. Reconstructed images were evaluated by visual assessment, percentages of contrast (%Q H) and background variability (%N) in accordance with the Japanese guideline for oncology FDG-PET/computed tomography (CT). To evaluate the variability of the standardized uptake value (SUV), the coefficient of variation (CV) for both maximum SUV and peak SUV was examined. Both the SUV values were additionally compared with those of standard images acquired for 30min, and their accuracy was evaluated by the %difference (%Diff). In the clinical study, whole-body 18F-FDG PET/CT images of 60 patients acquired by both techniques were compared for liver signal-to-noise ratio (SNRliver), CV at end planes, and both SUV values. In the phantom study, the visual assessment and %Q H values of the two techniques did not differ from each other. However, the %N values of the CBM technique were significantly higher than those of the SS technique. Additionally, the CV and %Diff for both SUV values in the CBM images tended to be slightly higher than those in SS images. In the clinical study, the SNRliver values of CBM images were significantly lower than those of SS images, although the CV at the end planes in CBM images was significantly lower than those in SS images. In the Bland-Altman analysis for both SUV values, the mean differences were close to 0, and most lesions exhibited SUVs within the limits of agreement. The CBM technique exhibited slightly lesser uniformity in the center plane than the SS technique. Additionally, in the phantom study, the CV and %Diff of SUV values in CBM images tended to be slightly higher than those of SS images. However, since these differences were subtle, they might be negligible in clinical settings.