Impact of Partial Volume Effect on Quantitative Results in SPECT/CT / 中国医学影像学杂志

ABSTRACT

Purpose The partial volume effect is a main factor to impact the image quality and the accuracy of the quantitative analysis of nuclear medicine image.The aim of this study is to evaluate the effects of partial volume effect on quantitative result in SPECT/CT.Materials and Methods A Jaszczak cylindrical phantom and IEC body phantom were performed with routine SPECT/CT imaging using CT attenuation correction,scatter correction and three-dimensional ordered subset expectation maximization (3D-OSEM) reconstruct image.The system volume sensitivity (cpm/kBq) were acquired from the reconstructed image of Jaszczak phantom study.The absolute activity concentration (kBq /ml) of the hot sphere was calculated according to the IEC phantom study that the intensity of radioactivity had been measured in the dose calibrator,then checking computations the quantitative accuracy of all.The difference of quantitative accuracies from the different volume hot sphere was compared tusing a given acquisition and reconstruction parameter.The effects of volume of interest (VOI),target-to-background ratio (TBR) and acquisition time on quantitative accuracy were evaluated.Results CT attenuation correction and scatter correction,the difference of absolute activity and true activity value was obviously correlation with the sphere size by using 3D-OSEM.The quantitative errors were decreased along with the increased of sphere size (r=-0.844,P＜0.05).The quantitative accuracy were significantly affected by the VOI size in the 1.15-11.49 ml sphere.It was obviously lower in the limbic of sphere than that in the center of sphere.And the quantitative errors were decreased along with the decreased of VOI size (r=0.999,0.992,0.994 and 0.767,P＜0.05).However,the quantitative error was no obviously correlation with the VOI size (r=0.348,0.478,P＞0.05) in the 26.52 ml and 0.52 ml sphere.The average quantitative error was lower in high TBR imaging (44.19％) than that in low TBR imaging (-46.18％),and it was lower in 20 s/frame imaging (-44.33％) than that in 10 s/frame imaging (-46.04％).Conclusion The quantitative accurate could be obviously affected by the partial volume effect in SPECT/CT imaging,exceptionally in the small lesions and the limbic of lesions.