摘要
目的 研究新一代硅光电倍增管(SiPM)正电子发射断层扫描与X射线计算机断层成像设备(PET/CT)与传统光电倍增管(PMT)PET/CT空间分辨力及图像质量,探讨不同的PET光电转换器(PMT与SiPM)和Q.Clear算法对PET空间分辨力、定量精度和图像质量的影响.方法 分别使用 GE Discovery Elite 型 PET/CT(PMT PET/CT)和 GE Discovery Meaningful Insights(MI)型PET/CT(SiPM PET/CT)对椭圆分辨力模体和NEMA NU2-2018图像质量模体成像.使用OSEM+PSF+TOF(VPFX-S)算法对所有模体原始数据进行图像重建,MI采集的模体数据额外使用Q.Clear算法重建,β取值范围150～550,间隔100.计算分辨力模体中5条线源在3个层面的径向、切向和轴向半高宽(FWHM)并求平均值.计算图像质量模体中小球的恢复系数(RC)、对比度百分比(CRC)、对比噪声比(CNR)、背景变异百分比(PBV)、背景变异系数(BCV)和不同图像层面肺插件残余误差(RE).结果 MI(VPFX-S)与Elite相比,在径向、切向和轴向 FWHM 分别降低 4.25％～13.58％、7.00％～13.22％和 6.02％～36.14％,小球RCmax 无明显差异.MI(VPFX-S)提高小球 CRC(10.17％～38.89％)与 CNR(38.31％～94.95％),降低 PBV(26.20％～33.82％)与 BCV(31.29％～35.97％).MI(Q.Clear)与 MI(VPFX-S)相比,在径向、切向和轴向FWHM分别降低6.49％～45.02％、7.80％～35.60％和13.31％～36.80％,提高小球 CNR(38.31％～94.95％),并降低 PBV(26.20％～33.82％)与BCV(6.64％～10.31％),RC无明显差异.MI(Q.Clear)得到的CNR、RE和径向、切向、轴向FWHM均随β增大而增大,RC、CRC、PBV和BCV均随β增大而减小.结论 在使用VPFX-S重建条件下,与PMT PET/CT相比,新一代SiPM PET/CT在空间分辨力、热灶对比度与探测能力和背景噪声方面均有所提高.相较于O SEM,Q.Clear算法改善了空间分辨力、定量精度与图像质量,但与β的选择有关.β值影响Q.Clear算法带来的收益,对小病灶的最大定量值影响最为明显,这点对提高临床诊断能力尤为重要.
Abstract
Objective To investigate the spatial resolution and image quality of positron emission tomography and X-ray computed tomography(PET/CT)based on the next-generation silicon photomultiplier(SiPM)and the conventional photomultiplier tube(PMT)and to explore the effects of different PET photoelectric transducers(PMT and SiPM)and the Q.Clear algorithm on the spatial resolution,quantitative accuracy,and image quality of PET/CT.Methods GE Discovery Elite PET/CT(PMT PET/CT)and GE Discovery Meaningful Insights(MI)PET/CT(SiPM PET/CT)were employed to scan the elliptical resolution phantom and NEMA NU2-2018 image quality phantom.Using the OSEM+PSF+TOF(VPFX-S)algorithm,image reconstruction was performed based on raw data of both phantoms.For the MI-acquired phantom data,additional reconstructions were conducted using the Q.Clear algorithm,with β values ranging from 150 to 550 and an increment of 100.For the elliptical resolution phantom,the radial,tangential,and axial full-width at half-maximum(FWHM)values of five line sources in three slices were calculated and averaged.For the image quality phantom,the recovery coefficient(RC),contrast recovery coefficient(CRC),contrast-to-noise ratio(CNR),percentage of background variability(PBV),background coefficient of variability(BCV)of the spheres,as well as the residual error(RE)of lung inserts at different image slices,were calculated.Results Compared to Elite,MI(VPFX-S)showed decreases in the radial,tangential,and axial FWHM of 4.25％-13.58％,7.00％-13.22％,and 6.02％-36.14％,respectively;no significant difference in RCmax for the spheres;increases in spheres'CRC and CNR of 10.17％-38.89％and 38.31％-94.95％,respectively,and decreases in spheres'PBV and BCV of 26.20％-33.82％and 31.29％-35.97％,respectively.When compared to MI(VPFX-S),MI(Q.Clear)showed decreases in the radial,tangential,and axial FWHM of 6.49％-45.02％,7.80％-35.60％,and 13.31％-36.80％,respectively;an increase in spheres'CNR of 38.31％-94.95％;decreases in spheres'PBV and BCV of 26.20％-33.82％and 6.64％-10.31％,respectively,and no significant difference in spheres'RC.With an increase in the β value,the CNR,RE,and FWHM in radial,tangential,and axial directions derived from MI(Q.Clear)increased,while RC,CRC,PBV,and BCV decreased.Conclusions Under image reconstruction using VPFX-S,the next-generation SiPM PET/CT exhibits elevated spatial resolution,hot lesion contrast,detectability,and background noise compared to the PMT PET/CT.Compared to OSEM,the Q.Clear algorithm improves spatial resolution,quantitative accuracy,and image quality,with such improvement related to the β value.The β value affects the outcomes of the Q.Clear algorithm,especially the maximum quantitative value of small lesions.This is particularly important for improving clinical diagnostic capabilities.
NETL
NSTL
万方数据