双层探测器光谱CT冠状动脉成像虚拟单能级图像与常规图像质量比较

Dual-Layer Spectral Detector CT Coronary Angiography: Quality Comparison Between Monochromatic Image and Conventional Image

目的 比较双层探测器光谱CT虚拟单能级冠状动脉血管图像与常规扫描图像的质量,优化冠状动脉的CT图像质量。资料与方法 回顾性分析2021年2—6月于合肥市第二人民医院行双层探测器光谱CT冠状动脉血管成像患者图像100例。以10 keV为间隔,将光谱数据重建出40~150 keV虚拟单能级图像。分别在主动脉根部(AO)、左前降支(LAD)中段、左回旋支(LCX)中段及右冠状动脉(RCA)中段选取感兴趣区,测量冠状动脉的CT值及噪声,比较虚拟单能级图像和常规图像冠状动脉的CT值、信噪比(SNR)、对比噪声比(CNR)和图像噪声,分析LAD、LCX、RCA虚拟单能级图像的SNR、CNR与keV的相关性,以及主观评分一致性。结果 40 keV、50 keV虚拟单能级图像AO、LAD、LCX和RCA的CT值明显高于常规图像(H=723、660、480、641,P<0.01)。图像噪声在40 keV时最大,但与常规图像比较差异无统计学意义(H=5,P>0.05),40~70 keV图像噪声逐渐下降,70 keV之后图像噪声保持稳定(H=192,P<0.01)。LAD、LCX、RCA虚拟单能级图像的SNR、CNR与ke V能级呈负相关(r=-0.864、-0.843、-0.856,-0.816、-0.782、-0.826,P均<0.01),40 keV、50 keV虚拟单能级图像LAD、LCX和RCA的SNR及CNR明显高于常规图像(H=564、489、542、480、551、499,P<0.01)。主观评分显示40 keV、50 keV图像质量明显优于常规图像(H=1 944,P<0.01)。结论 双层探测器光谱CT冠状动脉血管成像,40 keV、50 keV虚拟单能级图像显示冠状动脉图像质量明显高于常规图像。

Purpose To compare the dual-layer spectral detector CT(DLCT) of virtual monochromatic images(VMI) with conventional image(CI) in optimizing the image quality of the coronary computed tomography angiography(CCTA). Materials and Methods A total of 100 patients who underwent CCTA with DLCT in the Second People’s Hospital of Hefei from February to June 2021 were retrospectively analyzed. VMIs were reconstructed from 40-150 keV at interval of 10 keV. The region of interest(ROI) was placed in the aortic root(AO),middle-segment of left anterior descending(LAD), left circumflex(LCX) and right coronary artery(RCA). The CT value and image noise of coronary artery were further measured. The CT value, signal noise ratio(SNR), contrast noise ratio(CNR) and the image noise of VMI and CI were calculated and compared, respectively. The correlation between SNR, CNR and keV of the monochromatic image in LAD, LCX and RCA was analyzed. The subjective score consistency was also observed. Results The CT value of AO, m-LAD, m-LCX, m-RCA of VMIs at 40 and 50 keV were significantly higher than those of CI(H=723, 660, 480, 641, P<0.01). The image noise was the largest at 40 keV, but there was no significant difference in image noise between VMI and CI(H=5, P>0.05). It gradually decreased from 40 to 70 keV, and remained stable after 70 keV(H=192, P<0.01). The SNR and CNR of the monochromatic image of LAD, LCX and RCA were negatively correlated with the keV energy level, respectively(r=-0.864,-0.843,-0.856,-0.816,-0.782,-0.826, all P<0.01). The SNR and CNR of AO, m-LAD, mLCX and m-RCA of VMIs at 40 and 50 keV were significantly higher than those of CI(H=564, 489, 542, 480, 551 and 499, P<0.01). Subjective scores showed that the image quality of VMIs at 40 and 50 keV were significantly better than those of CI(H=1 944, P<0.01). Conclusion The image quality of CCTA of VMI at 40 and 50 keV were significantly higher than those of CI via DLCT.