双层探测器光谱CT在优化髂动脉及其次级分支图像质量中的应用

Application of Double-layer Detector Spectral CT in Optimizing the Iliac Artery and Its Secondary

目的:探讨双层探测器光谱CT单能量成像对髂动脉及其次级分支图像质量的影响。方法:回顾性分析43例在苏州永鼎医院行下腹部增强的患者图像,所有患者均在飞利浦双层探测器光谱CT上进行下腹部增强检查,将所有患者图像动脉期传送至飞利浦星云工作站(Philips IntelliSpace Portal,ISP),利用ISP将动脉期图像重建出40keV、50keV、60keV、70keV、80keV单能量组和常规混合能量组6组图像,测量并比较六组图像髂动脉CT值、噪声(SD)、信噪比(SNR)、对比噪声比(CNR)的差异,并以5分法对髂动脉及其分支进行主观评分加以记录。结果:六组髂动脉的CT值、SD、SNR、CNR差异均有统计学意义(P<0.05),其中40keV组的CT值、SNR和CNR显著高于其他单能量和常规组(P<0.01),70keV与常规组相比,CT值、SNR和CNR无统计学差异(P=0.429,P>0.999,P>0.999),40keV组的噪声显著低于常规组(P<0.01)。两位医师对常规图像组、40keV、50keV、60keV、70keV、80keV的图像质量评价一致性较好(Kappa=0.853、0.846、0.819、0.768、0.733),且两位医师对40keV图像主观评分最优(P<0.05)。结论:40keV为显示髂动脉的最佳单能量,70keV图像质量接近常规混合能量组图像,40keV在不增加图像噪声的情况下,可以显著增加髂动脉的CT值,提高髂动脉及其分支的显示能力。

Objective:To investigate the effect of double-layer detector spectral CT single-energy imaging on the image quality of the iliac artery and its secondary branches.Methods:A retrospective analysis was made on the images of 43 patients who underwent lower abdominal enhancement in Suzhou Yongding hospital.All patients underwent enhanced examination of the lower abdomen on Philips dual-detector spectral CT,and the obtained images in the arterial phase were transmitted to the Philips IntelliSpace Portal(ISP).Six groups of images of 40 keV,50 kev,60 keV,70 kev and 80 kev single energy group and conventional mixed energy group were reconstructed by ISP.The differences of CT value,noise(SD),signal-to-noise ratio(SNR) and contrast noise ratio(CNR) of iliac artery in the six groups were measured and compared,and the subjective scores of iliac artery and its branches were recorded by 5-devided method.Results:There were significant differences in CT value,SD,SNR and CNR of iliac artery among the six groups(P0.999,P>0.999) compared with the conventional group at 70 keV;and the noise in the 40 keV group was significantly lower than that in the conventional group(P<0.01).The two doctors evaluated the image quality of conventional image group,40 keV,50 kev,60 keV,70 kev and 80 kev with good consistency(kappa = 0.853,0.846,0.819,0.768 and 0.733),and they had the best subjective scores for 40 keV images(P<0.05).Conclusion:40 keV is the best single energy to display the iliac artery,and the image quality of 70 keV is close to the conventional mixed energy group image.Without increasing image noise,40 keV can significantly increase the CT value of the iliac artery and improve the display ability of the iliac artery and its branches.