摘要
目的通过模拟冠状动脉静态模型分析比较能谱CT宝石能谱成像(GSI)与混合能量成像的图像质量。材料与方法采用模拟冠状动脉静态体模,体模内共3支相同的模拟冠状动脉,管腔内斑块采用人造混合斑块(120 kVp下CT值约60.0～148.6 HU)伴有三种不同程度狭窄(25%、50%及75%)。在3支模拟冠状动脉内分别注入3种不同浓度的对比剂进行扫描,模型内对比剂碘浓度由低到高依次为6.25 mgI/ml、7.89 mgI/ml、14.06 mgI/ml,分别将其定为A、B、C组。采用GE Discovery CT 750 HD扫描仪,采集120 kVp下的混合能量模式(包括混合能量标准扫描和混合能量高清扫描标准重组)及GSI能谱扫描模式;每支模拟冠状动脉分别在每种狭窄处选取4个层面的感兴趣区进行测量,分别测量管腔内CT值、模拟斑块的CT值及背景噪声,计算各层面的对比噪声比(con-trast-to-noise ratio,CNR)。同时由两名专业影像医师根据图像显示情况对感兴趣区的轴位及冠状重组图像进行评分。通过CNR及主观评分的比较评价冠状动脉的图像质量。结果比较GSI序列40～140 keV图像的CNR,A～C组均在50～60 keV具有较好的CNR,比较60 keV单能量图像与混合能量图像不同狭窄率条件下A～C组CNR,除A组浓度25%及75%狭窄率的CNR间比较没有统计学差异,B、C组浓度单能量60 keV扫描模式CNR值均高于混合能量扫描模式,其差异有统计学意义。比较不同狭窄率条件下A～C组图像质量的主观评分,60 keV单能量图像与混合能量图像相比,在对比剂浓度较低时(A组及B组)其评分均高于混合能量图像,其差异有统计学意义,而对比剂浓度相对较高的C组内50%及75%狭窄率的GSI 60 keV单能量图像与混合能量模式图像比较图像质量评分无统计学差异性。结论冠状动脉狭窄模型运用宝石能谱CT扫描,在60 keV时能够获得最佳图像质量,优化图像的CNR,较冠状动脉常规混合能量扫描模式具有更好的图像质量。
Objective To compare the image quality of simulated coronary artery with artificial plaques between gemstone spectral imaging（GSI） and conventional polychromatic X-ray imaging（CPXI）.Materials and MethodsThree microtubes with artificial plaques（the CT value from 60 HU-148.6 HU） injected with three kinds of iodine contrast agent 6.25 mgI/ml（A group）,7.89 mgI/ml（B group）,14.06 mgI/ml（C group） fixed in a water tank received CT（Discovery CT750 HD） scans in order with GSI and CPXI（Scan Type of Segment Standard and Segment High Resolution Standard）,respectively.All GSI data were transferred to AW4.4 workstation to obtain monochromatic images of 60 keV by GSI Viewer.CT values of lumens and plaques and the noise of background were measured at polychromatic images and monochromatic images of 60keV to calculate contrast to noise ratio（CNR）.Meanwhile,the image quality was evaluated by using a four point scale at polychromatic images and monochromatic images of 60 keV.CNR and subject scales between monochromatic images and polychromatic images were compared by two radiologists.ResultsThe optimal monochromatic level for gemstone spectral imaging（GSI） at 60 kev had good contrast to noise ratio compare to polychromatic images of Segment Standard and Segment High Resolution Standard with different stenosis conditions from A～C group,in addition to 25% and 75% stenosis of group A which had no statistically significant.There was significant difference in image quality between monochromatic images and polychromatic images especially with low contrast agent concentration（A and B group）.But there was no significant difference in 50% and 75% stenosis of group C with high contrast agent concentration between monochromatic images and polychromatic images.ConclusionFor plaques in coronary arteries in vitro,GSI could be a good choice to display plaques compared to conventional polychromatic X-ray imaging at 60 kev.
出处
《临床放射学杂志》
CSCD
北大核心
2012年第5期738-742,共5页
Journal of Clinical Radiology
关键词
能谱成像
对比噪声比
单能量成像
冠状动脉
Spectral imaging Contrast-to-noise ratio Monochromatic image Coronary artery
