256排CT管电压及重建方式对小内径冠状动脉支架模型显示的影响

Effect of Tube Voltage and Reconstruction Algorithms on the Visualization of Small-diameter Coronary Stents

目的探讨256排CT管电压及重建方式对体外小内径冠状动脉支架显示的影响。材料与方法 256排CT在高清扫描模式下使用不同管电压(70、80、100、120 k Vp)多次扫描2枚小内径体外冠状动脉支架模型(内径分别为2.5 mm和3 mm)。所得图像分别使用高清标准(HD standard)及高清细节(HD detail)重建方式进行重建,对图像质量进行双盲主观评价以及包括支架内CT值、图像噪声、信噪比(SNR)及对比噪声比(CNR)的客观评价,比较各组差异性。结果 2.5 mm及3 mm内径冠状动脉支架均在80 k Vp条件下获得最高主观评分。随着管电压的升高,支架内CT值、SNR及CNR值逐渐降低,各组间差异均有统计学意义(P<0.05)。2.5 mm内径支架HD detail及HD standard两种重建方式的主观评分差异无统计学意义(P>0.05);3 mm内径支架HD detail重建方式主观评分显著高于HD standard,差异有统计学意义(P<0.05)。结论 256排CT高清扫描模式下,80 k Vp联合HD detail重建方式最利于小内径体外冠状动脉支架的显示。

Purpose To evaluate the visibility of in vitro small-diameter coronary stents under different tube voltage and reconstructionalgorithms using 256-detector row CT scanner. Materials and Methods Two coronary-stent models （inside-diameter of 2.5 mm and 3mm） were repeatedly scanned using 256-detector row CT scanner with different tube voltages （70 kVp, 80 kVp, 100 kVp and 120 kVp）under high resolution （HR） mode. Images were reconstructed with HD-detail and HD-standard reconstruction algorithms respectively.Double-blinded subjective evaluation of image quality was performed and objective parameters, including in-stent CT attenuation, noise,signal to noise ratio （SNR） and contrast to noise ratio （CNR）, were also assessed. Results Both 2.5 mm and 3 mm coronary stent hadhighest subjective score at 80 kVp. With the increase of tube voltage, in-stent CT attenuation, SNR and CNR gradually decreased, with significant difference between groups （P〈0.05）. No statistically significant difference was observed in subjective score between HD-detailand HD-standard reconstruction algorithms （P〉0.05） for 2.5 mm stent, while subjective score was significantly higher in HD-detail than HD-standard group for 3 mm stent （P〈0.05）. Conclusion Tube voltage of 80 kVp combined with HD-detail reconstruction algorithm is the optimal way to show small-diameter coronary-stent phantoms under high resolution mode with 256-detector row CT scanner.