集成电子探测器联合迭代重建技术不同层厚重建对冠脉支架显示的影响:体外实验研究

Coronary artery stent imaging using an integrated electronics detector and different slice reconstructions: in vitro experience

目的 ：评价联合集成电子探测器与SAFIRE迭代重建技术在不同重建层厚下对不同内径冠脉支架尤其是≤3 mm支架显示的影响。方法：选取不同类型的8枚内径分别为3.5 mm、3 mm以及2.5 mm的支架（编号1~8）,释放于模拟冠脉血管的体外模型中,行配有集成电子探测器的双源CT进行冠脉前瞻扫描,将扫描后得到的原始数据按照不同层厚（0.5 mm、0.6 mm、0.75 mm）进行图像重建分为3组。对上述3组图像进行主客观评价,包括图像质量评分、支架内径差异（Artificial lumen narrowing,ALN）、支架内腔衰减（Attenuation）、图像噪声及衰减噪声比（Attenuation-to-noise ratio,ANR）的评价,统计分析各组间的差异性。结果：图像质量主观评分一致性良好（Kappa=0.797）,0.5 mm重建组获得的图像质量明显高于另两组（P值分别为0.008,0.000）。0.5 mm层厚组ALN值最低,为40.69%±4.16%,与其他各组间均有统计学差异（P值分别为0.043,0.018,P〈0.05）。各组之间,衰减值差异、ANR均未达到统计学意义（P值均〉0.05）。随着重建层厚的增加,图像噪声逐渐降低,但0.5 mm组及0.6 mm组之间图像噪声无明显差异。结论：对于冠脉支架评估,集成电子探测器0.5 mm层厚重建配合SAFIRE迭代重建技术获取的图像质量整体最佳,尤其是对于≤3 mm支架,可为临床提供更佳质量的支架图像。

Objective： To assess the visualization improvement for different coronary stents especially ≤3 mm, using different image slice thickness reconstructed by integrated electronics. Methods： Eight different coronary stents with inner diameter of 3.5 mm, 3 mm and 2.5 mm were placed in plastic tubes filled with contrast agent（iohexol 350 mg I/m L） diluted with saline to make sure that the CT value of contrast was about 350 HU at 120 k Vp. The whole phantom was then settled in an oil tank to mimic the pericardium fatty environment. All the CT scanning data was acquired using Siemens Definition Flash with a in-tegrated electronics detector under prospective coronary CTA mode. Images were reconstructed into 0.5, 0.6 and 0.75 mm slice thickness. Two experienced radiologists blinded to each other evaluated the image quality, image noise, artificial lumen narrow-ing（ALN）, lumial attenuation difference and attenuation-to-noise ratio（ANR）. Results： Among the 3 groups, 0.5 mm images reconstructed were rated best for clearly showing the details of the stents and the inner-lumen situations（Kappa =0.797）. The ALN value of 0.5 mm group was the lowest（40.69%±4.16%）, and was superior to 0.6 and 0.75 mm groups（P=0.043, 0.018, P〈0.05）. But the differences of luminal attenuation and ANR among the three groups were not significant（ P〈0.05）. With the in creasing of the iterative reconstruction slice thickness, the image noise decreased, but the differences between 0.5 mm and 0.6 mm groups were not statistically significant（P〈0.05）. Conclusion： Stent visualization can be benefited from 0.5 mm slice thickness image for more accurate lumen narrowing assessment and lower image noise.