Blum Melanie B, Schmook Maria, Schernthaner Rüdiger, Edelhauser Gundula, Puchner Stefan, Lammer Johannes, Funovics Martin A
Division of Angiography and Interventional Radiology, Department of Radiology, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria.
AJR Am J Roentgenol. 2007 Nov;189(5):1238-42. doi: 10.2214/AJR.07.2501.
The purpose of this study was to compare CT angiography (CTA) and MR angiography (MRA) for the detectability of 75% and 95% stenoses in phantoms using six different stents.
Six different stents (Expander, Hemobahn, SelfX, Smart, Symphony, and Wallstent) were inserted into tubes filled with contrast agent (ioversol or gadoteric acid). To mimic stenoses of 75% and 95% of the patent lumen, 8-mm-diameter nylon cylinders were bored in the central axis (2 mm and 4 mm, respectively) and placed into the stent lumen. Intensity profiles across stenoses on 2-mm coronal reformatted sections of CTA or MRA were compared, and the detectability of the residual lumen was assessed using a subjective score.
CTA showed relative in-stent signal attenuation for the in-stent stenoses of the tested stents ranging from 75% to 100% of the signal intensity of the control. SelfX and Symphony showed further shading of the residual lumen due to beam-hardening artifacts. Overestimation of stenosis was associated with low-grade stenoses in which the border of the lumen was closer to the stent struts. MRA showed relative in-stent signal attenuation of the in-stent stenoses ranging from 30% to 100% of the signal intensity of the control. Strut thickness tended to correlate with higher attenuation at CT.
CTA may be more suitable for differentiation between 95% stenosis and occlusion; MRA has higher sensitivity in detecting 75% stenoses. Strut thickness and mesh size did not prove to be significant predictors for signal attenuation or overall image quality.
本研究的目的是比较CT血管造影（CTA）和磁共振血管造影（MRA）在使用六种不同支架的体模中检测75%和95%狭窄的能力。
将六种不同的支架（扩张器、Hemobahn、SelfX、Smart、Symphony和Wallstent）插入充满造影剂（碘海醇或钆特酸）的管中。为模拟管腔75%和95%的狭窄，在中心轴上钻出直径8毫米的尼龙圆柱体（分别为2毫米和4毫米），并放入支架管腔中。比较CTA或MRA 2毫米冠状位重组图像上狭窄部位的强度曲线，并使用主观评分评估残余管腔的可检测性。
CTA显示，测试支架的支架内狭窄部位的支架内信号衰减相对于对照信号强度为75%至100%。SelfX和Symphony由于束硬化伪影，残余管腔进一步变暗。狭窄的高估与低级别狭窄有关，其中管腔边界更靠近支架支柱。MRA显示，支架内狭窄部位的支架内信号衰减相对于对照信号强度为30%至100%。在CT上，支柱厚度往往与更高的衰减相关。
CTA可能更适合区分95%的狭窄和闭塞；MRA在检测75%狭窄方面具有更高的灵敏度。支柱厚度和网眼尺寸并未被证明是信号衰减或整体图像质量的重要预测因素。
