Objective: A lack of visualization of the proximal internal carotid artery (ICA) on computed tomography angiography (CTA) in acute ischemic stroke may be caused by an atherosclerotic occlusion or a pseudo-occlusion by a massive thrombus in the ICA. Pseudo-occlusion of the proximal ICA is caused by stagnant flow from a distal ICA occlusion. The purpose of this study aimed to use imaging findings of CTA to differentiate pseudo-occlusion from true occlusions of the proximal ICA.
目的：急性缺血性卒中患者的CT血管造影（CTA）缺乏近端颈内动脉（ICA）的可视化，可能是由于颈内动脉内大量血栓导致动脉粥样硬化闭塞或假性闭塞所致。近端颈内动脉假性闭塞是由远端颈内动脉闭塞引起的血流停滞引起的。本研究的目的是利用CTA的影像学表现来区分近端ICA的假性闭塞和真实闭塞。
Patients and methods: All eligible patients undergoing endovascular treatment after CTA from January 2013 to March 2018 were respectively reviewed. Patients with<2 cm of ICA on CTA images were enrolled in this study. CTA images were classified as having a beak, dome, or flat pattern.
Results: Our sample included a total of 66 eligible patients (true occlusion: 31, pseudo-occlusion: 35). The total length of opacification of the proximal ICA in the pseudo-occlusion group was significantly higher compared to that in the true occlusion group (13.9 ± 4.0 vs. 6.1 ± 4.8, p < 0.001). A beak pattern of the proximal ICA on CTA images was significantly higher in the pseudo-occlusion group (82.9% vs. 16.1%, p < 0.001), but a flat pattern was significantly higher in the true occlusion group (58.1% vs. 0%, p < 0.001). Gradual contrast decline of the proximal ICA on CTA images only appeared in the pseudo-occlusion group (51.4%, p < 0.001).
Conclusions: On CTA, imaging patterns of the proximal ICA can be differentiated between true occlusions and pseudo-occlusions.
患者和方法：分别对2013年1月至2018年3月期间接受CTA血管内治疗的所有合格患者进行回顾性分析。CTA图像上ICA<2 cm的患者被纳入本研究。CTA图像分为鸟喙状、圆顶状或扁平状。
结果：我们的样本共包括66例符合条件的患者（真闭塞：31例，假闭塞：35例）。假性闭塞组近端ICA的总混浊长度明显高于真闭塞组（13.9±4.0 vs.6.1±4.8，p<0.001）。在CTA图像上，近端ICA的喙状模式在假性闭塞组显著高于正常闭塞组（82.9%对16.1%，p<0.001），而扁平状模式在真性闭塞组更常见（58.1%对0%，p<0.001）。近端ICA在CTA图像上的对比度逐渐下降仅出现在假性闭塞组（51.4%，p<0.001）。
结论：在CTA上，近端ICA的成像模式可以区分真实闭塞和假性闭塞。
2.1. Patients
This was a retrospective analysis of single center data on endovascular treatment (EVT) in patients with acute ischemic stroke from January 2013 to March 2018. During this period, 607 patients underwent EVT for recanalization of vessel occlusion of the anterior circulation. Our criteria for EVT were as follows: (1) age ≥ 18 years; (2) initial National Institutes of Health Stroke Scale (NIHSS) score ≥ 4; (3) no evidence of intracerebral hemorrhage detected on non-enhanced CT; (4) obvious major vessel occlusion of the anterior circulation on CT angiography (CTA); (5) infarct core volume less than one-third of the MCA territory on the source image of CTA. Our stroke protocol was as follows: (1) initial non-enhanced CT for evaluation of hemorrhage; (2) CTA with/without perfusion CT for evaluation of vessel occlusion. Of 607 patients, 107 with extracranial internal carotid artery (ICA) occlusion on CT angiography were enrolled in this study.
这是对2013年1月至2018年3月急性缺血性卒中患者血管内治疗（EVT）单中心数据的回顾性分析。在此期间，607名患者接受了EVT，以实现前循环血管闭塞的再通。我们的EVT标准如下：（1）年龄≥ 18年；（2） 美国国立卫生研究院卒中量表（NIHSS）初始评分≥ 4.（3） 未增强CT检查未发现脑出血迹象；（4） CT血管造影（CTA）显示前循环大血管明显闭塞；（5） 在CTA源图像上，梗死核心体积小于MCA区域的三分之一。我们的卒中方案如下：（1）初始非增强CT评估出血；（2） CTA加/不加灌注CT用于评估血管闭塞。在607例患者中，107例在CT血管造影上表现为颅外颈内动脉（ICA）闭塞的患者被纳入本研究。
2.3. Image analysis
We divided the 2 groups based on the angiographic findings of the EVT. Atherosclerotic true ICA occlusion was the complete occlusion by plaque or calcification with no visualization of distal contrast filling above the occlusion segment. Pseudo-occlusion was no contrast filling due to distal ICA or large M1 thrombotic occlusion and no plaque or calcification of the carotid orifice. We excluded patients with contrast filling of the proximal ICA above 2cm because of the bias of pseudo-occlusion.
我们根据EVT的血管造影结果分为两组。动脉粥样硬化性真正ICA闭塞是斑块或钙化的完全闭塞，闭塞段上方未显示远端造影剂填充。假性闭塞是由于颈内动脉远端或M1血栓性闭塞，颈动脉口无斑块或钙化，因此没有造影剂填充。由于伪闭塞的偏差，我们排除了近端ICA造影剂填充超过2cm的患者。
We divided 3 patterns of proximal ICA occlusion on CTA (Fig. 1). A flat pattern was defined as no visualization of proximal ICA contrast filling. A dome pattern was defined as a round shape of the distal portion of the proximal ICA. A beak pattern was defined as a rapid tapering of the proximal ICA. Also, we analyzed the gradual contrast decline of the proximal ICA and the total length of contrast filling of the proximal ICA
我们在CTA上将近端ICA闭塞分为3种类型（图1）。扁平模式被定义为未显示近端ICA造影剂填充。圆顶型被定义为近端ICA远端的圆形。鸟嘴状被定义为近端ICA的快速变细。此外，我们还分析了近端ICA的对比度逐渐下降和近端ICA的对比度填充总长度.图2。
3 Results
Of 107 patients with extracranial ICA occlusion on CT angiography, 41 were excluded because contrast filling of the proximal ICA was above 2cm. Thirty-one patients had atherosclerotic ICA occlusion, and 35 had pseudo-occlusion by contrast stagnation of the proximal ICA due to a massive thrombus of the proximal ICA, distal ICA, or large M1 on cerebral angiography.
107例颅外ICA闭塞的CT血管造影患者中，41例因近端ICA造影剂充盈超过2cm而被排除在外。31例患者有动脉粥样硬化性颈内动脉闭塞，35例患者因脑血管造影上近端颈内动脉、远端颈内动脉或M1的大量血栓导致近端颈内动脉造影剂停滞而出现假性闭塞。
The demographic data and imaging results of proximal ICA occlusion on CTA are shown in Table 1. The beak pattern of the proximal ICA on CTA images was significantly higher in the pseudo-occlusion group (82.9% vs. 16.1%, p < 0.001), but the flat pattern was significantly higher in the true occlusion group (58.1% vs. 0%, p < 0.001) (Figs. 3 and 4).
CTA上近端ICA闭塞的人口统计学数据和成像结果如表1所示。CTA图像上近端ICA的喙状模式在伪闭塞组显著高于正常闭塞组（82.9%vs.16.1%，p<0.001），而平坦模式在正常闭塞组显著高于正常闭塞组（58.1%vs.0%，p<0.001）（图3和图4）。
Gradual contrast decline of the proximal ICA on CTA images only appeared in the pseudo-occlusion group (51.4%, p < 0.000). The gradual contrast decline was not shown in patients with a true occlusion of the proximal ICA. The diagnostic value of each imaging finding using ROC analysis is shown in Table 2. The AUC of the beak pattern for diagnosis of a pseudo-occlusion of the proximal ICA was the highest at 0.834. The AUC of the flat pattern for diagnosis of a true occlusion was the highest at 0.790. The total length of contrast filling of the proximal ICA in the pseudo-occlusion group was significantly higher compared to that in the true occlusion group (13.9 ± 4.0 vs. 6.1 ± 4.8, p < 0.001).
近端ICA在CTA图像上的对比度逐渐下降仅出现在假性闭塞组（51.4%，p<0.000）。在近端ICA真正闭塞的患者中，对比度没有逐渐下降。表2显示了使用ROC分析的每个成像发现的诊断价值。诊断近端颈内动脉假性闭塞的喙型AUC最高，为0.834。平坦模式诊断真闭塞的AUC最高，为0.790。假性闭塞组近端ICA造影剂充盈的总长度明显高于真闭塞组（13.9±4.0 vs.6.1±4.8，p<0.001）。
Fig. 4. Examples of three patterns of proximal ICA occlusion on CT angiography.
A and B. CTA of a 57-year old man with right hemiplegia shows the beak pattern of proximal ICA occlusion on CTA (A). Cerebral angiography shows the complete
thrombotic occlusion of petrous ICA (B).
C and D. CTA of a 54-year old man with left hemiplegia shows the dome pattern of proximal ICA occlusion (C). Cerebral angiography shows the thrombotic occlusion
of ICA terminus (D).
E and F. CTA of a 73-year old man with left hemiplegia shows the flat pattern of proximal ICA occlusion (E). Cerebral angiography shows the complete occlusion with
plaque (F). He underwent the carotid stent and endovascular treatment about MCA occlusion.
Clin Neurol Neurosurg.2019；Oct;185:105495.doi: 10.1016/j.clineuro.2019.105495.
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