Hyperdense artery sign on computed tomography in acute ischemic stroke

Despite the advent and growing availability of magnetic resonance imaging, the imaging modality of choice in the acute care of stroke patients in many institutions remains computed tomography. The hyperdense artery sign is the earliest marker of acute ischemic stroke. In this short review, we discuss the pathology, incidence, clinical aspects, imaging findings, significance and future questions that need to be addressed concerning this important sign.     

Asymmetry of intracranial internal carotid artery on 3D TOF MR angiography: a sign of unilateral extracranial stenosis

The purpose of this case-control study was to determine whether an asymmetry of size of the intracranial internal carotid artery (ICA) on 3D time-of-flight MR angiography (MRA) is predictive of a high-grade cervical ICA stenosis. Ninety-six stroke/TIA consecutive patients were recruited for the study, of whom 32 had unilateral high-grade ICA stenosis (≥70% NASCET) and were included into the case group, and the remaining 64 did not have such high-grade stenosis and were included in the control group. On intracranial MRA, two observers, blinded to the characteristics of cervical ICA stenosis, independently searched for qualitative size asymmetry between ICAs and measured the cross-sectional surface of the intracranial ICAs. An intracranial size asymmetry was seen in 28 of the 32 high-grade stenoses by both readers, and in 10 (reader₁) and 8 (reader₂) of the 64 controls (sensitivity = 88%, specificity = 84–88%). In patients without agenesia of the A1 segment of the circle of Willis (n = 70), sensitivity was ≥90% and specificity = 96%. Surfaces ratios were significantly different (p < 0.001) between cases and controls. However, using ROC curves analysis, the quantitative processing did not improve the detection when compared with the qualitative assessment of intracranial ICA asymmetry. A size asymmetry of the intracranial ICAs reveals the presence of an underlying high-grade cervical stenosis, with a high degree of confidence, especially in patients without anatomical variant of the anterior part of the circle of Willis. This sign may allow an early detection of high-grade cervical carotid stenosis in stroke patients before dedicated neck imaging is performed.     

3D-TOF MRA单侧颈内动脉假性闭塞原因分析

目的 探讨引起3D-TOF MRA颈内动脉及其分支假性闭塞的原因及表现.方法 实验组:在10例受试者右侧锁骨上1cm颈总动脉搏动处粘贴直径9mm、厚度1.5mm的圆形体小铁片,分别作磁共振平扫、加与不加磁化传递对比(MTC)的横断位3D-TOF MRA,并任选其中两例进行了相位对比法(PC法)MRA检查.病例组:任选10例确诊的单侧大面积脑梗塞病例和1例大动脉炎致右侧颈内动脉闭塞病例,对比分析两组平扫及MRA表现.结果 实验组磁共振平扫正常,无明显伪影;贴铁片后在横断T2 WI上颈内动脉颅内段出现流空效应而呈现低信号;加MTC的3D-TOF MRA中右侧颈内动脉及其分支不显示,PC法两侧颈内动脉及其分支对称显示;去掉MTC的3D-TOF MRA中两侧颈内动脉及其分支对称显示.病例组3D-TOF MRA中右侧颈内动脉及其分支不显示,在横断T2 WI上颈内动脉颅内段出现等、高信号,梗塞病例均出现颅内大面积梗塞病变;大动脉炎病例颅脑磁共振平扫正常,但3D-TOF MRA基地动脉环前后交通支开放,对侧颈内动脉代偿性增粗.结论 颈部的铁磁性异物可引起加MTC的3D-TOF MRA颈内动脉假性闭塞现象,造成误诊,但假性闭塞有其特征性,可通过调整参数排除.     

Agenesis of an internal carotid artery: Angiographic,tomographic and computed tomographic correlation

Summary Congenital absence of one internal carotid artery was found by angiography in a woman of 52 years who had subarachnoid hemorrhage. The absence of the bony carotid canal on the affected side substantiated the congenital nature of this rare vascular anomaly. We believe this to be the first report of absence of the bony carotid canal and the intracavernous portion of the internal carotid artery confirmed by computed tomography and cavernous sinography.     

Post-traumatic aneurysmal dissection of the extracranial internal carotid artery; helical computed tomographic and angiographic aspects: a case]

A 20-year-old man presented with mild intracranial bleeding, a Horner's syndrome, and left neck swelling following head injury. Following noncontrast CT of the brain, a contrast-enhanced helical CT was performed through the neck that showed a hematoma in the poststyloid space (carotid sheath) with irregular diameter of the ICA. Selective digital subtraction angiography confirmed the presence of left cervical ICA dissection with pseudoaneurysm formation. The aneurysm was resected and an end-to-end anastomosis was done using an inverted saphenous graft. Histology confirmed a diagnosis of traumatic ICA dissection with pseudoaneurysm formation and there was no evidence of pre-existing pathology. Helical CT is a simple, widely available, and relatively non-invasive imaging technique that correlates well with angiography. It should be considered in the evaluation of patients with suspected cervical ICA dissection.     

Endovascular recanalization of internal carotid artery occlusion in acute ischemic stroke

BACKGROUND: Endovascular therapy (ET) of internal carotid artery (ICA) stenosis is equivalent to carotid endarterectomy for stroke prevention; however, patients with ICA occlusion and acute symptoms are traditionally not candidates for ET. We report our experience in endovascular recanalization of acute stroke patients with ICA occlusion. PATIENTS AND TECHNIQUES: We reviewed our registry for acute stroke patients treated with ET who had (1) ICA occlusion by digital subtraction angiography (thrombolysis in myocardial ischemia=0) with location of type II (above ophthalmic artery involving M1 or A1 but not both) or type III (proximal to the ophthalmic artery but distal to the bifurcation); (2) acute stroke symptoms from the index lesion presenting 3 hours after onset of symptoms; (3) minimal ischemic changes on brain CT scan (less than one third of the MCA territory); (4) attempted ET. Neuroradiologists reviewed angiograms for thrombolysis in cerebral infarction. A blinded vascular neurologist reviewed post-procedural brain imaging for Alberta Stroke Program Early CT (ASPECT) scoring. Outcome scales were assessed. RESULTS: We identified 14 patients, 10 of whom were men (mean age, 58 +/- 14 years; median age, 54 years; age range, 40-74 years). There were 8 left ICA occlusions, 3 type II; and 6 right ICA occlusions, one type II. Median baseline National Institutes of Health Stroke Scale score was 17 (range, 11-25; mean, 18 +/- 4.9). Mean time to ET was 389 +/- 103 minutes (median, 306 minutes; range, 197-1290 minutes). Immediate recanalization occurred in 64%. Decrease in expected stroke volume by brain imaging occurred in 50% with mean ASPECT score of 4 +/- 2.9 (median, 3; range, 0-8; 21% > or = 8). Two hemorrhages occurred, one symptomatic; 3 patients died. Good outcome was achieved in 64% of cases. CONCLUSION: Endovascular therapy of carotid occlusion in hyperacute stroke patients is feasible and may help to reduce stroke volume and increase good outcome in some patients.     

Malignant middle cerebral artery infarction in hyperacute ischemic stroke: evaluation with multiphasic perfusion computed tomography maps

OBJECTIVE: The purpose of this study was to compare the incidence of large hypoperfusion (greater than two-thirds of MCA territory) on computed tomography (CT) perfusion maps between hyperacute middle cerebral artery (MCA) stroke patients without or with malignant cerebral edema. METHODS: Twenty-seven patients diagnosed with a hyperacute MCA stroke who had an initial National Institutes of Health Stroke Scale (NIHSS) score greater than 10 were included. Multiphasic perfusion CT was performed within 6 hours of symptom onset. Patients were divided into 2 groups: the malignant group (n = 11), composed of patients who died within 7 days, and the nonmalignant group, which included all other patients (n = 16). Unenhanced CT and CT perfusion maps were assessed and compared between the 2 groups with special emphasis on examining the CT findings, including hyperdense MCA sign, large (greater than two-thirds) hypoattenuation and hypoperfusion in the MCA territory, and hypoattenuation in the basal ganglia and other vascular territories. RESULTS: The incidence of large hypoattenuation (greater than two-thirds of MCA territory) on unenhanced CT and large hypoperfusion on CT perfusion maps differed significantly between the 2 groups (P < 0.05). Large hypoperfusion on the CT total perfusion map was most accurate (93%) among various CT findings for the prediction of malignant MCA infarction with high sensitivity (91%), specificity (94%), and positive predictive value (91%). CONCLUSIONS: The incidence of large hypoperfusion on a CT perfusion map was higher in the malignant group than the nonmalignant group. CT perfusion maps may provide added information about cerebral perfusion and could be a useful predictor of malignant MCA infarction.     

Dynamic spin labeling angiography in extracranial carotid artery stenosis

BACKGROUND AND PURPOSE: Similar to digital subtraction angiography, dynamic spin labeling angiography (DSLA) provides time-resolved measurements of the influx of blood into the cerebral vascular tree. We determined whether DSLA may help in assessing the degree of stenosis and whether it provides information about intracerebral collateralization and allows us to monitor the hemodynamic effects of vascular interventions. METHODS: We developed a segmented DSLA sequence that allowed the formation of images representing inflow delays in 41-ms increments. Thirty patients with unilateral carotid artery stenosis and 10 control subjects underwent DSLA. Arrival times of the labeled arterial blood bolus were measured in the carotid siphon (CS) and the middle cerebral artery (MCA) on both sides, and the corresponding side-to-side arrival time differences (ATDs) were calculated. ATDs before and after carotid endarterectomy or percutaneous angioplasty were studied in 10 patients. RESULTS: The degree of stenosis was significantly correlated with ATD in the cerebral vessels. Receiver operating characteristic analysis yielded a cutoff CS ATD of 110 ms to separate stenoses <70% from those > or =70%, with a sensitivity of 90% and a specificity of 67%. In one third of patients, ATD was higher in the MCA than in the CS; this finding suggested an absence of collateralization. Most patients had reduced ATD in the MCA. The degree of ATD reduction was regarded as a quantitative measure of collateralization. Successful intervention resulted in normalized ATDs. CONCLUSION: DSLA is a promising method that allowed us to noninvasively quantify the hemodynamic effect of extracranial carotid stenosis and the resulting intracranial collateralization.     

Duplication of the extracranial internal carotid artery.

We describe a case of duplication of the left internal carotid artery from a point 1 cm distal to the origin to the proximal petrous segment where the vessel reunites. Duplication and fenestration of the internal carotid artery are discussed. A review of embryologic development is presented. Identification of these entities is important, especially in patients who require surgical intervention involving the internal carotid artery.     

MR angiography for the long-term follow-up of dissecting aneurysms of the extracranial internal carotid artery

OBJECTIVE: We used MR angiography to examine and follow up the changes of dissecting aneurysms of the extracranial internal carotid artery (ICA). MATERIALS AND METHODS: We retrospectively reviewed the records of 101 consecutive patients with dissecting aneurysms of the extracranial ICA. Twenty patients with 26 spontaneous dissecting aneurysms were followed up with MR angiography every 1-2 years (men, 16; women, four; age range, 28-67 years; mean age, 51 years). RESULTS: The mean duration of follow-up was 41 months (range, 10-93 months). At MR angiography follow-up, 20 aneurysms did not change, four decreased from their original size by 33-53% (mean, 43%), and two resolved. One patient had an asymptomatic recurrent dissecting aneurysm of the extracranial ICA. Clinically, no patient had a thromboembolic stroke or transient ischemic attack during the follow-up period. CONCLUSION: MR angiography revealed that dissecting aneurysms of the extracranial ICA remain stable, decrease in size, or resolve--but they do not increase in size.     

64排128层螺旋CT血管造影成像技术对颈内动脉粥样硬化狭窄性病变的诊断价值简

目的：探讨64排128层螺旋CT血管造影成像技术（MSCTA）在颈内动脉粥样硬化狭窄性病变诊断中的应用价值。方法回顾性分析行颅颈部CTA检查的31例缺血性脑血管病患者的临床资料,患者全部行颅颈部CTA检查,对其颈动脉成像质量进行评价。结果本组31例缺血性脑血管病患者检查共发现病变血管43支,轻度狭窄20支（46％）,中度狭窄14支（33％）,重度狭窄7支（16％）,闭塞2支（5％）。其中1级可评价血管显示率为87％,2级可评价血管显示率为11％,3级可评价血管显示率为2％。结论64排128层MSCTA可用于颈内动脉粥样硬化狭窄性病变的诊断。     

Vertebrocarotid collateral in extracranial carotid artery occlusions: digital subtraction angiography findings

The internal and external carotid arteries are usually considered occluded distal to a common carotid artery occlusion but some collateral vessels may provide blood keeping the internal and external carotid arteries patent distal to the occlusion. Most common communication in such a case is diversion of blood from muscular branches of the vertebral artery to occipital branch of the external carotid artery which in turn could maintain blood flow into the internal carotid artery, a condition called carotid steal. We encountered vertebrocarotid anastomoses maintaining the patency of carotid circulation in six patients. Patients were four females and two males, ages ranging from 40 to 67 (mean age: 56) years. Five of the patients had ischemic cerebral symptoms. The origin of the external carotid artery was occluded in two and the whole common carotid artery in the remaining four patients. Two patients had double steal, carotid and subclavian at the same time. There was also severe stenosis or occlusion of at least one other major extracranial cerebral artery in all the cases. This concomitant involvement of the second extracranial cerebral artery was thought to be the main reason for the development of vertebrocarotid collateral. In contrast to most of the previously published reports claiming the inadequacy of angiography when compared with colour Doppler ultrasonography, angiography finely depicted the distal patency of the carotid circulation and all the collaterals in detail in every case. Selective injection of the vertebral artery ipsilateral to the occlusion, is the key to demonstrate distal patency of the carotid circulation in cases of proximal carotid occlusion. Demonstration of patency of the distal circulation is very important because some of the patients might get benefit from a reconstructive surgery.     

颅外颈内动脉损伤诊治方法的探讨

目的　探讨颅外颈内动脉损伤的早期诊断和治疗方法。方法　 1982～ 2 0 0 2年共收治颅外颈内动脉损伤 8例 ,其中颈内动脉破裂并休克 3例 ,并发栓塞 4例 ,假性动脉瘤 2例。行颈内动脉修补 2例 ,颈内动脉 -颈外动脉端端吻合 1例 ,颅内 -外动脉搭桥 2例 ,手术取栓 1例 ,瘤体切除加动脉修补 2例。结果无死亡 ,4例出现偏瘫失语等神经系统并发症 ,1例经颅内 -外动脉搭桥后完全康复 ,1例经取栓术后改善 ,2例经保守治疗症状轻度改善。余 4例除 1例遗有颈内动脉假性动脉瘤外 ,均痊愈。结论　早期诊断及颈内动脉修复重建是降低死亡率 ,减少神经系统并发症的关键     

Renal artery mycotic pseudoaneurysm: diagnosis with multi-detector computed tomographic angiography

Renal artery mycotic pseudoaneurysms are uncommon complications of bacterial endocarditis and bacteremia. Complications include hemorrhage and refractory bacteremia, and prompt diagnosis can lead to appropriate treatment. Reported is a case where multi-detector computed tomography angiography led to the correct diagnosis.     

Utility of covered stents for extracranial internal carotid artery stenosis

To our knowledge, the utility of coronary covered stents in the treatment of atherosclerotic carotid artery stenosis has not been defined in the English-language literature. Covered stents may prevent microembolic complications in select atherosclerotic carotid lesions, as they exclude the atherosclerotic lesion from the circulation by pressing the plaque against the vessel wall. Our early clinical experience has shown that use of these stents can be a therapeutic option in select cases of atherosclerotic stenosis of the cervical internal carotid artery.     

DSCTA对颈动脉斑块特征与急性缺血性脑卒中的相关性研究

目的 探讨双源CT血管成像（DSCTA）对颈动脉斑块的诊断价值,评估颈动脉狭窄<50%的斑块特征与急性缺血性脑卒中的关系。方法 选取符合纳入标准患者64例,回顾性分析颈动脉分叉处斑块特征,急性脑卒中侧为实验组,无急性脑卒中侧为对照组。分析内容包括斑块类型、斑块表面形态、钙化分布、钙化数目,对两组颈动脉斑块特征进行统计学分析。结果 实验组颈动脉斑块较对照组更容易出现以下特征且差异有统计学意义,包括非钙化性和混合性斑块出现率更高（Z=-2.39,P=0.02）,斑块表面不规则和溃疡出现率更高（Z=-6.04,P<0.01）,浅层钙化（Z=-2.06,P=0.04）和多发钙化出现率更高（Z=-2.52,P=0.01）。结论 DSCTA可更好的显示斑块特征,颈动脉非钙化性和混合性斑块、斑块表面不规则或溃疡形成、浅层钙化和多发钙化可能为急性缺血性脑卒中的危险因素。     

Doppler spectrum analysis and traditional angiography in the study of the extracranial tract of the internal carotid artery

Examination of 88 extracranial carotid arteries using CW Doppler spectrum analysis is compared with the findings of transfemoral conventional arteriography. There is no significant difference (P greater than 0.05) between CWD and angiographic results, although sensitivity, specificity and accuracy are superior for the latter technique. CWD spectrum analysis can underestimate complete occlusion and misinterpret the degree of stenosis, however it is a cheap and rapid procedure that can be used to judge whether particular symptoms are due to identifiable disease and whether selective carotid arteriography is advisable.     

Rheolytic thrombectomy of the occluded internal carotid artery in the setting of acute ischemic stroke

BACKGROUND AND PURPOSE: Acute thromboembolic stroke complicated by ipsilateral carotid occlusion may present both mechanical and inflow-related barriers to effective intracranial thrombolysis. We sought to review our experience with a novel method of mechanical thrombectomy, in such cases, using the Possis AngioJet system, a rheolytic thrombectomy device. METHODS: A review of our interventional neuroradiology database revealed three patients in whom an occluded cervical internal carotid artery was encountered during endovascular treatment for acute stroke and in whom thrombectomy was attempted, using the 5F Possis AngioJet thrombectomy catheter. The medical records and radiographic studies of these patients were reviewed. RESULTS: Three patients were identified (ages, 52--84 years). Two patients had isolated occlusion of the internal carotid artery; in one patient, thrombus extended down into the common carotid artery. Treatment was initiated within 190 to 360 minutes of stroke onset. Thrombectomy of the carotid artery was deemed necessary because of poor collateral flow to the affected hemisphere (chronic contralateral internal carotid artery occlusion [one patient] and thrombus extending to the carotid "T" [one patient]) or inability to pass a microcatheter through the occluded vessel (one patient). Adjunctive therapy included pharmacologic thrombolysis with tissue plasminogen activator (all patients), carotid angioplasty and stenting (two patients), and middle cerebral artery angioplasty (one patient). Patency of the carotid artery was reestablished in two patients, with some residual thrombus burden. In the third patient, the device was able to create a channel through the column of thrombus, allowing intracranial access. CONCLUSION: Rheolytic thrombectomy shows potential for rapid, large-burden thrombus removal in cases of internal carotid artery thrombosis, allowing expedient access to the intracranial circulation for additional thrombolytic therapy.     

64层螺旋CT颈部动脉成像的临床应用

目的：探讨64层螺旋CT颈部动脉成像技术的临床应用。方法：回顾性分析65例经64层螺旋CT颈部动脉造影检查病例,使用对比剂跟踪技术,后处理使用容积再现技术（VRT）、最大密度投影（MIP）、多平面重建（MPR）、曲面重建（CPR）、仿真内窥镜（CTVE）等技术重建,分析其发育变异、斑块性质、狭窄程度等情况,并结合临床进行分析。结果：65例130条颈动脉中,34条无异常,颈内动脉瘤8条,粥样斑块并狭窄88条。88条狭窄的颈动脉中,轻度狭窄59条（67.0%）,中度狭窄22条（25.0%）,重度狭窄5条（5.7%）,闭塞2（2.3%）条;130条椎动脉中,正常52条,先天性变异27条,粥样斑块并狭窄46条,椎动脉受增生骨质压迫5条。51条狭窄的椎动脉中,轻度狭窄40条（78.4%）,中度狭窄8条（15.7%）,重度狭窄3条（5.9%）。结论：应用64层螺旋CT颈部CTA检查,可同时完成颈动脉与椎动脉血管成像,准确显示血管病变的类型、程度,为临床治疗提供科学的依据。