Neuromaging techniques in cerebrovascular disease: Computed tomography angiography/computed tomography perfusion

Computed tomography angiography (CTA) and computed tomography perfusion (CTP) describe contrast-enhanced techniques, which yield anatomic and functional data about the cerebral vasculature and tissue perfusion. The resulting information helps in the management of patients with cerebrovascular disease (CVD), whether it is chronic atherosclerosis or acute ischemic stroke. CTA and CTP are used to diagnose and grade atherosclerotic disease, to assess the individual patient's risk for development of acute stroke, and in a suspected acute ischemia they help confirm the diagnosis and possibly in stratifying patients for thrombolytic treatment. The information they provide is based on direct evaluation of the major arteries and the perfused lumen, on the morphology of an underlying atheroma, and on the assssment of tissue perfusion and collateral flow.     

Detection of cerebral artery fenestrations by computed tomography angiography

Background and purposeCerebral artery fenestrations (CAF) are rare congenital variations usually diagnosed by digital subtraction angiography (DSA). The aim of this study was to examine the frequency of occurrence of fenestrations in cerebral arteries and their coexistence with cerebral aneurysms in computed tomography angiography (CTA).Material and methodsAll reports of cerebral CTA (1140) performed in one institution from March 2005 to December 2007 were analysed. We found 40 patients with single fenestrations of the intracranial arteries. All 40 examinations were retrospectively reviewed for location of vascular malformations and presence of aneurysms or subarachnoid haemorrhage (SAH). Medical histories of those patients were then analysed for evidence of SAH and referral reasons for CTA.ResultsForty fenestrated arteries were found in CTA: 18 basilar arteries (45%), 16 anterior cerebral arteries (40%), 4 anterior communicating arteries (10%) and one middle cerebral artery (2.5%). Only one vertebral artery fenestration was found due to the technique of the examination. Six patients (15%) with fenestrated arteries had a total of 8 aneurysms, although only one aneurysm was ipsilateral to the fenestration. In 8 cases of SAH, two were with no evidence of vascular malformation. The coexistence of CAF and aneurysms in CTA amounted to 15% (6/40), but the incidence of ipsilateral aneurysm was only 2.5% (1/40) and it affected the anterior cerebral artery.ConclusionsBasilar artery fenestration is the most frequent observed fenestration in CTA, followed by anterior cerebral artery and anterior communicating artery fenestrations. Coexistence of fenestration and aneurysm is uncommon in CTA examination.     

Three-dimensional computed tomography angiography and magnetic resonance angiography of carotid bifurcation stenosis.

PURPOSE: To evaluate the role of computed tomography angiography (CTA) and magnetic resonance angiography (MRA) in the quantification of atherosclerotic stenosis of carotid artery bifurcation in comparison with digital substraction angiography (DSA) and Doppler sonography (DS). MATERIALS AND METHODS: Twenty-five patients with atherosclerotic disease of the carotid arteries with proven stenosis by DSA, had spiral CTA, MRA using two- and three-dimensional time-of-flight gradient echo techniques, and DS using Doppler flow signal recording (total 47 carotid artery bifurcations). The degree of stenosis was measured according to the North American Symptomatic Carotid Endarterectomy Trial criteria: total occlusion (100%), severe (70-99%), moderate (30-69%) and mild (0-29%). The degree of stenosis measured by CTA, MRA and DS was compared to DSA, used as the gold standard. RESULTS: Ninety-seven percent of MRA measures were equivalent to DSA, and 3% were underestimated; 96% of CTA measures were equivalent to DSA, and 4% were underestimated; 77% of DS measures were equivalent to DSA, 21% were overestimated and 2% were underestimated. CONCLUSIONS: CTA and MRA are equally accurate methods in quantifying the degree of carotid bifurcation stenosis.     

Noninvasive angiography (magnetic resonance and computed tomography) in the diagnosis of ischemic cerebrovascular disease. Techniques and clinical applications

Noninvasive diagnostic imaging of the craniocervical and intracranial vasculature is a domain of computed tomography angiography (CTA), magnetic resonance angiography (MRA) and Doppler/duplex ultrasound, the latter not being the topic of this presentation. We give a methodological background for both, CTA and MRA, followed by a critical appraisal of both imaging modalities in the diagnosis of ischemic cerebrovascular disease. The contribution of noninvasive vascular imaging to vascular malformations (including aneurysms, fistulas and cerebral-vein thrombosis) is beyond the scope of this paper and therefore not covered.     

Angiographic findings in relation to clinical course and results of computed tomography in cerebrovascular disease

Clinical course, results of angiography and computerized tomography (CT) were compared in 204 patients with focal cerebral ischemias. The extent and the importance of the radiological results depend on the localization of the affected area, whereby essential differences exist between extra- and intracranial arteries as well as between the vertebrobasilar and the carotid arterial flow region. As to the carotid arterial system there appear to be significant correlations between the size of the infarction on the CT and the extent of the vessel stenosis on angiography. Furthermore the likelihood of deficit recovery is inversely proportional to the degree of pathology seen in both radiologic examinations. It is discussed whether these correlations, obtained from the examination of a great number of patients, can help to evaluate the significance of equivocal angiographic findings in individual cases.     

Ischemic lesion typing on computed tomography perfusion and computed tomography angiography in hyperacute ischemic stroke: a preliminary study

The ability to rapidly and accurately evaluate the location and extent of hyperacute brain ischemia is of major clinical importance. Herein, we aimed to develop imaging criteria to classify the ischemic lesion by computed tomography (CT) perfusion (CTP) and CT angiography (CTA) in hyperacute ischemic stroke patient. Non-contrast-enhanced CT, CTP and CTA were performed in patients with symptoms of hyperacute stroke lasting <8 hours. According to the volume of infarct core, ischemic penumbra and vessel status, three ischemic lesion types were defined. Twenty-six patients were included in our study. Among them, ten patients were classified into severe group, 15 patients were classified into mild group and one patient was classified into reversible group. In acute stroke patients, the ischemic lesion typing may assist in individualizing therapeutic decisions for patients by possibly extending the window for giving thrombolytics beyond the current 3 hour limit.     

计算机断层扫描灌注成像在急性缺血性脑血管病中的应用

计算机断层扫描灌注成像(computerized tomography perfusion, CTP)是利用动态增强计算机断层扫描(CT)和图像后处理技术来反映组织血管化程度和血流灌注状态,从而提供组织器官血流动力学信息的功能成像方法,能一定程度地反映脑缺血病理生理学改变,已成为评价早期脑梗死时组织灌注状态的重要检查手段,与核磁共振(MRI)灌注成像相比,能在最短时间内评估缺血半暗带并指导溶栓治疗.     

Multidetector computed tomography angiography: Application in vertebral artery dissection

Background and Purpose:

Multidetector computed tomography angiography (MDCTA) is a minimally invasive radiological technique providing high-resolution images of the arterial wall and angiographic images of the lumen. We studied the radiological features of vertebral artery dissection (VAD) in a consecutive series of patients investigated for acute stroke and subarachnoid hemorrhage (SAH) in order to confirm and define the diagnostic features of VAD on MDCTA.

Patients and Methods:

Review of patients identified prospectively over a 4-year period with VAD assessed by MDCTA was conducted. Radiological features of VAD on MDCTA were reanalyzed utilising previously reported criteria for VAD.

Results:

Thirty-five patients (25 males, mean age 49.6 years) with a total of 45 dissected vertebral arteries were reviewed. MDCTA features of VAD included increased wall thickness in 44/45 (97.7%) arteries and increased total vessel diameter in 42/45 arteries (93.3%). All dissected arteries had either lumen stenosis (21/45) or associated segmental occlusion (24/45). An intimal flap was detected in 6/45 (13.3 %) vessels. Twenty-five patients had follow-up imaging, 14/32 vessels returned to normal, 4 showed improvement in stenosis but did not return to normal and 14 demonstrated no change. The majority of non-occluded vessels became normal or displayed improved patency. Only 4/17 occluded arteries demonstrated re-establishment of flow. No adverse effects were recorded.

Conclusions:

MDCTA is a safe and reliable technique for the diagnosis of VAD. Increased wall thickness (97.7%) and increased vessel wall diameter (93.3%) were the most frequently observed features.     

术中CT在脑血管疾病手术中的应用

目的 探讨术中CT在脑血管疾病手术中的应用价值.方法 收集2012年3月至8月收治的脑血管疾病患者38例.在手术前后行CT灌注成像(PCT)及CT血管造影(CTA)扫描,根据PCT及CTA情况,指导手术操作.结果 术中扫描总时间19～ 21 min.共行PCT77次、CTA 36次,图像质量良好109次(96.46％),差4次.11例颈动脉狭窄,PCT提示rCBF、rCBV增加,rTTP缩短;CTA提示狭窄消失.25例动脉瘤共处理28个动脉瘤,1例脑灌注异常,调整动脉瘤夹位置后恢复.CT平扫均未见颅内出血.术后随访3～8个月,恢复良好37例(97.4％)、中残1例.结论 术中CT是一种安全、操作简单、成像时间短、能提供高质量图像的技术.术中CT有助于及时发现动脉瘤及脑动静脉畸形残留、载瘤动脉及穿支动脉闭塞,是脑血管疾病外科手术中一种新型辅助技术.     

Assessment of long-term results of intracranial aneurysm clipping by means of computed tomography angiography

Background and purposeThe aim of this retrospective study was to assess the effectiveness of aneurysm clipping by computed tomography angiography (CTA) in a long-term follow-up.Material and methodsThe CTA examination was performed in 119 patients who had 143 aneurysms clipped. The examinations were performed 3 to 11 years (mean 6 years) after clipping using a GE Lightspeed PRO16 scanner.ResultsIn all cases but one, good quality CTA images, suitable for evaluation of the arteries around the clip site, were obtained. Complete aneurysm closure without neck remnant or regrowth was confirmed in 137 (96%) aneurysms. In 4 (3%) cases, neck remnants were detected (2 on the anterior communicating artery [AComA] and 2 on the middle cerebral artery [MCA]). A total clip slippage from the aneurysm dome was revealed in 1 case. One case of aneurysm re-rupture was noted, 11 years after clipping. The rebleeding was caused by AComA aneurysm regrowth. Among these 6 patients with unsatisfactory clipping, 2 required further treatment and 4 remain under observation. Nineteen ‘de novo’ aneurysms in other locations were found in 14 (12%) patients. Summing up all of the pathological findings in the study group, there were 18 (15%) patients who needed further management including close surveillance or re-treatment.ConclusionsComputed tomography angiography is a simple and reliable method of aneurysm clipping evaluation. The long-term follow-up CTA confirmed the permanent and complete obliteration of 96% of the aneurysms. The rate of unsatisfactory aneurysm closure was 4%, but only 1.4% needed re-treatment during a mean follow-up of 6 years. The annual risk of aneurysm re-rupture was 0.1%.     

Prospective evaluation of cerebral angiography and computed tomography in cerebral haematoma.

One hundred and two consecutive patients with cerebral haematoma were prospectively allocated to one of two groups according to their CT on admission. Group 1 patients were thought to have a high probability of an underlying structural lesion and underwent cerebral angiography acutely. If normal, this was repeated at three months. Group 2 patients were thought not to have such a lesion and underwent angiography at three months. Patients older than the mean age of the study population, and hypertensive patients were much less likely to harbour an aneurysm or arteriovenous malformation than younger or normotensive patients (p < 0.01; sensitivity 87.9%, specificity 88.6%). An aneurysm or arteriovenous malformation was the cause of haemorrhage in 12.8% of hypertensive patients, in 30.9% of patients with haematoma involving the basal ganglia, and 18.2% of those with posterior fossa haemorrhage. Features of CT in isolation give a sensitivity of 77.2% and a specificity of 84.2%. Follow up angiography in group 1 showed an arteriovenous malformation in one of seven patients in whom the original study was normal. These results contrast sharply with data from previous retrospective studies. The decision to investigate a patient with cerebral haematoma should be primarily based on the patient's clinical condition, rather than on the site of haemorrhage.     

320排动态容积CT诊断脑血管病的价值

目的探讨320排动态容积cT诊断脑血管病的价值。方法对80例怀疑脑血管病患者行320排动态容积cT检查,经两位有经验的神经影像医师读片,评估其诊断价值。结果80例患者发现颅内血管性病变75例,其中60例为颅内动脉瘤,10例脑动脉硬化,3例脑动静脉畸形,2例烟雾病,5例未发现明确原因。结论320排动态容积CT-次扫描16cm容积数据采集,实现脑血管病cT平扫、脑血管造影及脑灌注一站式检查,具有快速、无创、准确性高等优点,对诊断脑血管疾病具有很高临床价值。     

Diagnostic imaging of cerebrovascular disease on multi-detector row computed tomography (MDCT)

In this study, we reviewed characteristic diagnostic findings of vascular diseases in the central nervous system with 3-dimensional computed tomographic angiography (3D-CTA) using multi-detector row computed tomography (MDCT) and a novel 320-row area detector CT (320-ADCT). With coverage of 160 mm in a single rotation, 320-ADCT enables acquisition of both 4-dimensional CT angiography (dynamic 4D-CTA) and whole-brain CT perfusion imaging. We describe our experience of investigating cerebrovascular diseases with MDCT and 320-ADCT, as well as several postprocessing techniques to acquire images useful for diagnosis, therapy planning, and simulation of neurosurgical and endovascular intervention. 3D-CTA demonstrates has high accuracy in detecting and evaluating cerebral aneurysms and steno-occlusive diseases. Angiographic analysis, including information of surrounding tissues on 3D-CTA, allows assessment of the feasibility of neurosurgical or endovascular approaches and the technique to accomplish the therapy. However, 3D-CTA using MDCT is limited in its detection of aneurysms less than 3 mm in size and aneurysms embedded in the skull base region. In addition, discrimination between intradural paraclinoid aneurysms and extradural intracavernous aneurysms remains an unresolved problem in imaging of cerebral aneurysms. 320-ADCT may solve this problem with its high accuracy in discriminating arteries from the venous system. 3D-CTA could be used as an alternative to DSA for detection of severe carotid artery disease. 3D-CTA enables measurement of the lesions, plaque imaging, prediction of anatomical variants, screening for asymptomatic vascular lesions, and exclusion of patients with risk factors from carotid endoarterectomy (CEA) or carotid artery stenting (CAS). The diagnosis of intracranial dural arteriovenous fistula (DAVF) with CTA is challenging. Recently, several authors proposed diagnostic findings of ADVF by CTA and reported high sensitivity and specificity. 320-ADCT may offer comprehensive information for diagnosis and therapy planning of intracranial DAVF. Although DSA is a standard modality to detect spinal vascular malformations, selective catheterization requires considerable time and a certain amount of contrast medium, and is associated with a risk of neurological complications. Spinal 3D-CTA prior to DSA is useful in selective catheterization to arteries at certain spinal levels as well as when considering treatment options and therapy planning.     

颈内动脉系统频发短暂性脑缺血发作CTA分析

目的探讨颈内动脉系统频发短暂性脑缺血发作(TIA)颈内动脉系统血管狭窄率及特点。方法分析43例颈内动脉系统频发TIA患者的脑CT血管成像(CTA),并与非频发TIA进行对比。结果43例颈内动脉系统频发TIA患者中,有15例(35%)表现为颈内动脉系统颅内动脉狭窄,10例(23%)颅外动脉狭窄,4例(9%)颅内动脉、颅外动脉均有狭窄,14例(33%)无狭窄,狭窄率为67%。轻度、中度、重度狭窄患者分别为7例(16%)、9例(21%)、13例(30%)。33例颈内动脉系统非频发TIA颈内动脉系统血管狭窄率为79%,两组之间无显著性差异(P=0.273)。结论67%的颈内动脉系统频发TIA患者存在颈内动脉系统血管狭窄,但与非频发TIA患者颈内动脉系统狭窄比较无统计学差异。     

64排3D-CTA在脑膜瘤术前评估中的作用

目的探讨64排3D-CTA在脑膜瘤术前评估中的作用。方法脑膜瘤患者29例(嗅沟区2例,桥小脑角区2例,窦旁及镰旁区12例,凸面区2例,蝶骨嵴区10例,鞍结节区1例)。以容积重建法(VR)及最大密度投影法(MIP)等对脑膜瘤及其周围结构做三维重建处理,并做出术前评估。结果本组所有病例3D-CTA图像均可较清楚并立体地显示肿瘤与血管、颅骨及周围结构关系,与手术中所见相吻合。结论64排3D-CTA对脑膜瘤的术前评估、手术入路的设计有独到和重要的意义。     

Preoperative diagnosis and operative effect of intracranial aneurysm with three-dimensional computed tomography angiography

INTRODUCTIONThree-dimensional computed tomography angiography (3D-CTA) is anewimaging diagnosis technique [1]. As compared with Digitalsubtrac-tion angiography (DSA) always regarded as the golden standard for di-agnosis of intracranial aneurysm, its proce…     

Integration of digital angiography, magnetic resonance, x-ray computed tomography and positron emission tomography in stereotaxy

Consecutively to drastic changes which occurred in cerebral imagery techniques, we have developed a stereotactic apparatus and system based on the integration of several new techniques allowing visualisation of the brain: tomodensitometry (TDM), digital subtraction angiography (DSA), magnetic resonance (MR) and positron emission tomography (PET). TDM, DSA and MR can be performed in stereotactic conditions with the apparatus in situ. They give the computer the anatomic references necessary for all calculations. MR and PET images obtained without stereotactic apparatus can also be integrated into the stereotactic study at the condition that DSA was formerly performed in stereotactic conditions, i.e. with the apparatus in situ. The visualisation of the corpus callosum makes this integration possible. An optimal definition of cerebral tumors or target-structures for intracerebral electrode recording is thus obtained.     

Comparing the benefit of ASPECTS on maximum intensity projection images of computed tomography angiography to source images and noncontract computed tomography in predicting infarct volume and collaterals extent

IntroductionIn acute ischemic strokes (AIS), the Alberta Stroke Program Early Computed Tomography Score (ASPECTS) and CT perfusion (CTP) are commonly used to determine mechanical thrombectomy eligibility. Prior work suggests that CTA source image (CTA-SI) ASPECTS (CTA_asp) and a newly described CTA maximum intensity projection (CTA-MIP) ASPECTS (MIP_asp) better predict the final infarct core. Our goal was to compare MIP_asp to CTA_asp and non-contrast CT ASPECTS (NCCT_asp) for predicting ischemic core and collaterals established by CTP.Methods and materialsA single institution, retrospective database for AIS due to internal carotid artery (ICA) or proximal middle cerebral artery (MCA) occlusions between January 2016 and February 2021 was reviewed. We rated ASPECTS on NCCT, CTA-SI, and CTA-MIP at baseline, then used the automated RAPID software to measure CTP ischemic core volume. The accuracy of each ASPECTS in predicting ischemic core volume (ICV) >70 cc and Hypoperfusion intensity ratio (HIR) >0.4 was compared using the receiver operating characteristic (ROC) curve.Results122/319 patients fulfilled the inclusion criteria. Area under the curve (AUC) for MIP_asp was significantly higher than NCCT_asp and CTA_asp for predicting ICV >70 cc (0.95 vs. 0.89 and 0.95 vs. 0.92, P =0.03 and P = 0.04). For predicting HIR >0.4, AUC for MIP_asp was significantly higher than NCCT_asp and CTA_asp (0.85 vs. 0.72 and 0.85 vs. 0.81, P < 0.001 and P < 0.01).ConclusionThe predictive accuracy of detecting ischemic stroke with ICV >70cc and HIR >0.4 can be significantly improved using the MIP_asp instead of CTA_asp or NCCT_asp.