颈动脉增强对评价颈动脉斑块稳定性的作用

目的:通过分析颈动脉粥样硬化(AS)血管壁的强化特征,评价血管壁强化程度与斑块稳定性之间的关系.方法:148例临床疑为颈部血管狭窄的患者中61例行CTA、87例行CE-MRA检查,分析斑块的类型并测量邻近血管壁的强化程度以及管腔狭窄程度,评价管壁强化特征与斑块稳定性之间的关系.CTA组部分患者与DSA对照.结果:CTA组:狭窄血管74支,轻度狭窄34支,中度狭窄24支,重度狭窄19支,3支完全闭塞;软斑块32块,硬斑块25块,溃疡斑6块,软斑块处血管壁强化明显高于硬斑块,部分患者与DSA比较,二种检查方法对血管狭窄的显示无显著性差异.CE-MRA组:狭窄血管79支,轻度狭窄28支,中度狭窄33支,重度狭窄13支,5支完全闭塞;软斑块28块,硬斑块49块,血栓2块,软斑块处血管壁强化明显高于硬斑块.结论:CTA和CE-MRA在评价颈动脉粥样硬化斑块的稳定性方面各有优势,能够为临床预测缺血性脑卒中提供非常可靠准确的信息.     

3D-Arterial analysis software and CEUS in the assessment of severity and vulnerability of carotid atherosclerotic plaque: a comparison with CTA and histopathology

Purpose

Our purpose is to assess Multiparametric Ultrasound (MPUS) efficacy for evaluation of carotid plaque vulnerability and carotid stenosis degree in comparison with Computed Tomography angiography (CTA) and histology.

Material and methods

3D-Arterial Analysis is a 3D ultrasound software that automatically provides the degree of carotid stenosis and a colorimetric map of carotid plaque vulnerability.

We enrolled 106 patients who were candidates for carotid endarterectomy. Prior to undergoing surgery, all carotid artery plaques were evaluated with Color-Doppler-US (CDUS), Contrast-Enhanced Ultrasound (CEUS), and 3D Arterial analysis (3DAA) US along with Computerized Tomographic Angiography (CTA) to assess the carotid artery stenosis degree. Post-surgery, the carotid specimens were fixed with 10% neutral buffered formalin solution, embedded in paraffin and used for light microscopic examination to assess plaque vulnerability morphological features.

Results

The results of the CTA examinations revealed 91 patients with severe carotid stenoses with a resultant diagnostic accuracy of 82.3% for CDUS, 94.5% for CEUS, 98.4% for 3DAA, respectively. The histopathological examination showed 71 vulnerable plaques with diagnostic accuracy values of 85.8% for CDUS, 93.4% for CEUS, 90.3% for 3DAA, 92% for CTA, respectively.

Conclusions

The combination of CEUS and 3D Arterial Analysis may provide a powerful new clinical tool to identify and stratify “at-risk” patients with atherosclerotic carotid artery disease, identifying vulnerable plaques. These applications may also help in the postoperative assessment of treatment options to manage cardiovascular risks.

     

Virtual intra-arterial angioscopy (VIA) of the carotid artery based on helical CT data

The purpose of this study was to visualize both the vessel wall and atherosclerotic plaques in virtual intra-arterial angioscopy (VIA) based on helical CT data sets. To achieve this in vitro, the optimal reconstruction threshold of the vessel wall was determined to be 56.4% of the maximum enhancement. Using this threshold, 20 patients suffering from symptomatic carotid disease were examined in a helical CT scanner. The degree of stenosis was defined using the North American Symptomatic Endarterectomy Trial (NASCET) criteria and compared with results from digital substraction angiography (DSA). Grading of stenoses was only possible by adding the separately computed plaque geometry to the geometry of the vessel wall in a second step. Correlation between VIA and DSA in low grade, medium grade and high grade stenosis was 88%, 93% and 71%, respectively. Complete occlusions were diagnosed correctly in all patients. Sensitivity and specificity for the correct diagnosis of high grade stenosis was 93.7% and 91.3%, respectively. A realistic depiction of intraluminal structures in carotid arteries can only be generated by displaying both the vessel wall and plaque structures simultaneously.     

CT angiographic analysis of carotid artery stenosis: comparison of manual assessment, semiautomatic vessel analysis, and digital subtraction angiography

BACKGROUND AND PURPOSE: To compare multisection CT angiography (CTA) analyzed with source/maximum intensity projection (MIP) images as well as semiautomated vessel analysis software with intra-arterial digital subtraction angiography (DSA) in detection and grading of carotid artery bifurcation stenosis. METHODS: Consecutive patients with sonography evidence of a marked internal carotid artery stenosis underwent both carotid CTA and DSA (37 patients, 73 vessels). In CTA, the grade of stenosis was determined using axial source and MIP images as well as vessel analysis. The scans were blind-analyzed by 2 neuroradiologists using the NASCET criteria. RESULTS: Correlation of CTA source/MIP images versus DSA estimates of stenosis (R = 0.95) was higher than for the vessel analysis method versus DSA (R = 0.89). Compared with DSA, CTA source/MIP images underestimated high (78.2% versus 86.4%, P < .05) and moderate grades of stenosis (57.3% versus 63.1%, P < .05) to a lesser extent than the vessel analysis method (68.5% versus 83.5% and 51.8% versus 63.1%, P < .05). For a high-grade stenosis, sensitivity and specificity of source/MIP image CTA were 75% and 96%, respectively, whereas for the vessel analysis method, they were 47% and 96%, respectively. For moderate stenosis, the source/MIP image CTA sensitivity and specificity were 88% and 82%, respectively, and for vessel analysis method, 62% and 82%, respectively. CTA detected all 4 occlusions. CONCLUSION: In evaluation of carotid stenosis, CTA provides an adequate, less invasive alternative with a high correlation to conventional DSA, though it tends to underestimate clinically relevant grades of stenosis. Its accuracy is not improved by semiautomated analysis. The data support the use of CTA in confirming carotid occlusion.     

Diagnostic accuracy of colour Doppler ultrasonography, CT angiography and blood-pool-enhanced MR angiography in assessing carotid stenosis: a comparative study with DSA in 170 patients

Purpose

This study was undertaken to prospectively evaluate the diagnostic performance of colour Doppler ultrasonography (CDUS), first-pass (FP) and steady-state (SS) contrast-enhanced magnetic resonance angiography (MRA) and computed tomography angiography (CTA) of the carotid arteries using digital subtraction angiography (DSA) as the reference standard.

Materials and methods

A total of 170 patients with previous cerebrovascular events and suspected carotid artery stenoses underwent CDUS, blood-pool MRA, CTA and DSA. Accuracy, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated for CDUS, FP MRA, SS MRA and CTA. The McNemar and Wilcoxon tests and receiver operating characteristic (ROC) curve analysis were used to determine significant differences (p<0.05) between the diagnostic performances of the four modalities, and the degree of stenosis was compared using linear regression.

Results

A total of 336 carotid bifurcations were studied. The area under the curve (AUC) for degree of stenosis was: CDUS 0.85±0.02, FP MRA 0.982±0.005, SS MRA 0.994±0.002 and CTA 0.997±0.001. AUC analysis showed no statistically significant difference between CTA and MRA (p=0.0174) and a statistically significant difference between CDUS and the other techniques (p<0.001). Plaque morphology analysis showed no significant difference between CTA and SS MRA; a significant difference was seen between CTA and SS MRA versus FP MRA (p=0.04) and CDUS (p=0.038). Plaque ulceration analysis showed a statistically significant difference between MRA and CTA (0.04< p<0.046) versus CDUS (p=0.019).

Conclusions

CTA is the most accurate technique for evaluating carotid stenoses, with a slightly better performance than MRA (97% vs. 95% for SS MRA and 92% for FP MRA) and a greater accuracy than CDUS (97% vs. 76%). Blood-pool contrast-enhanced SS sequences offer improved evaluation of degree of stenosis and plaque morphology with accuracy substantially identical to CTA.     

数字减影CT血管成像与彩色多普勒超声对颈动脉粥样硬化斑块检出率及斑块性质、狭窄程度判定的效果比较

目的比较数字减影CT血管成像（DSCTA）与彩色多普勒超声（CDUS）对颈动脉粥样硬化斑块的检出、斑块性质及狭窄程度判定的价值以及一致性。方法回顾性分析2015年1月至2017年10月就诊的可疑颈动脉狭窄患者90例,分别进行DSCTA与CDUS检查。采用卡方检验对比斑块分布、大小、斑块性质和狭窄程度。结果90例患者双侧颈部DSCTA检查发现52例颈动脉狭窄,3例为双侧狭窄,其中轻度狭窄29例、中度狭窄9例、重度狭窄12例,完全闭塞2例;检出斑块175处,其中钙化斑块133处、混合斑块30处、脂质斑块12处。90例患者双侧颈部CDUS检查发现54处颈动脉狭窄,3例为双侧狭窄,其中轻度狭窄26例、中度狭窄10例、重度狭窄16例,完全闭塞2例;检出斑块218处,其中钙化斑块138处、混合斑块39处、脂质斑块41处。DSCTA与CDUS诊断颈动脉狭窄的差异无统计学意义（χ2=0.75,P=0.861）;CDUS检查发现了更多的可见斑块及脂质斑块, < 5 mm的小斑块（60处）检出率明显高于DSCTA（25处）,差异有统计学意义（χ2=10.035,P=0.002）。结论DSCTA与CDUS对颈动脉狭窄的诊断效能均较高,具有较好的临床应用价值。CDUS对 < 5 mm斑块的检出优于DSCTA。     

Color-Doppler sonography vs CT-angiography in discriminating carotid atherosclerotic plaques for surgical treatment. A prospective study

PURPOSE: To compare the diagnostic accuracy of colour-Doppler sonography and CT-angiography in the selection of extracranial stenosis of the internal carotid artery to be treated with either endarterectomy or percutaneous transluminal angioplasty. MATERIALS AND METHODS: A total of 35 atherosclerotic plaques in 20 patients were studied with colour-Doppler sonography and CT-angiography (technical parameters: 2 mm raw thickness; 3.5 helical pitch; 2 mm image thickness; 1 mm reconstruction interval; non ionic contrast medium; Iodine concentration: 400 mg/ml, injection rate 5 ml/sec; Sure Start). On colour-Doppler sonography, we evaluated: the level of geometric stenosis (NASCET classification), maximum systolic peak velocity at the point of maximal stenosis and post-stenotic flow features. On CT-angiography we evaluated the level of geometric stenosis (NASCET classification) and the presence of calcium. We compared the degrees of geometric stenosis obtained with both techniques and considered the role each technique had in selecting candidates for surgery. CT-angiography was considered the gold standard. RESULTS: Three out of 35 plaques on CT-angiography were determining total carotid occlusion; all three of them were also shown on colour-Doppler sonography; 12 of 35 plaques were responsible for a degree of stenosis over 60% on CT-angiography and 11 of them (91.6%) were correctly shown on colour-Doppler sonography. 19 out of 35 plaques were determining a degree of stenosis less than 60% on CT-angiography and 11 of them (89.5%) were correctly shown on colour-Doppler sonography. The positive and negative predictive values were 92.3% and 95%, respectively, in detecting the plaques responsible for a degree of stenosis greater than 60%. DISCUSSION AND CONCLUSIONS: Colour-Doppler sonography is considered the first step in the diagnostic work-up of carotid atherosclerosis and evaluation of plaque conspicuity to select which plaques need to be treated with endarterectomy or percutaneous transluminal angioplasty. It has not been clearly demonstrated whether colour-Doppler sonography should be regarded as the sole preoperative imaging test or whether more expensive and invasive procedures such as CT-angiography, MRI and angiography are required. This study suggests that the accuracy of colour-Doppler sonography is comparable to that of CT-angiography in evaluating the degree of geometric stenosis caused by the plaque; in addition, it provides functional information on the plaque's haemodynamics effects. CT-angiography, rightly regarded as the gold standard, should be used for evaluating plaque composition (in particular predicting calcium presence and conspicuity) and in those cases in which the sonographic evaluation is not conclusive.     

Dual-energy CT head bone and hard plaque removal for quantification of calcified carotid stenosis: utility and comparison with digital subtraction angiography

We evaluated quantification of calcified carotid stenosis by dual-energy (DE) CTA and dual-energy head bone and hard plaque removal (DE hard plaque removal) and compared the results to those of digital subtraction angiography (DSA). Eighteen vessels (13 patients) with densely calcified carotid stenosis were examined by dual-source CT in the dual-energy mode (tube voltages 140 kV and 80 kV). Head bone and hard plaques were removed from the dual-energy images by using commercial software. Carotid stenosis was quantified according to NASCET criteria on MIP images and DSA images at the same plane. Correlation between DE CTA and DSA was determined by cross tabulation. Accuracies for stenosis detection and grading were calculated. Stenosis could be evaluated in all vessels by DE CTA after applying DE hard plaque removal. In contrast, conventional CTA failed to show stenosis in 13 out of 18 vessels due to overlapping hard plaque. Good correlation between DE plaque removal images and DSA images was observed (r ² = 0.9504) for stenosis grading. Sensitivity and specificity to detect hemodynamically relevant (>70%) stenosis was 100% and 92%, respectively. Dual-energy head bone and hard plaque removal is a promising tool for the evaluation of densely calcified carotid stenosis.     

A practical approach to CT angiography of the neck and brain

Computed tomography angiography (CTA) is a rapidly developing technology with great potential. This is particularly true for evaluating neurovascular disease. Clinical stroke because of atherosclerotic disease of the carotid and vertebral arteries is a common examination indication; areas of stenosis, and soft and calcified plaque along the entire vessel, not only at the carotid bifurcation, permit a full assessment of the patient's disease process. Other diseases including dissection, trauma, intracranial stenosis, thrombosis, and aneurysms can be readily diagnosed. Although duplex ultrasound may be a first line examination in many patients, both magnetic resonance angiography (MRA) and CTA offer distinct advantages over it. CTA and MRA are both highly accurate but CTA has several key advantages. CTA has been advanced by the development of improved multidetector CT (MDCT) and workstations that postprocess the data. Methods to obtain quality CTA images and to rapidly analyze the data for abnormalities are the subject of this chapter. In addition, evolving techniques in future CT scanners and workstations, and developing methods of vulnerable plaque and CT perfusion imaging are discussed.     

64层螺旋CT血管成像对颈动脉分叉处病变的临床应用

目的探讨64层螺旋CT血管成像(CTA)在诊断颈内动脉狭窄和粥样硬化斑块中的价值,并与当前血管成像的金标准DSA进行比较。方法对40例病人(80个颈动脉)进行了CTA和DSA检查,两项检查时间间隔不超过1周,并将CTA与DSA结果进行对照,计算出两者之间的敏感度和特异度。结果CTA对轻度(狭窄程度:0～29%)颈动脉狭窄和颈动脉闭塞显示得非常好,其敏感度和特异度均接近100%。在明确经DSA测量狭窄程度>50%的狭窄时,CTA敏感度、特异度分别为89%、91%。CTA在鉴别狭窄程度为50%～69%或70%～99%时的特异度高,而敏感度较低,分别为65%和73%。CTA同时可以检出DSA不能发现的所有类型的斑块。结论64层CTA在显示颈内动脉狭窄方面与DSA有很好的一致性,同时可发现与颈动脉狭窄相关的溃疡,而DSA只能显示狭窄。     

CT and ultrasound in the study of ulcerated carotid plaque compared with surgical results: potentialities and advantages of multidetector row CT angiography

BACKGROUND AND PURPOSE: Ulceration is a severe complication of carotid plaque. The purpose of this study was to evaluate the role and the diagnostic efficacy of multidetector row CT angiography (MDCTA) and ultrasound (US) echo color Doppler (US-ECD) in the study of patients with carotid plaque complicated by ulceration through the comparison with the surgical observation. MATERIALS AND METHODS: From January 2004 to October 2005, 237 patients, for a total of 474 carotid arteries, studied at first with color Doppler US, were analyzed using CT angiography. A total of 103 patients underwent a carotid endarterectomy. We analyzed stenosis degree, plaque composition, and presence of ulcerations. In a second phase, the data were compared with the surgical results when the MDCTA indicated surgical intervention. RESULTS: MDCTA found 31 ulcerations; the surgical confirmation underlined a 93.75% sensitivity and a 98.59% specificity. US-ECD performances were 37.5% and 91.5% for sensitivity and specificity, respectively. The number of patients who showed plaque ulcerations increased with the severity of stenosis. Furthermore, ulcerations of the carotid plaque occurred more often proximal than distal to the point of maximum stenosis, and this trend increased with the severity of the stenosis. We also determined that fatty plaques were more likely to be affected by ulcerations. CONCLUSIONS: The results of our study suggest that MDCTA detects with higher sensitivity and specificity the presence of ulcerated plaque compared with US-ECD, which has been demonstrated to be less effective in this evaluation. Considering the high MDCTA sensitivity and specificity for detection of plaque ulceration, we therefore recommend MDCTA as a useful step for correct presurgical planning.     

CT angiography in the assessment of carotid artery atherosclerosis

Objective: The aim of the study was to evaluate the ability of CT angiography (CTA) to detect atherosclerosis of the carotid arteries in comparison with 3D time-of-flight MR angiography (3D TOF MRA), using contrast angiography and intravascular ultrasound (IVUS) as a reference.Material and Methods: Contrast angiography and CTA were performed in 31 patients (mean age 65 years, range 45-79). The image quality was evaluated, atherosclerotic lesions were registered, and diameter stenosis degree was visually estimated from axial source images of CTA and 3D TOF MRA (21 patients), and results of interpretations were compared. The comparison of quantitative measurements was performed using IVUS as a reference.Results: Contrast angiography detected 51 lesions (mean diameter stenosis 50%, range 10-100%), and CTA detected all same lesions. CTA provided better image quality and consistency of image interpretation than 3D TOF MRA. IVUS verified 29 atherosclerotic lesions with a mean diameter stenosis of 35%, (range 4-40%). CTA yielded a sensitivity of 96% to 100% (≤10% or ≤20% diameter stenosis regarded as normal) for the detection of lesions with reference to IVUS.Conclusion: CTA seems feasible and accurate for the detection of atherosclerosis in carotid arteries.     

Assessment of carotid stenosis using three-dimensional T2-weighted dark blood imaging: Initial experience

Purpose:

To evaluate the use of a T2‐weighted SPACE sequence (T2w‐SPACE) to assess carotid stenosis via several methods and compare its performance with contrast‐enhanced magnetic resonance angiography (ceMRA).

Materials and Methods:

Fifteen patients with carotid atherosclerosis underwent dark blood (DB)‐MRI using a 3D turbo spin echo with variable flip angles sequence (T2w‐SPACE) and ceMRA. Images were coregistered and evaluated by two observers. Comparisons were made for luminal diameter, luminal area, degree of luminal stenosis (NASCET: North American Symptomatic Endarterectomy Trial; ECST: European Carotid Surgery Trial, and area stenosis), and vessel wall area. Degree of NASCET stenosis was clinically classified as mild (<50%), moderate (50%–69%), or severe (>69%).

Results:

Excellent agreement was seen between ceMRA and T2w‐SPACE and between observers for assessment of lumen diameter, lumen area, vessel wall area, and degree of NASCET stenosis (r > 0.80, P < 0.001). ECST stenosis was consistently higher than NASCET stenosis (48 ± 14% vs. 24 ± 22%, P < 0.001). Area stenosis (72 ± 2%) was significantly higher (P < 0.001) than both ESCT and NASCET stenosis.

Conclusion:

DB‐MRI of carotid arteries using T2w‐SPACE is clinically feasible. It provides accurate measurements of lumen size and degree of stenosis in comparison with ceMRA and offers a more reproducible measure of ECST stenosis than ceMRA. J. Magn. Reson. Imaging 2012;449‐455. © 2011 Wiley Periodicals, Inc.     

Magnetic resonance angiography with contrast media in the study of carotid arteries

PURPOSE: Purpose of our study was to determine the feasibility and accuracy of contrast enhanced Turbo-MRA (CE-MRA) in the evaluation of patients with carotid artery stenosis, using a dynamic technique with multiple acquisitions. MATERIAL AND METHODS: 37 patients with suspected carotid artery stenosis were studied with a 1.5 T magnet (Siemens Vision Plus) using, with a neck phased array coil, a dynamic tridimensional T1 weighted spoiled GRE (TR/TE/NEX: 3.8/1.4/1; Matrix = 110 x 160; FOV = 163 x 260 mm TA = 10 seconds for each sequence); 4 consecutive sequences were performed during the same breath hold, acquired after i.v. bolus injection with a power injector (Spectris, Medrad) of 15 ml of Gd-DTPA followed by 10 ml of saline solution (flow rate 2 ml/s). The beginning of the sequence coincided with the injection of Gd-DTPA. Images were reconstructed using a standard MIP algorithm, by selecting which of the sequences provided the highest enhancement. In all patients a DSA was also performed. Images were separately evaluated using conventional angiography as the gold standard and assessed for degree of stenosis by using NASCET criteria, and morphology of the plaque. RESULTS: CE-MRA correctly evaluated the degree of stenosis in 71 of the 74 patients, while overestimated the remaining 3 cases correctly evaluated by DSA. In 12 cases ulcerations were adequately demonstrated by one of the radiologist, while 11 on 12 were depicted by the other one. CE MRA allowed to detect tandem lesions of the internal carotid arteries (by both radiologists) in 13 of 74 carotids studied. Stenosis at the origin of the common carotid arteries were correctly detected in 9 cases. Sensitivity, specificity and accuracy were respectively of 98, 97 and 99%. DISCUSSION AND CONCLUSIONS: In order to perform an optimal CE-MRA a dynamic technique must be performed to avoid venous filling. The possibility to use ultrafast imaging allows to selectively image the carotid arteries without jugular filling. The well known tendency to overestimate the degree of stenosis has not been found in this group of patients. CE-MRA is a rapid, reliable method to evaluate patients with suspected carotid artery stenosis. These results allow to consider dynamic CE-MRA as a valid method for direct imaging of the carotid arteries.     

Carotid artery calcification on CT may independently predict stroke risk

OBJECTIVE: The purpose of our study was to quantitatively evaluate calcified atherosclerotic burden in the cervical carotid arteries using MDCT to determine the relationship of scores with luminal stenosis and symptomatology. MATERIALS AND METHODS: Calcium plaque volume was measured in 106 cervical carotid arteries (53 patients) using MDCT angiography. The study group included 32 asymptomatic patients (mean age, 70.2 +/- 8.7 [SD] years; 15 women, 17 men) and 21 patients with ischemic neurologic symptoms (69.6 +/- 12.9 years; eight women, 13 men). By vessel, there were 43 high-grade stenotic (> or = 60% by North American Symptomatic Carotid Endarterectomy Trial [NASCET] criteria), 15 moderate-grade stenotic (30-59%), and 44 mild-grade stenotic or normal (0-29%) vessels, with four excluded for prior carotid endarterectomy. Volume scores were calculated by summing the area of calcium in the common and extracranial internal carotid arteries on axial slices and multiplying by the slice increment. RESULTS: Controlling for cardiovascular risk factors and luminal stenosis, we found that scores were significantly related to the occurrence of symptoms (p = 0.003). Even with patient age as a covariant, patients with high-grade stenosis had significantly higher scores than those without high-grade disease (p = 0.004). Moreover, quantitative burden was associated with luminal stenosis on adjusted multivariate analysis (p = 0.034). The specificity and positive predictive value for high-grade luminal narrowing were notably lower on individual vessel analysis than on total score analysis, likely secondary to variability in vascular remodeling. CONCLUSION: Calcium scores in the cervical carotid arteries may represent an independent marker for luminal stenosis and ischemic symptoms. A prospective longitudinal study examining calcium levels and morbidity may be warranted to examine whether burden has a role in risk stratification.     

Three-dimensional rotational angiography of the carotid arteries with high-flow injection from the aortic arch. Preliminary experience

PURPOSE: Three-Dimensional Rotational Angiography (3DRA) is a new technique based on a rotational angiographic acquisition able to display arterial vessels in a 3D rendering mode. The system was mainly developed for neuroradiological evaluations but preliminary extracranial experiences have also been reported. The aim of our work was to compare the results of three-dimensional angiography of the carotid arteries done with high-flow injection of contrast medium from the aortic arch with the results of selective angiography. MATERIALS AND METHODS: Twenty patients underwent digital angiography of the supra-aortic vessels in order to quantify a stenosis of the carotid bifurcations previously detected at Doppler Ultrasound. Examinations were performed with the Philips Integris Allura system provided with the rotational angiography (RA) tool connected to a workstation for three-dimensional reconstruction able to display vessels in a 3D fashion (Volume Rendering, Gradient Rendering, Shaded Surface Display), automatically remove bone structures (cervical spine, calcified plaque, etc.) and perform an automatic analysis of the vessel diameter and surface area at the point of major stenosis and in the disease-free vessel segments above and below. The carotid evaluation was done either with selective catheterization and the two standard AP and LL projections and with RA after contrast medium injection from the aortic arch followed by 3D reconstruction. RESULTS: The comparison of the selective angiography and three-dimensional images was possible in 37 out of 40 carotid bifurcations (3 internal carotid arteries were occluded) and a good diagnostic quality was obtained in 35 out of 37 cases with an high correlation in the degree of stenosis. In 2/37 cases with calcified plaques the degree of stenosis was effectively demonstrated only after electronic subtraction of the calcified component of the plaque. CONCLUSIONS: The technique we propose proved to be feasible in all cases with a good correlation in the quantification of the degree of stenosis. The practical advantage of our technique is the almost complete exclusion of risks of neurological complications due to selective catheterization, and reduced examination time.     

MRI与DSA对颈动脉狭窄和粥样硬化斑块评估能力的比较

目的 探讨MRI与DSA对颈动脉粥样硬化患者血管狭窄及粥样硬化斑块病变特点评估能力的差异.方法 46例缺血性脑血管疾病患者,超声发现颈动脉粥样硬化斑块后分别行颈动脉MRI及DSA检查.颈动脉MR检查序列包括三维时间飞跃法(3D TOF)、T1WI、T2WI、质子密度加权成像( PDWI)及增强T1WI;颈动脉DSA检查分别摄取颈动脉的正位像和侧位像.观察颈动脉分叉处管腔的狭窄程度和斑块的病变特征,包括纤维帽的状况、斑块内出血和钙化.计算Kappa值分析MRI和DSA对血管狭窄程度判断结果的一致性;应用配对卡方检验检测两种方法对溃疡斑块的检出差异.结果 89支血管的MR图像质量均满足诊断要求.MRI显示血管狭窄程度的M(范围)为50％(16％～78％),DSA显示为47％(7％～73％),二者具有很好的一致性(Kappa值为0.882,P＜0.01).MRI发现34支血管具有斑块纤维帽破溃,DSA发现10支血管具有溃疡斑块(x2=20.346,P＜0.01).此外,MRI发现37支血管有斑块内出血,71支血管有斑块内钙化,而DSA均不能显示.结论 MRI可以准确判断颈动脉的狭窄程度,在显示溃疡斑块、斑块内出血以及钙化方面较DSA更具优势.     

CT Angiographic Features of Symptom-Producing Plaque in Moderate-Grade Carotid Artery Stenosis

BACKGROUND AND PURPOSE:Emerging evidence indicates that plaque imaging can improve stroke risk stratification in patients with carotid artery atherosclerosis. We studied the association between soft and hard (calcified) plaque thickness measurements on CTA and symptomatic disease status (ipsilateral stroke or TIA) in patients with moderate-grade carotid artery stenosis.MATERIALS AND METHODS:We measured soft-plaque and hard-plaque thickness on CTA axial source images in each carotid artery plaque in subjects with NASCET 50%–69% ICA stenosis. We used logistic regression and receiver operating characteristic analyses to assess the strength of the association between thickness measurements and prior stroke or TIA.RESULTS:Twenty of 72 vessels studied (27.7%) had ischemic symptoms ipsilateral to the side of moderate-grade carotid stenosis. Each 1-mm increase in soft plaque resulted in a 3.7 times greater odds of a prior ipsilateral ischemic event (95% CI, 1.9–7.2). Conversely, for each 1-mm increase in hard plaque, the odds of being symptomatic decreased by approximately 80% (OR, 0.22; 95% CI, 0.10%–0.48%). Receiver operating characteristic analysis showed an area under the curve of 0.88 by using soft-plaque thickness measurements to discriminate between asymptomatic and symptomatic plaques. Sensitivity and specificity were optimized by using a maximum soft-plaque thickness of 2.2 mm, which provided a sensitivity of 85% and a specificity of 83%.CONCLUSIONS:Simple CTA plaque-thickness measurements might differentiate symptomatic and asymptomatic moderate-grade carotid artery plaque. With further prospective validation, CTA plaque measures could function as an easily implementable tool for risk stratification in carotid artery disease.

Moderate-grade carotid artery stenosis is a risk factor for stroke, with pooled analysis from randomized controlled trials, including the European Carotid Surgery Trial, NASCET, and Veterans Affairs Symptomatic Trial, suggesting that unoperated patients with moderate-grade stenosis face up to a 20% 5-year risk of stroke.¹ Data pooled from these randomized controlled trials have also shown a modest stroke-risk-reduction benefit from carotid endarterectomy in patients with 50%–69% extracranial ICA stenosis.¹ However, the validity of these data has been questioned in the years since these trials were performed secondary to recent improvements in medical therapy, which have substantially reduced annual stroke rates in patients with carotid disease.^2,3 Consequently, there has been significant recent effort to develop new imaging markers that can identify patients with carotid artery disease at highest risk for stroke beyond luminal-diameter stenosis measurements.The 2 main pathophysiologic mechanisms underlying stroke risk in carotid artery disease are the propensity of plaque to locally embolize^4,5 and downstream hemodynamic compromise (low flow).^4,6,7 Although hypoperfusion and resultant slow flow from carotid disease likely play a role in a subset of strokes occurring in carotid stenosis, plaque instability causing distal embolus may be a relatively more influential etiologic factor for stroke in carotid disease in general.⁸ Although multisequence MR imaging characterization of plaque has allowed the in vivo discrimination of high-risk plaque tissue elements,^9–11 its use in clinical practice has been limited, given the time, expense, and challenge of performing multisequence carotid plaque MR imaging by using a dedicated carotid coil. CTA-based measurements of soft and hard (calcified) plaque determined on axial CTA source images have recently been proposed as potential simple alternative markers of vulnerable plaque in high-grade ICA stenosis.^12,13 Because plaque volumes are relatively smaller in moderate-grade stenosis, it is unclear to what extent such techniques are capable of identifying symptom-producing plaque in this group of patients in whom optimal treatment guidelines are controversial. Therefore, we used a cross-sectional study design to assess the association between plaque thickness measurements obtained from neck CTA and previous stroke or TIA in patients with moderate-grade ICA stenosis.     

Diagnostik von Karotisstenosen mit der mehrzeiligen CT-Angiographie

BACKGROUND: The accurate evaluation of carotid artery stenoses is important for therapeutic decision making. Catheter digital subtraction angiography (DSA) still represents the gold standard, while the advent of multislice CT (MSCT) has led to improved temporal and spatial resolutions of CTA. MATERIAL AND METHODS: In a pilot study, we investigated 14 diseased vessels in 9 symptomatic patients (7m, 2f; mean age 60.7+/-10,9 years) comparing biplanar DSA with standardized 16-slice MS-CTA. The degree of stenosis was evaluated in a consensus reading following modified NASCET criteria. RESULTS: DSA demonstrated 4 occlusions, 5 high-grade stenoses (>70%) and 5 lower-grade stenoses (<70%). One dissecting, infrapetrous stenosis was not adequately quantified by CTA due to a close topographic relation to the skull base. In the carotid bifurcation (n=13), an excellent correlation was demonstrated between DSA and CTA with a correlation coefficient of 0.99. CONCLUSION: MS-CTA has a good diagnostic potential in the evaluation of carotid artery stenoses. Larger studies will need to demonstrate the relative diagnostic value for different subtypes of stenosis and for different reader experience levels.     

Agreement between multi-detector-row CT angiography and US-ECD in quantification of carotid artery stenosis and plaque characterization

Purpose

The purpose of this work was to evaluate the agreement between ultra-sound echo-color Doppler (US-ECD) and multi-detector-row CT angiography (MDCTA) in the quantification of carotid artery stenosis as well as plaque characterization.

Materials and methods

From January 2012 to January 2013 forty-five patients who underwent both MDCTA and US-ECD for the study of carotid arteries, were evaluated (33 males, 12 females; age range 43–70 years; mean age of 59.6 years). For all subjects the following parameters were analyzed: stenosis degree by using the NASCET method, plaque morphology (regular versus irregular), type of the plaque (fatty, mixed and calcified) and presence of ulcerations. Statistical analysis was performed to calculate concordance between the two techniques employed.

Results

The agreement observed in the quantification of carotid artery stenosis was 94.4% with a kappa value of 0.9306 (95% confidence interval of 0.8612–1.0). In the definition of the type of plaque, the observed agreements were 91.1% and the kappa value was 0.8815 (95% confidence interval: 0.7920–0.9709). In the definition of plaque ulceration, the observed agreements were 88.4% but the kappa value was only 0.325 (95% confidence interval: 0.201–0.449). Agreement observed in the evaluation of plaque morphology was 78.3% with a kappa value of 0.513 (95% confidence interval: 0.452–0.574).

Conclusion

We observed a good agreement between US-ECD and MDCTA in the quantification of carotid artery stenosis and the assessment of plaque type. There was, however, a poor agreement in the evaluation of plaque ulceration. The use of US-ECD and MDCTA provides different results in the evaluation of plaque. Our results suggest that information derived from US-ECD should be always critically compared with other diagnostic techniques.