16层CT冠状动脉成像与选择性冠状动脉造影的对比研究

目的:探讨16层CT对冠状动脉粥样硬化病变的显示情况及临床价值。方法:39例患者进行16层CT冠状动脉造影检查(疑似冠心病者31例,PTCA术后8例)及选择性冠状动脉造影。分析16层CT对冠状动脉各节段的显示情况。以管腔直径减小>50%为标准,判定冠状动脉狭窄。分析16层CT诊断冠状动脉狭窄的敏感性、特异性及符合率,及对病变性质的显示情况。结果:16层CT对冠状动脉的总体显示率为94.8%(333/351)。评价冠状动脉病变的总体敏感性为82.2%,特异性为94.7%,符合率为86.0%。16层CT显示钙化及非钙化斑块混合存在致血管狭窄21处,高估3处;中间密度斑块致狭窄8处,高估3处;软斑块3处,无显著狭窄。16层CT能清晰显示支架位置、形态及远端血流,1例再狭窄,1例闭塞,余通畅,其结果与选择性冠状动脉造影一致。另外,16层CT显示冠状动脉起源变异2例,前降支冠状动脉瘤1例,室壁瘤1例,房间隔缺损1例。结论:16层CT冠状动脉成像是一种颇具潜力的无创性检查方法,能够较为准确、全面的评价冠状动脉病变。     

冠状动脉CT血管造影影像组学用于冠心病研究进展

冠状动脉CT血管造影(CCTA)是无创评估冠心病(CAD)及预测其风险分层的一线检查方法,对于识别冠状动脉斑块、评估血管周围脂肪组织、识别心肌缺血等具有重要临床价值。影像组学可提取高通量医学图像定量特征,具有广阔应用前景。本文对CCTA影像组学用于CAD研究进展进行综述。     

320排动态容积CT冠状动脉成像与冠状动脉造影对比观察

目的比较320排动态容积CT（DVCT）冠状动脉成像和冠状动脉造影（CAG）对诊断冠状动脉狭窄的准确性。方法对56例患者的672个冠状动脉节段进行320排DVCT冠状动脉成像及CAG,并进行对比分析。结果可用于评估的672个冠状动脉节段中,CAG显示病变140个,320排DVCT显示其中132个,320排DVCT诊断冠状动脉病变的总体敏感度、特异度、阳性预测值和阴性预测值分别为92.3%、99.2%、96.9%和97.9%。冠状动脉管壁严重钙化是图像质量失实的主要原因。结论 320排DVCT在显示冠状动脉病变时,具有较高的敏感度和特异度,并且对于病变程度的评估也比较准确,对于预测及早期诊断冠心病,有重要的临床应用价值。     

A review of adherence to the guidelines for coronary CT angiography quantitative stenosis grading thresholds in published research

Background: The degree of coronary stenosis of potential hemodynamic significance is central to the interpretation of coronary computed tomography angiography (CCTA), but has been variably defined in the literature. Societal guidelines have attempted to address this issue via recommended thresholds. Objectives: We surveyed the various thresholds for defining significant coronary stenosis reported in research published since the introduction of the Society for Cardiovascular Computed Tomography guidelines regarding the interpretation and reporting of CCTA. Methods: We systematically reviewed the results of bibliographic searches of all original research articles on CCTA, focusing on studies reporting > 25 subjects, to assess the definitions of severity of coronary lesions as found on CCTA. To enable comparisons, we stratified the methods of reporting lesion severity into ≥ 50%, 50% to 69%, and “others” (including infrequent reporting methods). Results: Fifty-nine11 published studies were identified and met inclusion criteria. Eighteen studies reported the severity of coronary stenosis using a definition of 50% to 69% as moderate stenosis; 35 studies defined ≥ 50% coronary stenosis as “stenosis,” “significant stenosis,” or “obstructive lesion” without distinguishing a threshold for moderate versus severe stenosis. Six studies utilized other thresholds, such as 20% to 75%, 40% to 69%, 40% to 70%, 40% to 79%, and 50% to 75% to define moderate coronary stenosis. Conclusions: Fifty-three of 59 studies were graded in accordance with the recommended threshold of ≥ 50% defining potentially significant stenosis, with 18 studies reporting precisely in accordance with the guidelines-recommended thresholds of ≥ 50% narrowing as defining moderate stenosis and ≥ 70% narrowing as defining severe stenosis. Six studies were reported using alternative thresholds for significant stenosis. However, a majority of research studies published since 2009 do not follow the societal guidelines for stenosis grading, since these studies do not clearly describe the degree of coronary stenosis.     

冠状动脉CT血管成像中人工智能诊断冠心病的准确性

目的 观察冠状动脉CT血管成像(CCTA)中人工智能(AI)诊断冠心病(CHD)的准确性.方法 回顾性分析105例临床拟诊CHD患者间隔2周内CCTA及有创冠状动脉造影(ICA)资料.以ICA结果为金标准,分别以患者、冠状动脉及其节段为单位,计算AI判断冠状动脉狭窄程度≥50％的敏感度、特异度、阳性预测值、阴性预测值和...     

Noninvasive coronary angiography using computed tomography

While noninvasive imaging of the coronary lumen remains challenging, great strides have been made with computed tomography. Two variations of computed tomography are used in the study of the coronary tree: multislice or multidetector computed tomography and electron-beam computed tomography. Both have high spatial and temporal resolutions as well as excellent signal-to-noise ratios, which allows major branches of the coronary tree to be depicted. Impaired image quality, due to dense calcifications and multiple image artifacts including coronary artery motion and breathing artifacts, limits the clinical utility of noninvasive coronary angiography. Early studies with electron-beam angiography demonstrated an overall sensitivity of 85% and specificity of 89% for the detection of obstructive coronary artery disease. With early diastolic imaging, the sensitivity and specificity increases to 92 and 93%, respectively (rather than 80% of the cardiac interbeat interval, where coronary motion is more pronounced). Multidetector computed tomography, with improved spatial resolution but decreased temporal resolution, produces results that vary depending on the equipment. Four-slice scanners have an average sensitivity of only 61%, and only 38% of patients have all four vessels or 15 segments available for analysis, due to both cardiac motion and calcification. Thinner slice collimation with eight and 16 slices have allowed for improved detection. Sensitivity and specificity improve to 80 and 86%, respectively. Furthermore, the number of assessable segments with eight-2011; to 16-2011;slice scanners improves significantly, compared with four-slice scanners (85 vs. 73%; p < 0.001). If only assessable segments are included in analysis, sensitivity and specificity for multidetector-row computed tomograpy improves to nearly 90%. Compared with magnetic resonance imaging, with a reported accuracy of 72% in the only multicenter study, computed tomography has great promise to become the primary method of noninvasive coronary angiography.     

双源CT冠状动脉造影图像质量与心率的关系

目的评估平均心率和心率范围对于双源CT冠状动脉造影图像质量的影响。方法收集行双源CT冠状动脉造影检查患者134例,所有CTA图像数据均包括完整的检查时的心电图数据。由两名熟悉心血管的CT医师在未知扫描期间心率和心率范围的情况下进行分析和分级。图像质量分为四级．并做统计学处理。结果评估了134个病人,共1751个冠状动脉节段。不同评分组冠状动脉节段数分别为：1分,899（51.34％）;2分,727（41．51％）;3分,114（6．51％）;4分,11（0．62％）。按照扫描期间的平均心率以70bpm为界分为≥70bpm组和〈70bpm组,5、12、14、16段两组图像质量未见差异．其余各段图像质量可见明显差异（t分别=3．38、3．13、2．28、2．90、2．95、3．50、4．16、3．89、3．24、2．89、3．49、3．51,P均〈0．05）。按照扫描期间心率范围（最高心率一最低心率）8bpm为界将所有患者分为≥8bpm组和〈8bpm组,在任何冠状动脉节段均未发现双源CT冠状动脉造影的整体图像质量与心率范围之间存在的相关性（t分别=0．45、1．41、0．97、1．27、1．00、1．05、1．69、0．84、0．99、1．48、0．44、0．46、0．48、0．43、0．44、0．20,P均〉0．05）。结论双源CT可以在很大范围的平均心率和心率变化范围内获得具有诊断意义的图像质量。     

斑块钙化负荷影响冠状动脉CT血管造影诊断管腔狭窄的准确性

目的  探究斑块钙化负荷对冠状动脉CT血管造影（CCTA）诊断管腔狭窄准确性的影响。方法  选取上海市嘉定区中心医院放射科于2019年2月~2022年1月收治的100例患者作为研究对象,所有患者均行冠状动脉造影与CCTA检查,钙化容积与钙化积分以血管段为单位进行记录,按照钙化容积与钙化积分不同将患者分为4组,分析各组血管管腔狭窄程度并探究CCTA判断斑块钙化不同容积与积分的管腔狭窄准确性。结果  100例患者中入选的钙化冠状动脉段共396个,按照15段进行计算,以管腔狭窄≥50%为有意义狭窄,得到敏感度、特异性、准确率、阳性预测值与阴性预测值分别为99.03%（204/206）、83.16%（158/ 190）、91.41%（362/396）、86.44%（204/236）、98.75%（158/160）;当钙化容积≤25 mm²、钙化积分≤80分时,敏感度、特异性、准确率、阳性预测值、阴性预测值均为100%;当196 mm²<钙化容积≤1375 mm²时,敏感度、特异性、准确率、阳性预测值、阴性预测值分别为85.71%、36.36%、75.47%、83.72%、40.00%;当钙化积分>200分时,敏感度、特异性、准确率、阳性预测值、阴性预测值分别为92.86%、75.00%、87.50%、89.66%、91.82%;CCTA诊断不同钙化容积管腔狭窄程度与不同钙化积分管腔狭窄程度的敏感度、特异性、准确率、阳性预测值、阴性预测值具有统计学意义（P<0.05）,其中诊断0~25 mm²钙化容积管腔狭窄程度与0~80分钙化积分管腔狭窄程度的敏感度、特异性、准确率、阳性预测值、阴性预测值最高。结论  不同斑块钙化负荷对CCTA诊断管腔狭窄程度准确性的影响存在差异,应引起临床重视。     

冠状动脉造影与多层螺旋CT冠脉成像在心肌桥诊断中的价值

目的：探讨多层螺旋CT冠脉成像（CCTA）与冠状动脉造影（CAG）在心肌桥（M B）诊断中的价值。方法：回顾性分析疑诊冠状动脉疾病的406例均进行CCTA和CAG检查者,两组采用双盲法CCTA和CAG分别独立阅片,由2名有经验的放射科医生与2名有经验的心内科介入医生采用单盲法阅片,经讨论后共同给出诊断。相互参照另一种检查结果后再次阅片,2次检出率,应用χ^2统计分析方法,判断2种方法发现M B有无差异。结果：双盲法CCTA发现M B 19例26段,CAG发现5例5段（P〈0.01）,差异有统计学意义。相互对照后再次评价,CCTA发现M B数量同前,CAG新发现3例,将新检出的3例患者行腺苷负荷核素心肌显像,相应节段心肌出现心肌低灌注,位置与CCTA一致,共检出8例,2种方法差异有统计学意义（P〈0.05）。结论：CCTA对M B和壁冠状动脉显示清晰,较CAG有更高的检出率,容易发现M B,有着特殊的临床诊断价值。     

64排螺旋CT冠状动脉成像与冠状动脉造影对心肌桥诊断价值的探讨

目的探讨64排螺旋CT血管造影（CTA）与冠状动脉造影（CAG）对心肌桥诊断的应用价值。方法 912例患者先后进行CTA检查和CAG检查,判断有无心肌桥-壁冠状动脉存在,将两者结果进行Kappa检验和配对t检验,判断两者间差异有无统计学意义。结果 CTA发现104例患者共121段存在心肌桥-壁冠状动脉,其中深在型心肌桥-壁冠状动脉42段,浅表型心肌桥-壁冠状动脉79段;而CAG发现97例患者共114段存在心肌桥-壁冠状动脉,其中深在型心肌桥-壁冠状动脉42段,浅表型心肌桥-壁冠状动脉72段。两者相比较,诊断深在型及浅表型心肌桥-壁冠状动脉两者Kappa一致性好（Kappa=1.000、0.877）,42段深在型-壁冠状动脉心肌桥长度CTA（11.25±4.20）mm vs CAG（9.56±3.67）mm,壁冠状动脉狭窄程度CTA（50±12）%vs CAG（59±12）%（均P〈0.01）;72段浅表型-冠状动脉心肌桥长度CTA（7.39±3.02）mm vs CAG（5.54±2.18）mm,壁冠状动脉狭窄程度CTA（31±10）%vs CAG（38±11）%（均P〈0.01）。结论 CTA能够诊断各型心肌桥-壁冠状动脉存在以及准确测量心肌桥长度,而测量壁冠状动脉狭窄程度则CAG优于CTA。     

Towards quantitative analysis of coronary CTA

The current high spatial and temporal resolution, multi-slice imaging capability, and ECG-gated reconstruction of multi-slice computed tomography (MSCT) allows the non-invasive 3D imaging of opacified coronary arteries. MSCT coronary angiography studies are currently carried out by the visual inspection of the degree of stenosis and it has been shown that the assessment with sensitivities and specificities of 90% and higher can be achieved. To increase the reproducibility of the analysis, we present a method that performs the quantitative analysis of coronary artery diseases with limited user interaction: only the positioning of one or two seed points is required. The method allows the segmentation of the entire left or right coronary tree by the positioning of a single seed point, and an extensive evaluation of a particular vessel segment by placing a proximal and distal seed point. The presented method consists of: (1) the segmentation of the coronary vessels, (2) the extraction of the vessel centerline, (3) the reformatting of the image volume, (4) a combination of longitudinal and transversal contour detection, and (5) the quantification of vessel morphological parameters. The method is illustrated in this paper by the segmentation of the left and right coronary trees and by the analysis of a coronary artery segment. The sensitivity of the positioning of the seed points is studied by varying the position of the proximal and distal seed points with a standard deviation of 6 and 8 mm (along the vessels course) respectively. It is shown that only close to the individual seed points the vessel centerlines deviate and that for more than 80% of the centerlines the paths coincide. Since the quantification depends on the determination of the centerline, no user variability is expected as long as the seed points are positioned reasonably far away from the vessel lesion. The major bottleneck of MSCT imaging of the coronary arteries is the potential lack of image quality due to limitations in the spatial and temporal resolution, irregular or high heart beat, respiratory effects, and variations of the distribution of the contrast agent: the number of rejected vessel segments in diagnostic studies is currently still too high for implementation in routine clinical practice. Also for the automated quantitative analysis of the coronary arteries high image quality is required. However, based upon the trend in technological development of MSCT scanners, there is no doubt that the quantitative analysis of MSCT coronary angiography will benefit from these technological advances in the near future.     

16层螺旋CT冠状动脉成像技术的探讨

目的:探讨16层螺旋CT冠状动脉血管成像技术。材料与方法:52例受检者行MSCT冠状动脉血管成像检查,使用美国GE公司16层螺旋CT,采用电影扫描序列,层厚为1.25mm,螺距为0.275∶1,对比剂(欧乃派克)2ml?蛐kg,注射速率3.5~4ml?蛐s,采用VR、MPR、CPR、VE进行图像后处理重建,显示冠状动脉主干及主要分支。结果:心率平稳,心率55~75次?蛐分,MSCT对冠状动脉主干及主要分支显示达到诊断要求;心率大于80次?蛐分时,冠状动脉的主要分支显示不清。结论:心率平稳且小于75次?蛐分,使用合适的对比剂及扫描参数,MSCT可满意显示冠状动脉主干及主要分支,可作为冠状动脉粥样硬化疾患的筛选,对血管搭桥和内支架放置术后复查的评价有较高临床价值。     

缩窄320排CT冠状动脉成像采集时间窗的可行性

目的 探讨缩窄320排CT冠状动脉CT血管成像（CCTA）采集时间窗的可行性。方法 收集90例接受CCTA的疑似冠心病患者。根据CCTA图像质量评分结果获得血管和患者层面最佳时相，依照不同心率患者CCTA最佳时相预估其由舒张期转移至收缩期的临界心率，预估采集时间窗缩窄范围。比较预估缩窄时间窗后（缩窄时间窗组）与CT设备预设时相（预设时相组）的图像质量，以及预估缩窄时间窗前后辐射剂量的差异。结果 患者层面CCTA最佳时相转移临界心率为70次/分。预估心率65~70次/分患者CCTA时间窗可缩窄为R-R间期72%~80%，心率70~95次/分患者可缩窄为R-R间期40%~50%。2组之间最佳血管时相和最佳患者时相图像质量差异均有统计学意义（P均<0.05）。预估缩窄时间窗前后有效辐射剂量差异有统计学意义（t=44.14，P<0.01），缩窄后辐射剂量降低约43%。结论 对屏气后心率稳定（心率波动≤5次/分）患者行CCTA时，根据不同心率缩窄采集时间窗，可提高图像质量、降低辐射剂量。     

Volume coronary angiography using targeted scans (VCATS): a new strategy in MR coronary angiography

The aim of this study was to explore the clinical possibilities of a new strategy for magnetic resonance imaging of the coronary arteries. Thirteen patients were studied by volume coronary angiography using targeted scans (VCATS) to visualize the major coronary arteries in a series of breath-holds. The proximal coronary arteries were clearly seen in 92% and the mid segments in 50–70% of the patients. VCATS was able to visualize a total vessel length of the left main (LM) (mean: 9.4 ± 3.4 mm), of the left anterior descending (LAD) 69 ± 20 mm, of the right coronary artery (RCA) 90 ± 33 mm and of the left circumflex (LCX) 41 ± 18 mm. There was a reasonable correlation between the VCATS and conventional coronary angiography (CAG) for vessel diameter (r = 0.71), with a slight overestimation of 0.7 mm by VCATS. There were nine significant stenoses present of which six were correctly detected, three were missed and one false positive was present. VCATS is fast strategy for visualizing the major coronary artery branches and has the potential to detect significant stenoses in these branches.     

Non-invasive coronary angiography with multi-detector computed tomography: comparison to conventional X-ray angiography

Selective coronary angiography introduced clinical coronary imaging in the late 1950s. The angiographic identification of high-grade coronary lesions in patients with acute and chronic symptomatic coronary artery disease (CAD) led to the development of surgical and percutaneous coronary revascularization. However, the fact that CAD remains the major cause of death in North America and Europe demonstrates the need for novel, complementary diagnostic strategies. These are driven by the need to characterize both increasingly advanced disease stages but also early, asymptomatic disease development. Complex revascularization techniques for patients with advanced disease stages will initiate a growing demand for 3-dimensional coronary imaging and integration of imaging modalities with new mechanical therapeutic devices. An emerging focus is atherosclerosis imaging with the goal to identify subclinical disease stages as the basis for pharmacological intervention aimed at disease stabilization or reversal. Non-invasive coronary imaging with coronary multidetector computed tomographic angiography (MDCTA) allows both assessment of luminal stenosis and subclinical disease of the arterial wall. Its complementary role in the assessment of early and advanced stages of CAD is increasingly recognized.     

多层螺旋CT冠状动脉成像的临床应用

目的 探讨多层螺旋CT在冠状动脉成像中的临床应用。方法 63例冠状动脉（其中冠状动脉内放置带膜支架4例，冠状动脉搭桥7例）行多层螺旋CT检查，回顾性重建心电门控轴位图像，并对冠状动脉主要分支血管进行多平面重建（MPR）、二维曲面重建（CPR）、最大密度投影法重建（MIP）、容积重建（VR）等后处理方法，对图像质量及冠状动脉疾病影像特点进行分析。结果 冠状动脉及主要分支显示优良率81．2％，能发现管壁钙化、狭窄等。质量差的图像主要表现有冠状动脉运动伪影、管腔显影不良等。结论 多层螺旋CT冠状动脉成像作为一种检查手段，能为临床冠状动脉疾病诊断和随访提供帮助。     

多层螺旋CT冠状动脉造影重建技术的比较

的:比较多层螺旋CT冠状动脉造影时各种重建技术评价冠状动脉疾病的准确性。材料和方法:20例患者做16层螺旋CT冠状动脉造影(回顾性心电门控、0.42s螺旋扫描),进行容积再现技术(VRT)、最大密度投影(MIP)、曲面重建(CPR)、仿真内窥镜(CTVE)等图像后处理,并与常规冠状动脉造影对照。结果:在20例患者的136节段(血管直径≥2mm)中,CT图像能满足诊断要求的有122节段(89.7%)。对于CT图像能满足诊断要求的冠状动脉节段,在横断位图像显示中度或中度以上狭窄的敏感度和特异度分别为81.2%和94.4%,CTVE为71.8%和84.4%,MIP为68.7%和84.4%,CPR为65.6%和87.7%,VRT为65.6%和74.4%。将5种重建技术结合后显示中度或中度以上狭窄的敏感度和特异度分别为87.5%和96.6%。结论:横断面图像显示中度或中度以上狭窄的敏感度和特异度最高。在冠状动脉中高度狭窄的诊断上,16层螺旋CT冠状动脉造影是一种有效的无创性诊断方法。     

对比单次屏气与两次屏气法减影冠状动脉CT血管造影评估严重钙化冠状动脉狭窄

目的 对比分析单次屏气与两次屏气方法获得减影冠状动脉CT血管造影(sub-CCTA)对评估严重钙化(Agatston钙化积分＞400)冠状动脉狭窄的价值。方法 回顾性分析60例疑诊冠心病患者CCTA及侵入性冠状动脉造影(ICA)资料,根据扫描方法分为单次屏气组(n=32)及两次屏气组(n=28)。针对CCTA显示严重钙化节段,对比2组常规CCTA(con-CCTA)和sub-CCTA图像质量评分;以ICA结果为标准,绘制受试者工作特征(ROC)曲线,计算曲线下面积(AUC),评估CCTA诊断目标节段狭窄率≥50%的效能。结果 单次屏气组中,CCTA共检出134个冠状动脉节段存在严重钙化,其中78个节段ICA显示狭窄率≥50%;con-CCTA图像质量评分为3.0(2.0,3.0),低于sub-CCTA 。两次屏气组中,CCTA共检出127个冠状动脉节段存在严重钙化,其中74个节段ICA显示狭窄率≥50%;con-CCTA图像质量评分为3.0(2.0,3.0),低于sub-CCTA 。con-CCTA评估单次、两次屏气组目标节段狭窄率≥50%的AUC(0.780、0.767)均低于sub-CCTA(AUC=0.903、0.898,Z=4.198、3.470,P均＜0.010)。单次屏气sub-CCTA图像质量评分高于两次屏气sub-CCTA(Z=－2.954,P=0.030),而诊断目标节段狭窄率≥50%的准确率差异无统计学意义(Z=0.129,P=0.900)。结论 单次与两次屏气法sub-CCTA评估严重钙化冠状动脉节段狭窄程度效能相仿,但前者图像质量更佳。     

Registration of 3D CT angiography and cardiac MR images in coronary artery disease patients

A method for the registration of 3D cardiac CT angiography (CTA) and magnetic resonance (MR) data sets based on their myocardial epicardial surfaces is introduced. The approach relies on temporally registered data sets obtained based on the electrocardiogram recorded during the CTA acquisition and the timing characteristics of the MR acquisition. The myocardial epicardial surfaces were identified in the reformatted CTA and MR data sets using a 3D semi-automated segmentation algorithm. This algorithm was implemented, evaluated on clinical data, and compared to a set of manual outlines during the course of this study. The registration of the CTA and MR data sets was based on the iterative closest point algorithm, which minimizes the distance between the surfaces defined by the epicardial outlines in each data set. The proposed technique was applied to data obtained from 11 patients with coronary artery disease. The CTA data was reformatted based on the registration results and the location of the MR imaging planes. The resulting CTA-MR image pairs were evaluated qualitatively by two experts, who graded the majority of the cases as either excellent or acceptable (11 of 11 cases for one reader, and 9 of 11 for the other). The results were evaluated quantitatively based on the distance between the registered epicardial surfaces. The quantitative measures indicated that the registered surfaces were within two pixels of one another (on average). The registration results were used to generate combined 3D renderings of information extracted from both data sets for visualization purposes.     

仿真内镜用于双源CT冠状动脉成像的初步经验

目的 初步探讨双源CT冠状动脉成像时利用仿真内镜诊断冠状动脉疾病的潜在价值.方法 使用Fly-through软件对40例双源CT冠状动脉成像病例行仿真内镜观察,并与CT冠状动脉成像常规方法和传统冠状动脉造影术进行比较.结果 40例患者共120支冠状动脉中,92％(110/120)的冠状动脉可行仿真内镜成像;仿真内镜判断有意义的冠状动脉狭窄正确率为85％( 41/48);常规CT冠状动脉成像不能判断的9处严重钙化,仿真内镜显示为显著或高度狭窄;4枚冠状动脉支架内和3支桥血管仿真内镜显示通畅.结论 仿真内镜可立体显示正常和病变冠状动脉腔内情况,是CT冠状动脉成像后处理方法的的重要补充.