Coronary artery centerline extraction in cardiac CT angiography using a CNN-based orientation classifier

Coronary artery centerline extraction in cardiac CT angiography (CCTA) images is a prerequisite for evaluation of stenoses and atherosclerotic plaque. In this work, we propose an algorithm that extracts coronary artery centerlines in CCTA using a convolutional neural network (CNN).In the proposed method, a 3D dilated CNN is trained to predict the most likely direction and radius of an artery at any given point in a CCTA image based on a local image patch. Starting from a single seed point placed manually or automatically anywhere in a coronary artery, a tracker follows the vessel centerline in two directions using the predictions of the CNN. Tracking is terminated when no direction can be identified with high certainty. The CNN is trained using manually annotated centerlines in training images. No image preprocessing is required, so that the process is guided solely by the local image values around the tracker’s location.The CNN was trained using a training set consisting of 8 CCTA images with a total of 32 manually annotated centerlines provided in the MICCAI 2008 Coronary Artery Tracking Challenge (CAT08). Evaluation was performed within the CAT08 challenge using a test set consisting of 24 CCTA test images in which 96 centerlines were extracted. The extracted centerlines had an average overlap of 93.7% with manually annotated reference centerlines. Extracted centerline points were highly accurate, with an average distance of 0.21 mm to reference centerline points. Based on these results the method ranks third among 25 publicly evaluated methods in CAT08. In a second test set consisting of 50 CCTA scans acquired at our institution (UMCU), an expert placed 5448 markers in the coronary arteries, along with radius measurements. Each marker was used as a seed point to extract a single centerline, which was compared to the other markers placed by the expert. This showed strong correspondence between extracted centerlines and manually placed markers. In a third test set containing 36 CCTA scans from the MICCAI 2014 Challenge on Automatic Coronary Calcium Scoring (orCaScore), fully automatic seeding and centerline extraction was evaluated using a segment-wise analysis. This showed that the algorithm is able to fully-automatically extract on average 92% of clinically relevant coronary artery segments. Finally, the limits of agreement between reference and automatic artery radius measurements were found to be below the size of one voxel in both the CAT08 dataset and the UMCU dataset. Extraction of a centerline based on a single seed point required on average 0.4 ± 0.1 s and fully automatic coronary tree extraction required around 20 s.The proposed method is able to accurately and efficiently determine the direction and radius of coronary arteries based on information derived directly from the image data. The method can be trained with limited training data, and once trained allows fast automatic or interactive extraction of coronary artery trees from CCTA images.     

Semiautomatic carotid lumen segmentation for quantification of lumen geometry in multispectral MRI

Quantitative information about the geometry of the carotid artery bifurcation is relevant for investigating the onset and progression of atherosclerotic disease. This paper proposes an automatic approach for quantifying the carotid bifurcation angle, carotid area ratio, carotid bulb size and the vessel tortuosity from multispectral MRI. First, the internal and external carotid centerlines are determined by finding a minimum cost path between user-defined seed points where the local costs are based on medialness and intensity. The minimum cost path algorithm is iteratively applied after curved multi-planar reformatting to refine the centerline. Second, the carotid lumen is segmented using a topology preserving geodesic active contour which is initialized by the extracted centerlines and steered by the MR intensities. Third, the bifurcation angle and vessel tortuosity are automatically extracted from the segmented lumen. The methods for centerline tracking and lumen segmentation are evaluated by comparing their accuracy to the inter- and intra-observer variability on 48 datasets (96 carotid arteries) acquired as part of a longitudinal population study. The evaluation reveals that 94 of 96 carotid arteries are segmented successfully. The distance between the tracked centerlines and the reference standard (0.33mm) is similar to the inter-observer variation (0.32mm). The lumen segmentation accuracy (average DSC=0.89, average mean absolute surface distance=0.31mm) is close to the inter-observer variation (average dice=0.92, average mean surface distance=0.23mm). The correlation coefficient of manually and automaticly derived bifurcation angle, carotid proximal area ratio, carotid proximal bulb size and vessel totuosity quantifications are close to the correlation of these measures between observers. This demonstrates that the automated method can be used for replacing manual centerline annotation and manual contour drawing for lumen segmentation in MRIs data prior to quantifying the carotid bifurcation geometry.     

Multiple hypothesis template tracking of small 3D vessel structures

A multiple hypothesis tracking approach to the segmentation of small 3D vessel structures is presented. By simultaneously tracking multiple hypothetical vessel trajectories, low contrast passages can be traversed, leading to an improved tracking performance in areas of low contrast. This work also contributes a novel mathematical vessel template model, with which an accurate vessel centerline extraction is obtained. The tracking is fast enough for interactive segmentation and can be combined with other segmentation techniques to form robust hybrid methods. This is demonstrated by segmenting both the liver arteries in CT angiography data, which is known to pose great challenges, and the coronary arteries in 32 CT cardiac angiography data sets in the Rotterdam Coronary Artery Algorithm Evaluation Framework, for which ground-truth centerlines are available.     

Visual assessment of coronary artery stenosis with electrocardiographically-gated multislice computed tomography

BACKGROUND: With faster image acquisition times and thinner slice widths, multislice detector computed tomography (MSCT) allows visualization of human coronary arteries. Significantly improved image quality, with high resolution and new software for three-dimensional post-processing, has made noninvasive examination of the cavities within human body possible. OBJECTIVE: The aims of this study are to evaluate the diagnostic accuracy of ECG-gated MSCT for the detection of significant coronary artery stenosis and occlusions. METHODS: In 25 patients (19 male and 6 female aged 65+/-9 years) with suspected obstructive coronary artery disease, ECG-gated MSCT angiography was performed with an 8-slice MSCT scanner. Visual coronary arteries were simulated in three coronary arteries. Conventional coronary angiographies were performed in all patients. And coronary lesions in MSCT were estimated by two observers, who did not know the results of the coronary angiography. RESULTS: Current MSCT allows visual coronary artery with good image quality. The overall sensitivity for diagnosing significant coronary stenosis were 75.0%, the specificity was 95.6%. The positive and negative predictive values were 84.9 and 92.2%, respectively. The accuracy of MSCT for detecting coronary stenosis is the highest in the left main tranck and left anterior descending coronary artery, and lowest in the circumflex coronary artery. CONCLUSION: MSCT was feasible for the detection of coronary artery stenosis.     

Vascular Centerline Extraction in 3D MR Angiograms for Phase Contrast MRI Blood Flow Measurement

The accuracy of 2D phase contrast (PC) magnetic resonance angiography (MRA) depends on the alignment between the vessels and the imaging plane. PC MRA imaging of blood flow is challenging when the flow in several vessels is to be evaluated with one acquisition. For this purpose, semi-automatic determination of the plane most perpendicular to several vessels is proposed based on centerlines extracted from 3D MRA. Arterial centerlines are extracted from 3D MRA based on iterative estimation-prediction, multi-scale analysis of image moments, and a second-order shape model. The optimal plane is determined by minimizing misalignment between its normal vector and the centerlines’ tangent vectors. The method was evaluated on a phantom and on 35 patients, by seeking the optimal plane for cerebral blood flow quantification simultaneously in internal carotids and vertebral arteries. In the phantom, difference of orientation and of height between known and calculated planes was 1.2° and 2.5 mm, respectively. In the patients, all but one centerline were correctly extracted and the misalignment of the plane was within 12° per artery. Semi-automatic centerline extraction simplifies and automates determination of the plane orthogonal to one vessel, thereby permitting automatic simultaneous minimization of the misalignment with several vessels in PC MRA.     

Evaluation of coronary arterial stenoses before and after percutaneous transluminal coronary angioplasty using magnetic resonance coronary angiography

Summary

X ray coronary angiography has become an indispensable technique for assessing coronary heart disease. However, repeated angiography causes various complications in some patients. We evaluated coronary stenoses non-invasively, before and after percutaneous transluminal coronary angioplasty (PTCA), using magnetic resonance coronary angiography (MRCA). Twenty-four patients underwent MRCA and PTCA. MRCA was performed using a gradient echo sequence with K-space segmentation. MRCA images were classified as normal, vessel narrowing, reduced intensity, breakage of vessel and inability to image. MRCA performed before PTCA showed abnormal findings in all patients (reduced intensity in five, vessel narrowing in four, breakage of vessel in 13, inability to image in two). Although every patient underwent successful PTCA, MRCA performed after PTCA showed abnormal findings (reduced intensity in seven, vessel narrowing in five) in half the patients. Patients who had complex lesions had a tendency to exhibit abnormal findings in MRCA. MRCA provided useful information parallel to X ray angiography before PTCA. However, after successful PTCA, it still showed abnormal findings in half the patients. It was considered that MRCA over-estimates medium stenoses-and has difficulty imaging complex lesions or tortuous vessels. It was concluded that MRCA has potential as a non-invasive examination technique to image coronary arteries before and after PTCA.     

Automated Registration of Freehand B-Mode Ultrasound and Magnetic Resonance Imaging of the Carotid Arteries Based on Geometric Features

An automated method for registering B-mode ultrasound (US) and magnetic resonance imaging (MRI) of the carotid arteries is proposed. The registration uses geometric features, namely, lumen centerlines and lumen segmentations, which are extracted fully automatically from the images after manual annotation of three seed points in US and MRI. The registration procedure starts with alignment of the lumen centerlines using a point-based registration algorithm. The resulting rigid transformation is used to initialize a rigid and subsequent non-rigid registration procedure that jointly aligns centerlines and segmentations by minimizing a weighted sum of the Euclidean distance between centerlines and the dissimilarity between segmentations. The method was evaluated in 28 carotid arteries from eight patients and six healthy volunteers. First, the automated US lumen segmentation method was validated and optimized in a cross-validation experiment. Next, the effect of the weighting parameter of the proposed registration dissimilarity metric and the control point spacing in the non-rigid registration was evaluated. Finally, the proposed registration method was evaluated in comparison to an existing intensity-and-point-based method, a registration using only the centerlines and a registration using manual US lumen segmentations. Registration accuracy was measured in terms of the mean surface distance between manual US segmentations and the registered MRI segmentations. The average mean surface distance was 0.78 ± 0.34 mm for all subjects, 0.65 ± 0.09 mm for healthy volunteers and 0.87 ± 0.42 mm for patients. The results for the complete set were significantly better (Wilcoxon test, p < 0.01) than the results for the intensity-and-point-based method and the centerline-based registration method. We conclude that the proposed method can robustly and accurately register US and MR images of the carotid artery, allowing multimodal analysis of the carotid plaque to improve plaque assessment.     

Vessel centerline reconstruction from non-isocentric and non-orthogonal paired monoplane angiographic images

Purpose

Three-dimensional reconstruction of a vessel centerline from paired planar coronary angiographic images is critical to reconstruct the complex three-dimensional structure of the coronary artery lumen and the relative positioning of implanted devices. In this study, a new vessel centerline reconstruction method that can utilize non-isocentric and non-orthogonal pairs of angiographic images was developed and tested.

Methods

Our new method was developed in in vitro phantom models of bifurcated coronary artery with and without stent, and then tested in in vivo swine models (twelve coronary arteries). This method was also validated using data from six patients.

Results

Our new method demonstrated high accuracy (root mean square error?=?0.27 mm or 0.76 pixel), and high reproducibility across a broad imaging angle (20°–130°) and between different cardiac cycles in vitro and in vivo. Use of this method demonstrated that the vessel centerline in the stented segment did not deform significantly over a cardiac cycle in vivo. In addition, the total movement of the isocenter in each image could be accurately estimated in vitro and in vivo. The performance of this new method for patient data was similar to that for in vitro phantom models and in vivo animal models.

Conclusions

We developed a vessel centerline reconstruction method for non-isocentric and non-orthogonal angiographic images. It demonstrated high accuracy and good reproducibility in vitro, in vivo, and in clinical setting, suggesting that our new method is clinically applicable despite the small sample size of clinical data.

     

Novel clinical applications of state-of-the-art multi-slice computed tomography

Recent years have witnessed a rapid development of multi-slice computed tomography (MSCT) technology. The number of detector rows has increased from 4-slices to the current availability of 64-slice and even 320-slice systems. In addition, images are acquired with thinner slices and faster rotation times resulting in substantially improved image quality and diagnostic accuracy. Simultaneously, effective dose reduction acquisition techniques have been developed allowing considerable reduction of the radiation dose. Conceivably, these advancements may allow further expansion of the use of MSCT beyond the visual assessment of the presence or absence of significant coronary artery disease. Indeed, a particular advantage of the technique is that in addition to evaluation of the coronary arteries it also allows assessment of cardiac structures and function. The purpose of the current review is to discuss several novel applications of cardiac MSCT, including stenosis quantification, atherosclerotic plaque imaging and prognostification as well as imaging of left ventricular function, aortic and mitral valve anatomy using state-of-the-art technology.     

A quantitative evaluation of the three dimensional reconstruction of patients' coronary arteries

Background: Through extensive training and experience angiographers learn to mentally reconstruct the three dimensional (3D) relationships of the coronary arterial branches. Graphic computer technology can assist angiographers to more quickly visualize the coronary 3D structure from limited initial views and then help to determine additional helpful views by predicting subsequent angiograms before they are obtained. Methods: A new computer method for facilitating 3D reconstruction and visualization of human coronary arteries was evaluated by reconstructing biplane left coronary angiograms from 30 patients. The accuracy of the reconstruction was assessed in two ways: 1) by comparing the vessel's centerlines of the actual angiograms with the centerlines of a 2D projection of the 3D model projected into the exact angle of the actual angiogram; and 2) by comparing two 3D models generated by different simultaneous pairs on angiograms. The inter- and intraobserver variability of reconstruction were evaluated by mathematically comparing the 3D model centerlines of repeated reconstructions. Results: The average absolute corrected displacement of 14,662 vessel centerline points in 2D from 30 patients was 1.64 ± 2.26 mm. The average corrected absolute displacement of 3D models generated from different biplane pairs was 7.08 ± 3.21 mm. The intraobserver variability of absolute 3D corrected displacement was 5.22 ± 3.39 mm. The interobserver variability was 6.6 ± 3.1 mm. Conclusions: The centerline analyses show that the reconstruction algorithm is mathematically accurate and reproducible. The figures presented in this report put these measurement errors into clinical perspective showing that they yield an accurate representation of the clinically relevant information seen on the actual angiograms. These data show that this technique can be clinically useful by accurately displaying in three dimensions the complex relationships of the branches of the coronary arterial tree.     

Coronary arterial malformation depicted at multi-slice CT angiography

We present a case of a 57-year-old woman with an unremarkable medical history except for a continuous cardiac murmur at the left second and third interspaces. Transthoracic echocardiography revealed an unusual chamber in front of the heart. To evaluate the precise anatomy of this abnormality, multi-slice computed tomographic (MSCT) imaging was performed. MSCT angiography with retrospective ECG gating showed a coronary arterial malformation with fistulous communications to the coronary artery, pulmonary artery and the root of aorta. Images from MSCT coronary angiography can be helpful in understanding the tortuous configuration of the coronary arterial malformation.     

Non-invasive coronary angiography: the clinical value of multi-slice computed tomography in the assessment of patients with prior coronary bypass surgery

Background Contrast enhanced multi-slice computed tomography (MSCT) is the leading modality in non-invasive coronary angiography (CTA) today. We investigated MSCT based assessment of coronary artery bypass grafts (CABG) by analyzing assets and drawbacks of CTA in order to define demands on latest technology. Methods In a clinical setting 39 CABG patients (69.2 ± 1.4 years; male n = 36) underwent CTA (collimation 16 × 0.75 mm, contrast medium 100 ml; 320 mAs, 120 KV). Ninety-seven CABG (61 venous, 36 arterial grafts) were evaluated. A subgroup of 18 patients underwent additional invasive coronary angiography (CA). Results CTA for CABG assessment resulted in an overall sensitivity (sens.) of 100%, specificity (spec.) of 92.4% and positive and negative predictive values (PPV, NPV) of 60% and 100%, respectively. CABG anastomoses showed slightly inferior diagnostic accuracy than other CABG segments. Limitations in imaging quality caused 21% unevaluable segments of the CABG anastomoses. Evaluation of native vessel segments proximal and distal to the anastomoses resulted in a sens, spec, PPV and NPV of 57.5, 94.6, 92 and 67.3%, respectively. With 28.5% unevaluable segments, the native vessel segments showed serious limitations in imaging quality. Radiation exposure was 9.88 ± 3.20 mSv (9.69 ± 3.25 mSv male; 12.08 ± 1.35 mSv female). Conclusion 16-slice MSCT based CABG assessment offers sufficient diagnostic accuracy. However, focussing on the bypass anastomoses and the native revascularized coronary arteries, clinical value is limited.     

Coronary vessel visualization using true 16-row multi-slice computed tomography technology

Background :Multi-slice computed tomography (MSCT) scanners with retrospective ECG-gating permit visualization of the coronary arteries. Limited spatial and temporal resolution as well as breathing artefacts due to the scan time can cause poor distal vessel segment and side branch visualization. The latest MSCT generation with true 16-detector slices (Sensation 16 ^®, Siemens, Forchheim, Germany) provides furthermore improved temporal and spatial resolution, as well as significantly reduced scan time. To assess, whether this technical improvement has also an impact on image quality we conducted the following study. Methods and material :Sixty-two consecutive patients (33 male, 29 female, mean age 63±8 [47–79] years, heart rate after -blockade 63±7 [45–86] bpm) with suspicion of coronary artery disease (CAD) were examined by cardiac MSCT. Parameter settings were: 0.75mm collimation, 2.8mm table feed/rotation, caudocranial scan direction, 80cc contrast media biphasic injection protocol, gantry rotation time 375ms, temporal resolution 188ms). Thirteen coronary segments (sgts) were evaluated in each patient (total number: 806sgts). Image quality of each segment was determined as: excellent – free of motion artefacts, good – mild motion artefacts, relevant artefacts – still diagnostic value, severe calcification and insufficient image quality – not visualized segment. Results :301/806 (37%) sgts showed excellent and 294/806 (36%) sgts good image quality. Relevant artefacts were seen in 107/806 (13%) sgts, calcifications in 41/806 (5%) sgts. 63/806 (8%) sgts could not be visualized (34 of them (54%) either segment 9 or 10). Diagnostic image quality was achieved in 702/806 (87%) sgts. Conclusions :Due to true 16-slice technology and faster gantry rotation time MSCT image quality could be improved and allows a visualization of the entire coronary tree. Larger, randomized, catheter-controlled studies have to be conducted to determine, whether this improved visualization also translates into better diagnostic accuracy.Both authors contributed equally     

Automated neurite extraction using dynamic programming for high-throughput screening of neuron-based assays

High-throughput screening (HTS) of cell-based assays has recently emerged as an important tool of drug discovery. The analysis and modeling of HTS microscopy neuron images, however, is particularly challenging. In this paper we present a novel algorithm for extraction and quantification of neurite segments from HTS neuron images. The algorithm is designed to be able to detect and link neurites even with complex neuronal structures and of poor imaging quality. Our proposed algorithm automatically detects initial seed points on a set of grid lines and estimates the ending points of the neurite by iteratively tracing the centerline points along the line path representing the neurite segment. The live-wire method is then applied to link the seed points and the corresponding ending points using dynamic programming techniques, thus enabling the extraction of the centerlines of the neurite segments accurately and robustly against noise, discontinuity, and other image artifacts. A fast implementation of our algorithm using dynamic programming is also provided in the paper. Any thin neurite and its segments with low intensity contrast can be well preserved by detecting the starting and ending points of the neurite. All these properties make the proposed algorithm attractive for high-throughput screening of neuron-based assays.     

多层螺旋CT冠状动脉造影的成像技术及临床应用价值

目的:分析多层螺旋CT冠状动脉造影的成像技术及价值。方法:将2018年1月-2019年1月期间我院收治的100例疑似冠心病患者作为研究对象,患者均给予冠状动脉造影检查和多层螺旋CT(MSCT)检查,对比两种检查方式的效果。结果:(1)对比两种诊断方式准确率:冠状动脉造影检查结果显示100例患者均为冠心病,诊断准确率为100%,MSCT结果显示98例患者为冠心病,诊断准确率为98%,组间数据无统计学意义(P>0.05);(2)多层螺旋CT显示情况分析:对于冠状动脉1~3级分支MSCT均能够清晰显示,但在4级冠状动脉分支显示效果较差。结论:MSCT能够清晰显示冠状动脉1~3级和4级部分分支,对冠心病患者具有较高的诊断准确率,使用价值高,值得推广。     

Automatic centerline extraction of coronary arteries in coronary computed tomographic angiography

Coronary computed tomographic angiography (CCTA) is a non-invasive imaging modality for the visualization of the heart and coronary arteries. To fully exploit the potential of the CCTA datasets and apply it in clinical practice, an automated coronary artery extraction approach is needed. The purpose of this paper is to present and validate a fully automatic centerline extraction algorithm for coronary arteries in CCTA images. The algorithm is based on an improved version of Frangi's vesselness filter which removes unwanted step-edge responses at the boundaries of the cardiac chambers. Building upon this new vesselness filter, the coronary artery extraction pipeline extracts the centerlines of main branches as well as side-branches automatically. This algorithm was first evaluated with a standardized evaluation framework named Rotterdam Coronary Artery Algorithm Evaluation Framework used in the MICCAI Coronary Artery Tracking challenge 2008 (CAT08). It includes 128 reference centerlines which were manually delineated. The average overlap and accuracy measures of our method were 93.7% and 0.30 mm, respectively, which ranked at the 1st and 3rd place compared to five other automatic methods presented in the CAT08. Secondly, in 50 clinical datasets, a total of 100 reference centerlines were generated from lumen contours in the transversal planes which were manually corrected by an expert from the cardiology department. In this evaluation, the average overlap and accuracy were 96.1% and 0.33 mm, respectively. The entire processing time for one dataset is less than 2 min on a standard desktop computer. In conclusion, our newly developed automatic approach can extract coronary arteries in CCTA images with excellent performances in extraction ability and accuracy.     

ECG-gated multislice spiral computed tomography to clarify lesion severity in a case of left main stenosis

This case report describes the use of retrospectively ECG-gated multislice spiral computed tomography (MSCT) for evaluation of lesion severity in a patient with relevant left main stenosis by visual analysis of the coronary angiogram. For further diagnostic evaluation the patient underwent intravascular ultrasound (IVUS) imaging, which showed a maximal 30% area stenosis, and MSCT, which demonstrated a maximal 48% area stenosis. MSCT was useful in this case to defer cardiac surgery and might be used as a noninvasive alternative to IVUS imaging in case of doubtful lesion severity.     

Utility of multislice computed tomography as a strategic tool for complex percutaneous coronary intervention

Objectives Multislice computed tomography (MSCT) has been currently utilized as a non-invasive diagnostic modality to detect coronary artery disease. We sought to investigate whether preprocedural lesion assessment by MSCT could offer strategic guidance in the setting of elective complex percutaneous coronary intervention (PCI). Methods and Results Twenty-six complex coronary artery lesions in 23 patients were evaluated using 16-row MSCT scanner and an off-line image analysis workstation prior to the PCI. Procedural strategies of PCI were planned based on the morphologic and geometric analysis of the target lesion and vessel. MSCT provided valuable strategic information, which was useful for subsequent PCI procedure. The three-dimensional computed tomography (CT) images allowed us to determine optimal working view angle that best demonstrated the target lesion with least foreshortening. Furthermore, the thin-slab maximum intensity projected CT images of the target lesion served as a preprocedural road map depicting the bends of complex luminal path, vessel geometry and occluded segment of the vessel. As results, procedural success was achieved in all cases with complex lesions including chronic total occlusion. Conclusions Our preliminary results showed that preprocedural lesion and vessel assessment by MSCT provided important additive strategic information that led to successful complex PCI procedures.     

3.0T磁共振冠状动脉成像使用对比剂与不使用对比剂图像质量的定量对比分析

目的：采用定量的方法对比分析3．0T冠状动脉MRA（CMRA）使用和不使用对比剂采集对冠状动脉的显示能力和图像质量。方法：58例患者接受CMRA检查,在CMRA的成像过程中采用了使用（n=28）和不使用（n=30）对比剂采集两种方式。使用Soap-Bubble软件对两种方式采集的CMRA数据进行后处理重建并通过测量冠状动脉各主要分支的长度、直径及血管的锐利度,定量评价CMRA的图像质量。结果使用对比剂采集所获得的CMRA各主要分支的测量值为：长度RCA129mm、LM＋LAD112mm、LCX58mm;直径RCA2．9mm、LM＋LAD2．7mm、LCX2．8mm;血管锐利度RCA65％、LAD55％、LCX48％。不使用对比剂采集的CMRA测量值：长度RCA126mm、LM＋LAD109mm、LCX55mm;直径RCA3．0mm、LM＋LAD2．8mm、LCX3．0mm;血管锐利度RCA58％、LAD52％、LCX45％。统计结果显示二者间的血管锐利度和图像质量评分均存在显著性差异（P〈O．05）,但长度和直径的比较无明显差异（P〉0．05）。结论：CMRA采集过程中使用对比剂具有更好的血管锐利度和图像质量,在CMRA的采集过程中建议尽量使用对比剂采集的方式。