Semiautomatic segmentation and stenosis quantification of 3D contrast-enhanced MR angiograms of the internal carotid artery.

A technique is presented for the segmentation and quantification of stenosed internal carotid arteries (ICAs) in 3D contrast-enhanced MR angiography (CE-MRA). Segmentation with sub-pixel accuracy of the ICA is achieved via level-set techniques in which the central axis serves as the initialization. The central axis is determined between two user-defined points, and minimal user interaction is required. For quantification, the cross-sectional area is measured in the stenosis and at a reference segment in planes perpendicular to the central axis. The technique was applied to 20 ICAs. The variation in measurements obtained by this method in comparison with manual observations was 8.7%, which is smaller than the interobserver variability among three experts (11.0%).     

Preview method for electron-beam CT scanning of the coronary arteries

RATIONALE AND OBJECTIVES: The purpose of this study was to evaluate a method that uses electron-beam computed tomography to obtain the most appropriate starting level for complete imaging of the coronary tree and to compare it with the existing method. A second aim was to evaluate the spatial location of the coronary arteries relative to different anatomic cardiac and chest landmarks. MATERIALS AND METHODS: Two hundred forty consecutive patients were randomly assigned to imaging with either a six-level preview (new) method or the traditional preview method. The accuracy of each preview method to encompass the coronary anatomy was compared. RESULTS: All coronary arteries were included in 3-mm scans obtained starting three levels above the origin of the left main coronary artery. The left anterior descending coronary artery extended 3-9 mm above the left main artery in 33 patients (14%). The coronary arteries were encompassed by scans depicting 72-105 mm; thus, with 3-mm sections, up to 35 scans are necessary to cover the entire coronary tree. No stable relationship between the coronary arteries and the pulmonary artery or carina could be found. CONCLUSION: The six-level preview method that identifies the left main coronary artery and begins 9 mm above this level is the most accurate method for depicting the coronary anatomy. No anatomic landmarks in the heart or chest can be used reliably to identify the position of the coronary arteries in individual patients.     

Spiral phase velocity mapping of left and right coronary artery blood flow: correction for through-plane motion using selective fat-only excitation

PURPOSE: To develop a method of correcting both right and left coronary artery flow velocities for the through-plane motion of the vessel, in order to allow details in the temporal flow profiles to be viewed. MATERIALS AND METHODS: The methods developed use selective excitation and velocity mapping of the epicardial fat surrounding the artery, either in a separate acquisition (temporal resolution = 22 msec) or interleaved with the water-excitation acquisition (temporal resolution = 44 msec) used to determine coronary blood flow velocities. The two methods were compared in 10 right and 13 left coronary arteries in healthy volunteers. RESULTS: For the right coronary arteries, correction for through-plane motion significantly reduces the mean systolic flow velocity (75.3 mm/second vs. 90.0 mm/second, P < 0.01), while the mean diastolic flow velocity is unchanged (96.8 mm/second vs. 94.5 mm/second, P = ns). The resulting profiles are biphasic, with approximately equal flow in systole and diastole. For the left arteries, correction for through-plane motion reduces the mean systolic flow velocity (25.0 mm/second vs. 72.8 mm/second, P < 0.001), resulting in the expected diastolic predominant flow profiles. For the right arteries, there were no significant differences in the mean systolic and mean diastolic velocities after correction with the separate fat-excitation acquisition, and after correction the poorer temporal resolution combined water excitation/fat excitation acquisition. However, for the left coronary arteries, the combined water excitation/fat excitation acquisition resulted in a slight reduction in the mean diastolic velocity (121.5 mm/second vs. 130.9 mm/second, P < 0.05). CONCLUSION: Selective excitation of the surrounding epicardial fat enables through-plane correction of both left and right coronary flow velocities, enabling the temporal details of flow velocity to be viewed.With a combined WE/FE acquisition, this can be performed without extending the study duration; however, the reduced temporal resolution and temporal mismatch of the excitations results in a blunting of rapidly changing flow profiles. As such, it may be less suitable for the left coronary artery, which has a greater range of through-plane motion than the right, and correction using separate WE and FE acquisitions, or the adjacent myocardium, may be preferable.     

外周支架在经皮冠状动脉介入治疗中的应用

目的评价PALMAZ BLUE.014外周支架(简称BLUE支架)在经皮冠状动脉介入治疗(PCI)中的疗效和安全性。方法经冠状动脉造影确诊5例冠心病患者,其参照血管直径≥5.0 mm(简称大冠状动脉),术中采用BLUE支架,共置入5枚,其中前降支3枚,右冠状动脉2枚。结果 5枚支架均顺利置入冠状动脉狭窄段,支架置入术后,残余狭窄≤10%。住院期间及术后随访6~12个月,所有患者均未出现胸痛或胸闷症状,未发生支架内血栓、心肌梗死及再次血管重建。术后6~12个月均复查冠状动脉造影,5枚支架内未见明显再狭窄。结论 BLUE支架用于PCI术,安全性好,疗效满意,可作为大冠状动脉冠心病患者PCI治疗的策略之一。     

Optimal 3D reconstruction of coronary arteries for 3D clinical assessment

A novel method is presented for 3D reconstruction of the coronary arteries. The algorithm refines the point correspondences between the arteries visible in a pair of monoplane X-ray fluoroscopy images acquired at different incidences. Traditional computer vision techniques use the RANSAC methods to discard outliers in a list of corresponding points. However, as these methods work for rigid motion primarily, we introduce a curvature constraint that relates the 2D and 3D Frenet information of the coronary artery centerlines. This constraint takes into account non-rigid movement of the arteries and also serves as a refinement tool to discard potential outlier points. Results show that for synthetic experiments with left-right anterior oblique (LAO/RAO) and posterior-left lateral (PA/LAT) viewing angles, the average 3D RMS errors are respectively 3.1mm and 1.9mm for the RANSAC method, and decrease to 2.8mm and 1.1mm by using our curvature constraint methodology. Similarly, clinical validation is performed on two datasets and the average 2D retroprojection errors are 3.34pixels and 2.24pixels, respectively.     

成人先天性冠状动脉畸形的分类及其发生率

目的 探讨成人冠状动脉(冠脉)造影人群先天性冠脉畸形(CCA)的类型及其发生率.方法 2000年10月～2006年10月共1 520例成人患者行冠脉造影检查,对检出有CCA患者的影像资料进行回顾性分析,并根据CCA解剖学特征进行分类.结果 1 520例成人患者共检出各类CCA 58例,发生率3.82%.冠脉起源和分布异常26例,发生率1.71%;其中前降支和回旋支分别开口于左冠窦14例,左主干或回旋支起源于右冠窦各1例,右冠脉分别起源于升主动脉4例、左冠窦3例和无冠窦1例,单支左冠脉2例.冠脉终止异常11例,均为冠脉瘘,发生率0.72%.冠脉结构异常21例,发生率1.38%,其中心肌桥18例,回旋支发育不良2例,窦房结动脉起源于左室后支1例.本组病例未发现有冠脉间异常交通者.结论 冠脉造影是诊断成人CCA的主要方法之一,按解剖学特征进行分类有助于阐明CCA类型及其发生率.     

Intracoronary MR imaging using a 0.014-inch MR imaging-guidewire: toward MRI-guided coronary interventions

PURPOSE: To validate the feasibility of using a newly designed MR imaging-guidewire (MRIG) to guide angioplasty balloon placement in coronary arteries. MATERIALS AND METHODS: A custom gold/sliver/Nitinol/MP35N-based, 0.014-inch MRIG was manufactured. To test its mechanical performance we used the new MRIG to catheterize the left coronary arteries of three dogs under x-ray fluoroscopy. To further validate the feasibility of using the MRIG to generate intracoronary MR imaging, we positioned the MRIG, along with a dilation-perfusion balloon catheter, into the left coronary arteries of an additional three dogs. Longitudinal and four-chamber views of cine cardiac MR images were obtained using a fast gradient recalled echo (FGRE) sequence (TR/TE/FA = 5.2 msec/1.6 msec/20 degrees , field of view [FOV] = 32 x 32 cm, thickness = 5 mm, space = 2 mm, matrix = 256 x 160, number of excites [NEX] = 0.5, and bandwidth [BW] = 32 kHz). Then three-dimensional (3D) MR coronary angiography of the left coronary arteries was obtained using a fast imaging employing steady-state acquisition (FIESTA) sequence. We subsequently used the MRIG, at a receive-only mode, to generate intracoronary MR images using FGRE (TR/TE/FA = 7.2 msec/3.5 msec/20 degrees , FOV = 18 x 18cm, thickness = 3 mm, space = 0.5 mm, matrix = 256 x 256, NEX = 0.5, and BW = 32 kHz). RESULTS: In all six animals the left main coronary arteries were successfully catheterized. 3D MR imaging displayed left coronary artery branches. Intracoronary MR imaging demonstrated the inflated balloons as a "train track" or a bright, thick ring at different views. CONCLUSION: This study demonstrates the potential of using this newly designed gold/sliver/Nitinol/MP35N-based, 0.014-inch MRIG to catheterize coronary arteries and, thus, generate intracoronary MR imaging with balloon inflation.     

256层CTA评估左冠状动脉分叉角度及其与斑块形成的关系

目的利用256层CT血管成像（CTA）获取正常左侧冠状动脉分叉角度正常值,并探讨分叉角度与左侧冠状动脉斑块形成的潜在关系。方法从我院2011年6月～2012年5月进行冠状动脉CTA检查患者中,选取100例正常冠状动脉图像、100例左侧冠状动脉斑块形成患者图像（支架植入术后复查及搭桥术后复查患者除外）进行回顾性分析,分析结果由四名医生共同确定。结果正常左侧冠状动脉分叉角度为45°～139°,平均值为81．1°;斑块组分叉角度夹角范围为59°～142°,平均值为98．6°,夹角在〉90°时斑块好发。结论MSCT能够无创、清晰显示冠状动脉,左侧冠状动脉分叉角度作为潜在血流动力学因素之一对斑块的形成具有重要影响。     

MSCT冠状动脉造影的临床应用

目的: 评价多层螺旋CT(MSCT)冠状动脉造影效果及其诊断冠状动脉狭窄的价值.材料和方法:65例临床疑诊冠心病患者作MSCT扫描,所有数据获得在一次屏气中完成.利用心电门控技术,将所得原始图像进行重建,分别对左主干(LMA)、左前降支(LAD)、回旋支(LCA)和右冠状动脉(RCA)及其分支的重建图像进行影像学评价;其中45例同时作常规冠状动脉造影(CAG),以造影结果为金指标,将两种方法所得结果进行对比,了解MSCT冠状动脉造影诊断冠脉狭窄的敏感性和特异性.结果:MSCT冠脉钙化积分诊断冠心病的敏感性79.6%,特异性84.9%;65例共260支血管经MSCT成像,228支(87.7%)可用于影像学评价;各节段冠状动脉重建图像,左主干和前降支近中段显示率最高;CAG发现狭窄49支, MSCT发现狭窄44支.MSCT对冠状动脉狭窄诊断的敏感性83.7%,特异性97.7%.结论: 在控制心率的情况下,MSCT冠状动脉造影可作为诊断冠状动脉狭窄的一种无创筛选检查方法.     

High-resolution selective three-dimensional magnetic resonance coronary angiography with navigator-echo technique: segment-by-segment evaluation of coronary artery stenosis

PURPOSE: To investigate the feasibility of high-resolution selective three-dimensional (3D) magnetic resonance coronary angiography (MRCA) in the evaluation of coronary artery stenoses. MATERIALS AND METHODS: In 12 patients with coronary artery stenoses, MRCA of the coronary artery groups, including the coronary segments with stenoses of 50% or greater based on conventional x-ray coronary angiography (CAG), was performed with double-oblique imaging planes by orienting the 3D slab along the major axis of each right coronary artery-left circumflex artery (RCA-LCX) group and each left main trunk-left anterior descending artery (LMT-LAD) group. Ten RCA-LCX and five LMT-LAD MR angiograms were obtained, and the results were compared with those of conventional x-ray angiography. RESULTS: Among 70 coronary artery segments expected to be covered, a total of 49 (70%) segments were fully demonstrated in diagnostic quality. The identification of segmental location of stenoses showed as high an accuracy as 96%. The retrospective analysis for stenosis of 50% or greater yielded the sensitivity, specificity, and accuracy of 80%, 85%, and 84%, respectively. CONCLUSION: Selective 3D MRCA has the potential for segment-by-segment evaluation of major portions of the right and left coronary arteries with high accuracy.     

Comparison of spiral and FLASH phase velocity mapping, with and without breath-holding, for the assessment of left and right coronary artery blood flow velocity

PURPOSE: To develop high temporal resolution coronary artery spiral phase velocity mapping sequences and to compare the results obtained with those from FLASH sequences. MATERIALS AND METHODS: Velocity curves were obtained in eight left and eight right coronary arteries using breath-hold interleaved spiral (BH_SP), free-breathing interleaved spiral (FB_SP), breath-hold segmented FLASH (BH_FL), and free-breathing FLASH (FB_FL) sequences. Spatial resolution, temporal resolution, and acquisition durations (cardiac cycles) were as follows-BH_SP: 0.9 mm x 0.9 mm, 30 msec, 20 cycles; FB_SP: 0.9 mm x 0.9 mm, 42 msec, 100 cycles; BH_FL: 0.9 mm x 1.8 mm, 70 msec (effective), 20 cycles; FB_FL: 0.9 mm x 1.8 mm, 30 msec, 480 cycles. Peak systolic, peak diastolic, and mean velocities were compared between sequences. RESULTS: For left and right arteries, the FB_SP velocity profiles closely followed those from the FB_FL sequence. By comparison, the BH_FL sequence failed to resolve the sharp peaks in the temporal velocity profiles of the right coronary artery, significantly underestimating the peak systolic (88 mm/second vs. 252 mm/second, P < 0.001), peak diastolic (114 mm/second vs. 153 mm/second, P < 0.01), and mean (56 mm/second vs. 93 mm/second, P < 0.001) velocities. For the less mobile left artery, the peak systolic, peak diastolic, and mean velocities were also underestimated by the BH_FL sequence, although this only reached statistical significance for the systolic peak (80 mm/second vs. 135 mm/second, P < 0.01), 142 mm/second vs. 168 mm/second, (P = ns), and 87 mm/second vs. 101 mm/second, (P = ns) respectively. CONCLUSION: We have shown that the FB_SP sequence developed agrees well with the FB_FL sequence, while the study duration is reduced by a factor of 10 for the same spatial resolution. By comparison, the BH_FL sequence underestimates flow velocities, particularly in the more mobile right coronary artery.     

Quantitative parameters of image quality in 64-slice computed tomography angiography of the coronary arteries

We explored quantitative parameters of image quality in consecutive patients undergoing 64-slice multi-detector computed tomography (MDCT) coronary angiography for clinical reasons. Forty-two patients (36 men, mean age 61 +/- 11 years, mean heart rate 63 +/- 10 bpm) underwent contrast-enhanced MDCT coronary angiography with a 64-slice scanner (Siemens Sensation 64, 64 mm x 0.6 mm collimation, 330 ms tube rotation, 850 mAs, 120 kV). Two independent observers measured the overall visualized vessel length and the length of the coronary arteries visualized without motion artifacts in curved multiplanar reformatted images. Contrast-to-noise ratio was measured in the proximal and distal segments of the coronary arteries. The mean length of visualized coronary arteries was: left main 12 +/- 6 mm, left anterior descending 149 +/- 25 mm, left circumflex 89 +/- 30 mm, and right coronary artery 161 +/- 38 mm. On average, 97 +/- 5% of the total visualized vessel length was depicted without motion artifacts (left main 100 +/- 0%, left anterior descending 97 +/- 6%, left circumflex 98 +/- 5%, and right coronary artery 95 +/- 6%). In 27 patients with a heart rate < or = 65 bpm, 98 +/- 4% of the overall visualized vessel length was imaged without motion artifacts, whereas 96+/-6% of the overall visualized vessel length was imaged without motion artifacts in 15 patients with a heart rate > 65 bpm (p < 0.001). The mean contrast-to-noise ratio in all measured coronary arteries was 14.6 +/- 4.7 (proximal coronary segments: range 15.1 +/- 4.4 to 16.1 +/- 5.0, distal coronary segments: range 11.4 +/- 4.2 to 15.9 +/- 4.9). In conclusion, 64-slice MDCT permits reliable visualization of the coronary arteries with minimal motion artifacts and high CNR in consecutive patients referred for non-invasive MDCT coronary angiography. Low heart rate is an important prerequisite for excellent image quality.     

Nonrigid retrospective respiratory motion correction in whole‐heart coronary MRA

A nonrigid retrospective respiratory motion correction scheme is presented for whole‐heart coronary imaging with interleaved acquisition of motion information. The quasi‐periodic nature of breathing is exploited to populate a 3D nonrigid motion model from low‐resolution 2D imaging slices acquired interleaved with a segmented 3D whole‐heart coronary scan without imposing scan time penalty. Reconstruction and motion correction are based on inversion of a generalized encoding equation. Therein, a forward model describes the transformation from the motion free image to the motion distorted k‐space data, which includes nonrigid spatial transformations. The effectiveness of the approach is demonstrated on 10 healthy volunteers using free‐breathing coronary whole‐heart scans. Although conventional respiratory‐gated acquisitions with 5‐mm gating window resulted in an average gating efficiency of 51% ± 11%, nonrigid motion correction allowed for gate‐free acquisitions, and hence scan time reduction by a factor of two without significant penalty in image quality. Image scores and quantitative image quality measures for the left coronary arteries showed no significant differences between 5‐mm gated and gate‐free acquisitions with motion correction. For the right coronary artery, slightly reduced image quality in the motion corrected gate‐free scan was observed as a result of the close vicinity of anatomical structures with different motion characteristics. Magn Reson Med, 2011. © 2011 Wiley Periodicals, Inc.     

冠状动脉内多普勒超声研究冠状动脉血流速度

目的:评价冠状动脉内多普勒超声测量冠脉血流速度的应用价值。材料和方法:利用冠状动脉内多普勒血流钢丝(FloWire) 测量21 例冠状动脉狭窄患者和12 例正常冠状动脉的血流速度。结果:左前降支冠脉狭窄远端的平均最大血流速度(APV) 、舒张期最大血流速度(DPV) 和舒张期与收缩期流速比值(DSVR) 均显著低于正常组测值。结论:应用冠脉内多普勒超声技术可评价正常和冠脉狭窄病变患者的冠脉血流速度,这为定量研究冠脉血流动力学提供了新方法。     

Volumetric coronary angiography using the 256-detector row computed tomography scanner: comparison in vivo and in vitro with porcine models

Purpose: To investigate the feasibility of volumetric cine imaging in human cardiac studies by comparing in vivo and in vitro coronary angiography using a 256-detector row computed tomography (CT) without ECG gating.

Material and Methods: The left and right coronary arteries of two domestic pigs were scanned in vivo and in vitro in cine mode using the 256-detector row CT. The device scanned approximately 100 mm in the cranio-caudal direction with one rotation, with a slice thickness of 0.5 mm.

Results: The coronary arteries could be observed to the third-degree branches in vitro, but could be visualized clearly only to the proximal portion (first-degree or second-degree branches) in vivo.

Conclusion: Application of cardiac volumetric cine imaging with 256-detector row CT may be a promising means of obtaining diagnostic information and has potential for adoption to human studies.     

多层螺旋CT在心肌桥诊断中的应用及优势

目的 探讨多层螺旋CT(MSCT)在心肌桥中的诊断能力.方法 对51例临床怀疑为冠状动脉粥样硬化性心脏病的患者进行了MSCT、常规冠状动脉造影(CAG)以及血管内超声检查(将后2种检查方法统称为创伤性技术),共82支冠状动脉,其中的80支冠状动脉无明显伪影,可供评价.分别统计MSCT对心肌桥检出的敏感度、特异度和准确度.观察者间的一致件检验采用Cohen Kappa检验方法.结果CAG及血管内超声共发现26例心肌桥,所有心肌桥均发生于左前降支中段附近.MSCT正确检出26例前降支心肌桥巾的23例,其敏感度88%(23/26),特异度96%(52/54),准确度94%(75/80),2名医师对心肌桥的检出Kappa值为0.62.MSCT尚检出2例心肌桥,为创伤性技术所漏诊.将创伤性技术和MSCT综合结果作对照,则MSCT心肌桥检出的敏感度、特异度和准确度分别为89%(25/28)、91%(21/23)和90%(46/51).结论MSCT作为一种无创性成像方法应用于心肌桥的诊断,方法可行,结果可靠.     

A fast 3D approach for coronary MRA.

Two-dimensional (2D)-breath-hold coronary magnetic resonance angiography (MRA) has been shown to be a fast and reliable method to depict the proximal coronary arteries. Recent developments, however, allow for free-breathing navigator gated and navigator corrected three-dimensional (3D) coronary MRA. These 3D approaches have potential for improved signal-to-noise ratio (SNR) and allow for the acquisition of adjacent thin slices without the misregistration problems known from 2D approaches. Still, a major impediment of a 3D acquisition is the increased scan time. The purpose of this study was the implementation of a free-breathing navigator gated and corrected ultra-fast 3D coronary MRA technique, which allows for scan times of less than 5 minutes. Twelve healthy adult subjects were examined in the supine position using a navigator gated and corrected ECG triggered ultra-fast 3D interleaved gradient echo planar imaging sequence (TFE-EPI). A 3D slab, consisting of 20 slices with a reconstructed slice thickness of 1.5 mm, was acquired with free-breathing. The diastolic TFE-EPI acquisition block was preceded by a T2prep pre-pulse, a diaphragmatic navigator pulse, and a fat suppression pre-pulse. With a TR of 19 ms and an effective TE of 5.4 ms, the duration of the data acquisition window duration was 38 ms. The in-plane spatial resolution was 1.0-1.3 mm*1.5-1.9 mm. In all cases, the entire left main (LM) and extensive portions of the left anterior descending (LAD) and right coronary artery (RCA) could be visualized with an average scan time for the entire 3D-volume data set of 2:57 +/- 0:51 minutes. Average contiguous vessel length visualized was 53 +/- 11 mm (range: 42 to 75 mm) for the LAD and 84 +/- 14 mm (range: 62 to 112 mm) for the RCA. Contrast-to-noise between coronary blood and myocardium was 5.0 +/- 2.3 for the LM/LAD and 8.0 +/- 2.9 for the RCA, resulting in an excellent suppression of myocardium. We present a new approach for free-breathing 3D coronary MRA, which allows for scan times superior to corresponding 2D coronary MRA approaches, and which takes advantage of the enhanced SNR of 3D acquisitions and the post-processing benefits of thin adjacent slices. The robust image quality and the short average scanning time suggest that this approach may be useful for screening the major coronary arteries or identification of anomalous coronary arteries. J. Magn. Reson. Imaging 1999;10:821-825.     

A dual-projection respiratory self-gating technique for whole-heart coronary MRA

PURPOSE: To investigate the accuracy of a dual-projection respiratory self-gating (DP-RSG) technique in dynamic heart position measurement and its feasibility for free-breathing whole-heart coronary MR angiography (MRA). MATERIALS AND METHODS: A DP-RSG method is proposed to enable accurate direct measurement of heart position by acquiring two whole-heart projections. On 14 volunteers we quantitatively evaluated the efficacy of DP-RSG by comparison with diaphragmatic navigator (NAV) and single-projection-based respiratory self-gating (SP-RSG) methods. For DP-RSG we also compared center-of-mass and two profile-matching algorithms in deriving heart motion. Coronary imaging was conducted on eight volunteers based on retrospective gating to preliminarily validate the effectiveness of DP-RSG for whole-heart coronary MRA. Comparison of vessel delineation was performed between images reconstructed using different gating methods. RESULTS: The quantitative evaluation shows that DP-RSG more accurately tracks heart motion than NAV with all gating window (GW) values and SP-RSG approaches with GW>or=2.5 mm and profile-matching algorithms are more reliable for motion derivation than center-of-mass calculations with GW>or=1.0 mm. Whole-heart coronary MRA studies demonstrate the feasibility of using DP-RSG to improve overall delineation of the coronary arteries. CONCLUSION: DP-RSG is a promising approach to better resolve respiratory motion for whole-heart coronary MRA compared to conventional NAV and SP-RSG.     

多层螺旋CT对先天性右冠状动脉起始变异的评价

目的 以常规X线冠状动脉造影（CAG）为标准，评价16层螺旋CT在鉴别右冠状动脉（RCA）异常起源和异常行程中的价值。方法 回顾性分析8例先天性RCA变异患者的多层螺旋CT造影（MSCTA）表现，其中7例有CAG资料。对比分析两者在显示RCA异位开口和异常行程方面的差异。仿真内镜技术用于评价异位开口及其与邻近正常冠状动脉开口的关系。采用多平面重组（MPR）、曲面多平面重组（CMPR）、最大密度投影（MIP）、容积成像（VR）重组方法评价冠状动脉的异常行径及其与邻近大血管的关系。CAG所显示的RCA，至少有2个不同的视角用于评价其起源和行程。结果 8例患者变异的RCA全部为MSCTA所显示。其中6例患者的RCA起源于左冠状动脉窦，1例起源于左主冠状动脉的末端，另1例则起源于扩大前移的后冠窦。所有异常开口均未见狭窄。8支异常冠状动脉均穿过主动脉根部和肺动脉或右室流出道的司隙。7例CAG则仅5例显示异常。结论 MSCTA显示先天性变异的RCA明显优于CAG，凡疑为冠状动脉变异的患者，可首选非创伤性的16层MSCTA检查。     

Quantification of coronary arterial stenoses in CTA using fuzzy distance transform

Quantification of coronary arterial stenoses is useful for the diagnosis of several coronary heart diseases. Being noninvasive, economical and informative, computed tomographic angiography (CTA) has become a common modality for monitoring disease status and treatment effects. Here, we present a new method for detecting and quantifying coronary arterial stenosis in CTA using fuzzy distance transform (FDT) approach and a new coherence analysis of observed data for computing expected local diameter. FDT allows computing local depth at each image point in the presence of partial voluming and thus, eliminates the need for binarization, commonly, associated with inclusion of additional errors. In the current method, coronary arterial stenoses are detected and their severities are quantified by analyzing FDT values along the medial axis of an arterial tree obtained by its skeletonization. A new skeletal pruning algorithm has been developed toward improving the quality of medial axes and thereby, enhancing the accuracy of stenosis detection and quantification. Further, we have developed a new method to estimate “expected diameter” along a given arterial branch using a new coherence analysis of observed diameter values along the branch. The overall method is completed in the following steps - (1) fuzzy segmentation of coronary artery in CTA, (2) FDT computation of coronary arteries, (3) medial axis computation, (4) estimation of observed and expected diameters along arteries and (5) detection of stenoses and quantification of arterial blockage. The performance of this method has been quantitatively evaluated on a realistic coronary artery phantom dataset with randomly simulated stenoses and the results have been compared with a binary distance transform based and a conventional binary algorithm. The method has also been applied on a clinical CTA dataset from thirteen heart patients and the results have been compared with an expert's quantitative assessment of stenoses. Results of the phantom experiment indicate that the new method (error: 0.53%) is significantly more accurate as compared to both binary distance transform based (error 2.11%) and conventional binary (error 3.71%) methods. Also, the results of the clinical study indicate that the new FDT-based method (kappa coefficient = 87.9%) is highly in agreement with the expert's assessments and, in this respect, outperforms the other two methods (kappa coefficients = 75.2% and 69.5%).