An interactive software module for visualizing coronary arteries in CT angiography

Object

A new software module for coronary artery segmentation and visualization in CT angiography (CTA) datasets is presented, which aims to interactively segment coronary arteries and visualize them in 3D with maximum intensity projection (MIP) and volume rendering (VRT).

Materials and Methods

The software was built as a plug-in for the open-source PACS workstation OsiriX. The main segmentation function is based an optimized “virtual contrast injection” algorithm, which uses fuzzy connectedness of the vessel lumen to separate the contrast-filled structures from each other. The software was evaluated in 42 clinical coronary CTA datasets acquired with 64-slice CT using isotropic voxels of 0.3–0.5 mm.

Results

The median processing time was 6.4 min, and 100% of main branches (right coronary artery, left circumflex artery and left anterior descending artery) and 86.9% (219/252) of visible minor branches were intact. Visually correct centerlines were obtained automatically in 94.7% (321/339) of the intact branches.

Conclusion

The new software is a promising tool for coronary CTA post-processing providing good overviews of the coronary artery with limited user interaction on low-end hardware, and the coronary CTA diagnosis procedure could potentially be more time-efficient than using thin-slab technique.     

冠状动脉CT血管成像在自发冠状动脉壁内血肿患者随访中的应用

目的:探讨冠状动脉(冠脉)CT血管成像(CTA)在自发冠脉壁内血肿患者随访中的应用价值.方法:选择复旦大学附属中山医院心内科2015年1月1日至2018年12年31日收治的接受冠脉CTA复查的10例自发冠脉壁内血肿患者.对比初始冠脉造影和随访冠脉CTA影像,测量病变处冠脉管腔直径并进行比较.结果:10例患者共有11根冠...     

3D MR coronary angiography: optimization of the technique and preliminary results

Objective: Current clinical full MR angiography with multiple breathhold multiple thin slab acquisition (MTS) is difficult and arduous. This study describes the optimisation of the whole heart free – breathing balanced turbo field echo (B-TFE) protocol. A high-resolution image of the whole heart is produced in less or comparable time to MTS acquisition and allows for reconstruction afterwards to visualise the individual coronary arteries. The scan is easily performed because the volume has to be targeted only once.Design and setting: Eighteen healthy adults without a history of cardiovascular disease underwent free-breathing 3D MR angiography with the B-TFE protocol. The whole-heart data set was reformatted in identical orientations in all subjects to visualise the major coronary arteries.Main outcome measures: Vessel length, signal and contrast to noise ratio were determined and compared for each vessel.Results: Mean visible vessel lengths were 116 mm for the right, 102 mm for the left main and left descending and 76 mm for the left circumflex coronary artery. The average signal to noise ratio was 7.5 and contrast to noise ratio was 4.9. Because of the need for synchronised cardiac and respiratory triggering the coronaries could not be judged in 25% of the subjects.Conclusions: The optimised B-TFE protocol had equal judgeability and vessels could be judged over longer contiguous distances compared to earlier implementations of the B-TFE protocol. We conclude whole heart free breathing navigator-gated and slice-tracked 3D coronary MR angiography with use of the adjusted B-TFE protocol is possible, but still suboptimal for clinical use.     

Detection of coronary stenoses with contrast enhanced, three-dimensional free breathing coronary MR angiography using the gadolinium-based intravascular contrast agent gadocoletic acid (B-22956).

PURPOSE: To determine the diagnostic value of the intravascular contrast agent gadocoletic acid (B-22956) in three-dimensional, free breathing coronary magnetic resonance angiography (MRA) for stenosis detection in patients with suspected or known coronary artery disease. METHODS: Eighteen patients underwent three-dimensional, free breathing coronary MRA of the left and right coronary system before and after intravenous application of a single dose of gadocoletic acid (B-22956) using three different dose regimens (group A 0.050 mmol/kg; group B 0.075 mmol/kg; group C 0.100 mmol/kg). Precontrast scanning followed a coronary MRA standard non-contrast T2 preparation/turbo-gradient echo sequence (T2Prep); for postcontrast scanning an inversion-recovery gradient echo sequence was used (real-time navigator correction for both scans). In pre- and postcontrast scans quantitative analysis of coronary MRA data was performed to determine the number of visible side branches, vessel length and vessel sharpness of each of the three coronary arteries (LAD, LCX, RCA). The number of assessable coronary artery segments was determined to calculate sensitivity and specificity for detection of stenosis > or = 50% on a segment-to-segment basis (16-segment-model) in pre- and postcontrast scans with x-ray coronary angiography as the standard of reference. RESULTS: Dose group B (0.075 mmol/kg) was preferable with regard to improvement of MR angiographic parameters: in postcontrast scans all MR angiographic parameters increased significantly except for the number of visible side branches of the left circumflex artery. In addition, assessability of coronary artery segments significantly improved postcontrast in this dose group (67 versus 88%, p < 0.01). Diagnostic performance (sensitivity, specificity, accuracy) was 83, 77 and 78% for precontrast and 86, 95 and 94% for postcontrast scans. CONCLUSIONS: The use of gadocoletic acid (B-22956) results in an improvement of MR angiographic parameters, asssessability of coronary segments and detection of coronary stenoses > or = 50%.     

Comparison of radial and Cartesian imaging techniques for MR coronary angiography.

BACKGROUND: Magnetic resonance coronary angiography (MRCA) has traditionally been performed using a Cartesian k-space data acquisition scheme. Radial k-space sampling is known to be less sensitive to motion artifacts. Thus, potential improvements may be achieved with radial k-space data acquisition using steady state free precession (SSFP) techniques. We directly compared SSFP three-dimensional (3D)-MRCA using radial and Cartesian data acquisition. METHODS: Forty-four consecutive patients with suspected coronary artery disease underwent free-breathing, navigator-corrected MRCA of the left or right coronary artery using SSFP (TR/TE/flip angle: 4.5 ms/2.3 ms/90 degrees) with radial and again with Cartesian k-space filling. Quantitative MRCA was performed with a dedicated multiplanar reformatting software to determine: visual score for image quality (low=1, high=4), vessel sharpness, visible vessel length, number of visible side branches, and average vessel diameter. Diagnostic accuracy for detection of > or = 50% coronary artery stenosis was calculated in comparison to invasive X-ray angiography. RESULTS: Radial data acquisition resulted in a significant (p<0.01) increase in vessel sharpness (55.6+/-7.2% vs. 45.9+/-7.0%) but a decrease in average vessel diameter (2.6+/-0.5 mm vs. 3.0+/-0.4 mm), number of visible side branches (2.1+/-1.1 vs. 3.0+/-1.7) and number of assessable coronary artery segments (66% vs. 73%) compared to Cartesian approach. There was no significant difference regarding the diagnostic accuracy (80.8% vs. 83.9%), the visual score (2.6+/-0.9 vs. 3.0+/-0.9) and the visible vessel length (92.1+/-36.0 mm vs. 99.9+/-32.4 mm). CONCLUSIONS: MRCA with radial k-space sampling appears to be on a par with Cartesian approach with respect to the diagnostic performance in an unselected patient population. Nevertheless, with current implementations, radial sampling is inferior to Cartesian sampling regarding the visualization of side branches despite better vessel sharpness.     

Reproducibility of free-breathing cardiovascular magnetic resonance coronary angiography.

OBJECTIVE: Contemporary free-breathing non contrast enhanced cardiovascular magnetic resonance angiography (CMRA) was qualitatively and quantitatively evaluated to ascertain the reproducibility of the method for coronary artery luminal dimension measurements. SUBJECTS AND METHODS: Twenty-two healthy volunteers (mean age 32 +/- 7 years, 12 males) without coronary artery disease were imaged at 2 centers (1 each in Europe and North America) using navigator-gated and corrected SSFP CMRA on a commercial whole body 1.5T System. Repeat images of right (RCA, n = 21), left anterior descending (LAD, n = 14) and left circumflex (LCX, n = 14) coronary arteries were obtained in separate sessions using identical scan protocol and imaging parameters. True visible vessel length, signal-to-noise (SNR), contrast-to-noise ratios (CNR) and the average luminal diameter over the first 4 cm of the vessel were measured. Intra-observer, inter-observer and inter-scan reproducibility of coronary artery luminal diameter were determined using Pearson's correlation, Bland-Altman analysis and intraclass correlation coefficients (ICC). RESULTS: CNR, SNR and the mean length of the RCA, LAD and LCX imaged for original and repeat scans were not significantly different (all p > 0.30). There was a high degree of intra-observer, inter-observer and inter-scan agreements for RCA, LAD and LCX luminal diameter respectively on Bland-Altman and ICC analysis (ICC's for RCA: 0.98. 0.98 and 0.86; LAD: 0.89, 0.89 and 0.63; LCX: 0.95, 0.94 and 0.79). CONCLUSION: In a 2-center study, we demonstrate that free-breathing 3D SSFP CMRA can visualize long continuous segments of coronary vessels with highly reproducible measurements of luminal diameter.     

Potential intrinsic error of noninvasive coronary angiography.

PURPOSE: With current noninvasive techniques compromises have to be accepted for coronary imaging, e.g., partial coverage of the coronary artery tree. The aim of the study was to estimate the potential intrinsic error of partial coverage from a database of invasive angiograms. METHODS AND RESULTS: The localization and severity of coronary artery stenoses and, if percutaneous coronary intervention (PCI) was performed, the balloon and stent size were extracted from a large database of 21,335 selective coronary angiograms. Of stenoses with >50% diameter reduction, 31.4% were located in distal segments and minor side branches, constituting 28.8% of interventional treatment. In 5% of patients undergoing their first invasive angiogram, the most proximal relevant stenosis was found in a distal segment or minor side branch. Most interventions (83.5%) were performed in main coronary artery segments. CONCLUSION: Coronary artery stenoses were found and interventional treatment performed in all coronary segments. Therefore, noninvasive coronary imaging of only proximal and medial segments and major side branches is an inadequate strategy for complete diagnosis or as a guide to therapeutic decisions. However, the currently available noninvasive techniques allow the detection of relevant stenoses in 95% of patients with suspected coronary artery disease (CAD) to prepare for further invasive diagnostic and therapeutic planning.     

The DICOM image formatting standard: its role in echocardiography and angiography

Electron beam tomography (EBT) has been shown to permit non-invasive imaging of the coronary arteries after intravenous injection of contrast agent and 3-dimensional reconstruction. We compared the vessel diameters in EBT reconstructions to quantitative coronary angiography (QCA). 10 patients were investigated by EBT and QCA. 3-dimensional EBT reconstructions (shaded surface display) were performed after acquisition of 40 axial cross-sections of the heart with 3 mm slice thickness (1 mm overlap) which were obtained triggered to the ECG in breathhold following intravenous injection of 120–160 ml of contrast agent. A fixed lower reconstruction threshold of 80 HU was used to selectively visualize the contrast-enhanced coronary artery lumen. At 60 sites in the coronary artery system, the vessel diameters measured in the EBT reconstructions were compared to the diameters found in quantitative analysis of the patients' coronary angiograms. The correlation coefficient of the vessel diameters in EBT and QCA was 0.83. Mean vessel diameters were not significantly different in EBT and QCA (3.06±0.93 vs. 2.97±0.94 mm). However, very small vessel diameters tended to be underestimated in the EBT reconstructions, which was due to the partial volume effect. If only vessel diameters measured in the left main or left anterior descending coronary artery were compared to QCA, the correlation increased to 0.87, since these vessel segments are less prone to artifacts in the EBT investigation. Vessel diameters in EBT and QCA correlate reasonably well. Due to partial volume effects, the diameter of very small vessels and stenotic segments tends to be underestimated by EBT.     

Three-dimensional, time-resolved motion of the coronary arteries.

BACKGROUND: Coronary artery motion can decrease image quality during coronary magnetic resonance angiography and computed tomography coronary angiography. PURPOSE: To characterize the three-dimensional motion of the coronary arteries along the entire vessel length and to identify the temporal location and duration of periods of relatively low cardiac motion in patients with coronary artery disease. METHODS: Archived digital, biplane x-ray angiography films acquired at 30 frames per second with simultaneous electrocardiogram recording were reviewed for 15 patients with coronary artery disease. The right coronary (RCA), left anterior descending (LAD), and left circumflex (LCX) arteries were divided into proximal, mid, and distal segments. The displacement and velocity of a point in each segment were calculated throughout the heart cycle. Time-dependent, three-dimensional motion of each segment on each vessel was determined. Periods of the heart cycle during which maximal displacement was less than 1 mm or 0.5 mm per frame for each artery were determined. RESULTS: A period lasting an average of 187 msec was seen during mid-diastole (72+/-5% of the cardiac cycle) in which all three coronary arteries studied had relatively little motion. This period of quiescence was consistent along the length of the arteries. Although the amount of motion did vary along the length of the arteries, there was no difference in the timing of rest periods in the proximal, mid, and distal segments using a < 1 mm per frame threshold. The periods of low motion were significantly reduced in length and often altogether eliminated when the 0.5 mm per frame threshold was used.     

冠状动脉造影及支架植入术在冠状动脉狭窄中的应用

目的：探讨冠状动脉造影术对冠状动脉狭窄的诊断价值和FTCA、支架植入术对冠状动脉狭窄病人的治疗效果。方法：回顾性分析冠状动脉造影143例，其中的54例76支病变冠状动脉植入支架59枚，包括前降支25枚、回旋支12枚和右冠状动脉22枚。结果：冠状动脉狭窄发生率依次为前降支、右冠、回旋支及其他分支。老年人冠状动脉狭窄的严重程度及多支病变狭窄的发生率较中青年明显增加。狭窄血管经PTCA及支架植入后血供明显改善，但仍有可能发生再狭窄。结论：冠状动脉造影术是诊断冠状动脉狭窄的金标准，经皮冠状动脉内支架植入术是治疗冠心病的有效方法。     

Multifocal coronary artery myocardial bridging involving the right coronary and left anterior descending arteries detected by ECG-gated 64 slice multidetector CT coronary angiography

Myocardial bridging is a congenital condition in which a segment of a major epicardial coronary artery has an intramyocardial course. Myocardial bridging is usually confined to a single vessel (typically the mid segment of the left anterior descending artery) and is usually asymptomatic, however, bridging may be associated with chest pain, myocardial infarction, or sudden cardiac death. While more commonly identified at autopsy, myocardial bridging is occasionally diagnosed by coronary angiography with identification of concomitant myocardial bridging involving both the left and right coronary arteries appearing to be uncommon. We present three patients presenting with atypical chest pain symptoms in whom concomitant right coronary artery and left anterior descending artery myocardial bridging was identified by ECG gated multidetector computed tomography (MDCT).     

Determination of optimal viewing regions for X-ray coronary angiography based on a quantitative analysis of 3D reconstructed models

Current expert-recommended views for coronary angiography are based on heuristic experience and have not been scientifically studied. We sought to identify optimal viewing regions for first and second order vessel segments of the coronary arteries that provide optimal diagnostic value in terms of minimizing vessel foreshortening and overlap. Using orthogonal 2D images of the coronary tree, 3D models were created from which patient-specific optimal view maps (OVM) allowing quantitative assessment of vessel foreshortening and overlap were generated. Using a novel methodology that averages 3D-based optimal projection geometries, a universal OVM was created for each individual coronary vessel segment that minimized both vessel foreshortening and overlap. A universal OVM model for each coronary segment was generated based on data from 137 patients undergoing coronary angiography. We identified viewing regions for each vessel segment achieving a mean vessel foreshortening value of 5.8 ± 3.9% for the left coronary artery (LCA) and 5.6 ± 3.6% for the right coronary artery (RCA). The overall mean overlap values achieved were 8.7 ± 7.9% for the LCA and 4.6 ± 3.2% for the RCA. This scientifically-based OVM evaluation of coronary vessel segments provides the means to facilitate acquisitions during coronary angiography and interventions that minimize imaging inaccuracies related to foreshortening and overlap, improving the accuracy, efficiency, and safety of diagnostic and interventional coronary procedures.     

屏气法三维磁共振冠状动脉血管造影诊断先天性冠状动脉起源畸形

目的探讨屏气法三维磁共振冠状动脉造影(3D MRCA)显示畸形冠状动脉与主动脉根部、右心室流出道关系的可行性及价值.方法 5名临床拟诊患者、1例志愿者接受MRCA检查,以屏气法三维稳态进动快速成像(3D true-FISP)梯度回波序列采集图像,获得左、右冠状动脉图像,分析畸形冠状动脉近段与冠状动脉窦(Valsalva窦)、右心室流出道的位置关系.结果 6例MRCA均明确诊断先天性冠状动脉起源畸形,畸形血管近段均走行于主动脉根部与右心室流出道之间.结论屏气法3D MRCA可明确诊断先天性冠状动脉起源畸形,显示畸形冠状动脉近段的走行路经,是一种可行的影像诊断方法.     

Assessment of vasoreactivity using videodensitometry coronary angiography

Background: Previous studies demonstrated that the dysfunction of vasomotor tone (VT) is closely linked to the development of atherosclerosis and it is considered important in the very early stages of atherogenesis. Currently, the evaluation of VT relies on lumen changes in response to vasoactive stimuli using quantitative coronary angiography (QCA) based on geometric edge detection (ED). However, using ED for measuring lumen diameters is inherently associated with large uncertainties. Videodensitometry (VD) methods have important advantages over ED for QCA. The objective of this study was to investigate the reliability of VD and ED techniques in determining the effect of nitroglycerin (NTG) on cross-sectional area (CSA) and volume changes in a swine animal model for evaluating coronary vasoreactivity. Methods and results: Coronary angiography was performed on four anesthetized swine. CSA and volume were measured in the left anterior descending (LAD) coronary artery using VD before and after intracoronary injection of 0.3 mg of NTG. CSA was also calculated using standard QCA based on ED. The average CSA changes in the proximal, middle and distal branches measured using VD were 23.83% (±10.76%), 30.78% (±18.39%), and 27.34% (±36.53%), respectively. Similarly, the average CSA changes in the proximal, middle, and distal branches measured using ED were 15.02% (±36.38%), 22.02% (±26.12), and 38.00% (±48.31%), respectively. The average lumen volume change measured using VD was 29.79% (±14.79%). In order to evaluate the relative reliability of the techniques, the significance of deviation (SOD) was calculated, which is the ratio of the change after NTG and the measurement error. The average SOD for CSA for all the branches based on VD and ED were 1.86 and 0.69, respectively. The SOD for volume measurement was 2.78. Conclusions: Lumen changes measured by VD showed substantial improvement in reliability when compared to the ED. Moreover, VD can be used to measure substantially smaller changes in lumen dimension in response to vasoactive stimuli than the standard QCA based on ED. Finally, VD allows the measurement of arterial volume, which is not possible with ED.     

Accuracy and rate of coronary artery segment visualization with CT angiography for the non-invasive detection of coronary artery stenoses

Objectives To evaluate CT coronary angiography (CTA) when compared with catheter coronary angiography (CCA), for the detection of coronary artery stenoses and rate of optimal coronary artery segment visualization. Method Retrospective, two-center study enrolling 26 patients who underwent CCA and ECG-gated 16-detector CTA (slice thickness 0.6 mm; rotation 500 ms). Results and conclusion 283 segments were available for postprocessing. Sensitivity, specificity, and positive predictive value were, respectively, 80, 100, and 100%, for detecting more than 50% luminal stenoses, when optimally visualized segments were considered, in comparison to CCA. Negative predictive value was excellent (98%). Rate of non-optimally visualized coronary segments was 26%. Most clinical benefits of coronary CT angiography should probably be obtained when it is performed to exclude significant stenoses on selected populations of patients with a low pre-test probability of severe coronary artery disease, and under optimal conditions of controlled heart rate and minimal presence of calcium.     

CT angiography in highly calcified arteries: 2D manual vs. modified automated 3D approach to identify coronary stenoses

Background Two-dimensional axial and manually-oriented reformatted images are traditionally used to analyze coronary data provided by multidetector-row computed tomography angiography (MDCTA). While apparently more accurate in evaluating calcified vessels, 2D methods are time-consuming compared with automated 3D approaches. The purpose of this study was to evaluate the performance of a modified automated 3D approach (using manual vessel isolation and different window and level settings) in a population with high calcium scores who underwent coronary half-millimeter 16-detector-row CT angiography (16×0.5-MDCTA).Methods ECG-gated 16×0.5-MDCTA (16×0.5 mm cross-sections, 0.35×0.35×0.35 mm³ isotropic voxels, 400 ms rotation) was performed after injection of iopamidol (120-ml, 300 mg/ml) in 19 consecutive patients (11 male, 62±10 years-old). Native arteries were independently evaluated for ≥50%-stenoses using both manual 2D and modified automated 3D approaches. Stents and bypass grafts were excluded. Conventional coronary angiography was visually analyzed by 2 observers.Results Median Agatston calcium score was 434. Sensitivities, specificities, positive and negative predictive values for detection of ≥50% coronary stenoses using the 2D and modified 3D approaches were, respectively: 74%/63%, 76%/80%, 45%/34%, and 91%/93% (p=NS for all comparisons). Overall diagnostic accuracies were 75 and 78%, respectively (p=NS). Uninterpretable vessels were, respectively: 37% (77/209) and 35% (73/209) – p=NS. Time to analyze a single study was 160±23 and 53±11 min, respectively (p<0.01).Conclusions This modified automated 3D approach is equivalent to and significantly less time consuming than the traditional manual 2D method for evaluation of ≥50%-stenoses by 16×0.5-MDCTA in native coronary arteries of patients with high calcium scores.     

Dual-source CT coronary angiography without heart rate or rhythm control in comparison with conventional coronary angiography

To explore the value of dual-source CT angiography (DSCTA) in diagnosing coronary artery stenosis (CAS) without heart rate or rhythm control. Eighty-nine patients with different heart rates/rhythms underwent both DSCTA and conventional coronary angiography (CCA) in 1 week. The diagnostic quality of normal coronary arteries and stenosed segments using DSCTA and CCA were analyzed, respectively, with CCA as the gold standard. Kappa test was used to assess the intermodality agreement between DSCTA and CCA in grading CAS. The value of DSCTA in diagnosing CAS (>50% stenoses) were analyzed as well. The total evaluable rate of DSCTA in detecting coronary arteries was 98.8%. No significant difference between evaluable rates from different groups of heart rate (χ ² = 1.745, P > 0.05) was found. Sensitivity, specificity, positive and negative predictive values of DSCTA in detecting CAS and >50% stenoses were 97.9, 96.8, 89.5, 99.4 and 97.2, 95.5, 80.3, 99.4%, respectively; The inter-modality agreement between DSCTA and CCA in grading CAS was found to be excellent (k = 0.856, P < 0.01). DSCTA provides high accuracy and reliability for evaluation of CAS in a high suspected patient group without heart rate/rhythm control. It can be used as a powerful primary tool for the detection of CAS and a potential substitute of CCA.     

经桡动脉途径行冠状动脉造影和腔内成形术及其并发症处理

目的:探讨经桡动脉途径行冠状动脉造影及介入治疗及并发症处理方法。方法:对486例冠状动脉病变患者进行选择性冠状动脉造影,术前进行Allen试验阳性后选右侧桡动脉为穿刺点,行左右冠状动脉造影。结果:造影示冠状动脉正常85例(其中肌桥25例),单支病变192例,双支血管病变137例,多支病变72例。植入支架378例,其中329例(87.04%)经桡动脉途径手术成功,另外49例改经股动脉途径手术成功。术中、术后并发症较少,术后桡动脉搏动正常。结论:经桡动脉途径行经皮冠状动脉造影及介入治疗是安全、有效,是股动脉穿刺冠状动脉造影介入治疗的有效补充。     

3D Assessment of myocardial perfusion parameter combined with 3D reconstructed coronary artery tree from digital coronary angiograms

In patients with coronary artery disease coronary angiography plays an important role in the clinical decision-making process. However, it has been recognized that no simple relation exists between the visually or quantitatively evaluated severity of coronary artery stenoses and its effects on regional myocardial perfusion. This paper describes for the first time the development and application of a 3D technique that visualizes and quantifies regional myocardial perfusion parameters from biplane coronary angiograms by using the impulse response analysis technique. The 3D reconstructed coronary tree is automatically superimposed on the 3D perfusion image to generate and visualize an ‘integrated’ 3D image. The preliminary results in patients with critical coronary artery stenoses indicate that our combined 3D fusion image provides flow information from the major coronary arteries. This 3D fusion image may provide useful information in the management of patients with coronary artery disease.     

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.