Coronary Arterial Tree Research Articles

Influence of contrast agent dispersion on bolus-based MRI myocardial perfusion measurements: A computational fluid dynamics study.

Bolus-based dynamic contrast agent (CA) perfusion measurements of the heart are subject to systematic errors due to CA bolus dispersion in the coronary arteries. To better understand these effects on quantification of myocardial blood flow and myocardial perfusion reserve (MPR), an in-silico model of the coronary arteries down to the pre-arteriolar vessels has been developed. In this work, a computational fluid dynamics analysis is performed to investigate these errors on the basis of realistic 3D models of the left and right porcine coronary artery trees, including vessels at the pre-arteriolar level. Using advanced boundary conditions, simulations of blood flow and CA transport are conducted at rest and under stress. These are evaluated with regard to dispersion (assessed by the width of CA concentration time curves and associated vascular transport functions) and errors of myocardial blood flow and myocardial perfusion reserve quantification. Contrast agent dispersion increases with traveled distance as well as vessel diameter, and decreases with higher flow velocities. Overall, the average myocardial blood flow errors are -28% ± 16% and -8.5% ± 3.3% at rest and stress, respectively, and the average myocardial perfusion reserve error is 26% ± 22%. The calculated values are different in the left and right coronary tree. Contrast agent dispersion is dependent on a complex interplay of several different factors characterizing the cardiovascular bed, including vessel size and integrated vascular length. Quantification errors evoked by the observed CA dispersion show nonnegligible distortion in dynamic CA bolus-based perfusion measurements. We expect future improvements of quantitative perfusion measurements to make the systematic errors described here more apparent.

The CatLet score: a new coronary angiographic scoring tool accommodating the variable coronary anatomy for the first time.

The SYNTAX score for decision makings or outcome predictions in coronary artery disease does not account for the variations in the coronary anatomy, which is a clear fallacy for patients with less typical anatomy than suggested by the SYNTAX score. The current study aimed to derive a new coronary angiographic scoring system accommodating the variability in the coronary anatomy. The 17-myocardial segment model and laws of competitive blood supply and flow conservation were utilized to derive this new scoring system. We obtained 6 types of RCA dominance, 3 types of diagonal size and 3 types of left anterior descending artery (LAD) length, which together resulted in a total of 54 patterns of coronary artery circulation to account for the variability in the coronary anatomy among individuals. A Coronary Artery Tree description and Lesion EvaluaTion (CatLet) angiographic scoring system has been designed based on the above-mentioned reclassification scheme (htpp://www.catletscore.com, IE browser is required to run this calculator). This new CatLet angiographic scoring system accommodated the variability in the coronary anatomy and standardized the collection of the coronary angiographic data, which could facilitate the comparison and exchange of these data between different catheter labs. Its utility for predicting the clinical outcomes and standardizing the angiographic data collection will be investigated in a series of clinical trials enrolling "all-comers" with coronary artery disease (CAD).

Finet\u2019s Law as a Special Case of the Generalised Murray\u2019s Law

A thorough knowledge of statistical properties of the coronary artery tree is very important in cardiology. We present generalised form of Murray’s law—the first law that described the relationship between vessel diameters in bifurcation. We show that other frequently used laws: Huo-Kassab and Finet’s rules are the special cases of its generalised form. We show theoretically that the Finet’s law is met with an apparently paradoxical relationship between the lengths and diameters of the vessels. Based on the analysis of CT 3D scans, we show that in the left coronary artery the diameters and lengths of vessels are inversely proportional which explains the applicability of the Finet’s law. We justify theoretically the value of coefficient defining Finet’s law.

Point-Cloud Method for Automated 3D Coronary Tree Reconstruction From Multiple Non-Simultaneous Angiographic Projections.

X-ray angiography is the most commonly used imaging modality for the detection of coronary stenoses due to its high spatial and temporal resolution of lumen contour and its utility to guide coronary interventions in real time. However, the high inter- and intra-observer variability in interpreting the geometry of 3D vascular structure based on multiple 2D image projections is a limitation in the accurate determination of lesion severity. This could be addressed by the 3D reconstruction of the coronary arterial (CA) tree. The automated reconstruction of 3D CA tree from 2D projections is challenging due to the existence of several imaging artifacts, such as vessel overlap, foreshortening, and most importantly respiratory and cardiac motion. Along with these artifacts, the acquisition geometry introduces the possibility of generating false vessel segments in the reconstruction. Our approach aims to reduce the motion artifacts in angiographic projections by developing a new method for rigid and non-rigid motion correction. A novel point-cloud based approach is subsequently introduced for reconstruction of 3D vessel centerlines by iteratively minimizing the reconstruction error. The performance of the proposed 3D reconstruction is evaluated using angiographic projections from 45 patients, producing average reprojection errors of 0.092 ±0.055 mm and 0.910 ±0.352 mm for 3D centerlines reconstruction, when co-registered with the parent vessels on projection planes that were/were not used to derive the 3D reconstruction, respectively. A comparison of the reconstructed 3D lumen surface with optical coherence tomography (OCT) measurements has been performed, showing no statistically significant difference in the luminal cross-sections reconstructed with our method, compared to OCT.

P868Temporal remodeling of coronary arteries during progression of atherosclerosis with serial coronary CT angiography using 3D metrics: results from the PARADIGM study

Abstract Aim To determine compensatory enlargement and luminal reduction of coronary arteries during the progression of atherosclerosis with serial coronary computed tomography angiography (CCTA) by using volumetric measurements. To date, the impact of coronary plaque progression on temporal remodeling, as opposed to the static remodeling, has only been studied with invasive imaging modalities and primarily two-dimensional areas rather than three-dimensional volumes. Methods In total, 1,245 patients with suspected coronary artery disease (CAD) at 13 sites (61±9 years, 39% women) underwent serial CCTA with interscan interval of ≥2 years. The primary objective was to assess volumetric temporal remodeling, defined as the linear association between the change in coronary plaque, lumen and vessel volume at follow-up CCTA on a per-segment level. Temporal remodeling was determined in strata of low and high baseline plaque burden as well as different coronary segments at baseline. Linear regression analysis and Pearson's correlation coefficients were calculated to assess associations. Results Amongst 1,245 patients with 19,920 segments, the median interscan interval was 3.3 (IQR 2.6–4.8) years. For each 1 mm3 increase in plaque volume, the increase in vessel volume was 0.72 mm3 and the decrease in lumen volume was 0.28 mm3 (Figure 1, both p<0.001). Volumetric temporal remodeling was similar in low versus high PAV [0.70 mm3 vs 0.73 mm3 (p for interaction=0.491)] and left-main arteries versus all other segments [0.78 mm3 vs. 0.72 mm3 (p for interaction=0.336)], but not in proximal versus distal segments at baseline [0.75 mm3 vs. 0.61 mm3 (p for interaction=0.020)]. Figure 1. Volumetric temporal remodeling Conclusion In general, coronary plaque grows approximately 70% outward and 30% into the coronary lumen during the progression of atherosclerosis. Volumetric temporal remodeling is not limited by baseline plaque burden, but is potentially dependent on its location within the coronary artery tree. Acknowledgement/Funding NRF of Korea (Grant No. 2012027176); Dalio Institute of Cardiovascular Imaging and Michael J. Wolk Foundation

P1529Coronary and aortic atheroma are not identical diseases: A calcium score comparative study in 1010 patients with a normal SPECT

Abstract Calcium scores of the coronary arteries (CCS) and – more recently – of the the thoracic aorta (TCS), have been established as risk markers for cardiovascular events. Yet, little is known about the relationship between these two calcium scores. In this study, CCS and TCS were compared in 1010 patients with a normal SPECT. Mean age was 64.5±8.7 yrs with 73.4% of men. CCS and TCS ranged between 0 and 5827 for CCS and from 0 to 58600 for TCS, with means of 281.1 and 1206 respectively. Such a difference was expected since the vascular surface of the thoracic aorta is approximately 5 times larger than that of the coronary arterial tree. Both CCS and TCS increased with the number of risk factors (p=0.000841 and p=0.000579) No significant relation was found between CCS and TCS for the entire group. However, when adopting a best-fitting curve model, 2 populations could be clearly identified: those with predominant TCS (N=552), and those with a- relatively- predominant CCS – (N=458). In each of these two groups, CCS and TCS were significantly related (r=0.63 and 0.69 respectively p<2.2e-12). Both groups had a comparable exposition to smoking and diabetes, but Group1 patients had more dyslipemia and high blood pressure than group 2 patients. Conclusion Calcified atheroma was frequently observed In patients with a normal SPECT, but no significant relation existed between CCS and TCS; patients with a predominant atheroma of the coronary arteries were not the same than patients with a predominant atheroma of the aorta, with both groups having different expositions to risk factors. This suggests that atheroma of the coronary arteries and of the thoracic aorta are close but not identical diseases.

P2716Correlation between computed tomography derived ischemia index and conventional fractional flow reserve

Abstract Background Computed tomography (CT) derived ischemia index is a novel tool to determine the significance of coronary artery disease, however, its ability to identify myocardial ischemia has not been examined. Methods From Jan. 2013 to Dec. 2015, 14,000 patients underwent ECG-gated CT coronary angiography for suspected coronary artery disease. From Jan. 2013 to Jan. 2016, 483 patients (589 vessels) underwent conventional FFR to assess myocardial ischemia. Among those, FFR was assessed in 148 patients (167 vessels) within 30 days after CT coronary angiography. We further excluded 24 patients with prior stenting or bypass grafting, 3 patients with multiple MDCT or FFR, and 6 patients with insufficient datasets. Finally, we included 117 patients (127 vessels) to assess the correlation between CT derived ischemia index and conventional FFR. CT derived ischemia index was calculated as follows: left ventricular volume distally to the coronary artery lumen (cm3)/coronary artery lumen area (mm2). Left ventricular volume was automatically determined using Advantage Workstation and divided according to the nearest coronary artery tree. Center of coronary arteries were manually traced and contours of coronary artery lumen were automatically depicted. CT derived ischemia index was calculated at approximately every 0.625mm point of coronary artery. Moving median of consecutive 5 points (approximately 3.125mm) were used to remove outliers. Maximum value of CT derived ischemia index per coronary artery segment was calculated to determine the significance of coronary artery disease. Results Mean age was 71.3±10.5 years and 63.8% of patients were male. Coronary angiography was performed to assess conventional FFR at the median of 13 days (IQR 7 to 18 days) after CT. Majority of the target vessel was left anterior descending artery (71.7%), followed by right coronary artery (14.2%), left circumflex artery (13.4%) and left main coronary artery (0.8%). According to the quantitative coronary angiography, minimum lumen diameter was 1.47±0.32mm with percent diameter stenosis of 48.3±10.4%. Median FFR value was 0.83 (IQR 0.76 to 0.88) and positive test for myocardial ischemia (FFR <0.80) was observed in 42 vessels (33.1%). Maximum CT derived ischemia index per segment ranged from 1.825 to 57.296 (median 8.333, IQR 4.911 to 14.484). There was a negative correlation between CT derived ischemia index and FFR (r=−0.319, 95% confidence interval −0.467 to −0.153, P<0.001). Receiver operating characteristic analysis indicated CT derived ischemia index of 9.962 has 76.2% sensitivity and 70.6% specificity for the presence of FFR<0.80 (AUC 0.73, 95% CI 0.64 to 0.82). Conclusions A novel tool of CT derived ischemia index has a significant negative correlation with conventional FFR in lesions with mild to moderate stenosis. Larger multicenter prospective studies are needed to fully determine the impact of CT derived ischemia index.

Type 2 diabetes mellitus is associated with increased left ventricular mass independent of coronary artery volume

To determine the relationship of left ventricular mass (LVM) and coronary artery volume in diabetic patients and the controls. This work included 448 consecutive patients (206 patients with diabetes and 242 non-diabetic participants) who underwent coronary computed tomography angiography (CTA) for evaluation of coronary artery disease (CAD). The whole coronary artery tree and the LVM were analysed using a cardiac imaging workstation. Multivariable logistic regression analysis was used to determine the independent association with coronary artery lumen volume to LVM ratio (V/M). The total coronary artery cumulative volume and the coronary cumulative length showed no differences between groups (p>0.05); however, the LVM in patients with diabetes was significantly greater than that in controls (132.46±45.04 versus 115.82±29.13, p=0.006), and the total epicardial coronary arterial lumen volume to LVM ratio (V/M) was significantly lower in the diabetic group than in the non-diabetic group (2.02 cm3/100±0.73 g versus 2.31 cm3/100±0.82 g, p=0.024). In multivariate logistic regression analysis, diabetes was associated with V/M (odds ratio [OR] 2.027, 95% confidence interval [CI]: 1.462-2.728, p=0.001), and hypertension was not associated with V/M (OR 1.191, 95% CI: 0.978-1.451, p=0.081). Patients with diabetes demonstrated a significantly lower coronary CTA-derived coronary V/M than controls. V/M may have an important role as a global measure of coronary vasculature in diabetic patients.

Stenosis Detection Algorithm for Coronary Angiograms

Automatic detection of blocks in the angiographic images is a challenging task. The features such as contrast and gradient of the vessels and the background image are playing a vital role in the detection of the blocks in the X-Ray angiograms. Nowadays, doctors manually identify blocks in the coronary vessels. The automation tool is necessary to identify the blocks in the blood vessels of the heart to help the doctors in the diagnosing process. Spatiotemporal nature of the angiography sequences is used to isolate the coronary artery tree. The coronary artery segment is tracked and in each image frame by frame and the arterial width surface is detected. The stenosis identification is done by using coronary vessel surface’s persistent minima and blob analysis. The proposed method is experimented on 42 patients’ dataset. The performance of the proposed method was evaluated by comparing the blocks identified by the algorithm with the hand-labelled ground truth images given by the experts. The proposed method provides an accuracy of 95.5% on 42 patients with a total of 60 image runs.

A One-Dimensional Hemodynamic Model of the Coronary Arterial Tree.

One-dimensional (1D) hemodynamic models of arteries have increasingly been applied to coronary circulation. In this study, we have adopted flow and pressure profiles in Olufsen's 1D structured tree as coronary boundary conditions, with terminals coupled to the dynamic pressure feedback resulting from the intra-myocardial stress because of ventricular contraction. We model a trifurcation structure of the example coronary tree as two adjacent bifurcations. The estimated results of blood pressure and flow rate from our simulation agree well with the clinical measurements and published data. Furthermore, the 1D model enables us to use wave intensity analysis to simulate blood flow in the developed coronary model. Six characteristic waves are observed in both left and right coronary flows, though the waves' magnitudes differ from each other. We study the effects of arterial wall stiffness on coronary blood flow in the left circumflex artery (LCX). Different diseased cases indicate that distinct pathological reactions of the cardiovascular system can be better distinguished through Wave Intensity analysis, which shows agreement with clinical observations. Finally, the feedback pressure in terminal vessels and measurement deviation are also investigated by changing parameters in the LCX. We find that larger feedback pressure increases the backward wave and decreases the forward one. Although simplified, this 1D model provides new insight into coronary hemodynamics in healthy and diseased conditions. We believe that this approach offers reference resources for studies on coronary circulation disease diagnosis, treatment and simulation.

Structural coronary artery remodelling in the rabbit fetus as a result of intrauterine growth restriction

Intrauterine growth restriction (IUGR) is a fetal condition that affects up to 10% of all pregnancies and is associated with cardiovascular structural and functional remodelling that persists postnatally. Some studies have reported an increase in myocardial coronary blood flow in severe IUGR fetuses which has been directly associated to the dilatation of the coronary arteries. However, a direct measurement of the coronaries’ lumen diameter in IUGR has not been reported before. The aim of this paper is to perform, for the first time, a quantitative analysis of the effects of IUGR in cardiac geometry and coronary vessel size in a well-known rabbit model of IUGR using synchrotron-based X-ray Phase Contrast Tomography Imaging (X-PCI). Eight rabbit fetal hearts were imaged non-destructively with X-PCI. 3D reconstructions of the coronary arterial tree were obtained after semi-automatic image segmentation. Different morphometric features including vessel lumen diameter of the three main coronaries were automatically quantified. IUGR fetuses had more globular hearts and dilated coronary arteries as compared to controls. We have quantitatively shown that IUGR leads to structural coronary vascular tree remodelling and enlargement as an adaptation mechanism in response to an adverse environment of restricted oxygen and nutrients and increased perfusion pressure.

The importance of side branches in modeling 3D hemodynamics from angiograms for patients with coronary artery disease

Genesis of atherosclerotic lesions in the human arterial system is critically influenced by the fluid mechanics. Applying computational fluid dynamic tools based on accurate coronary physiology derived from conventional biplane angiogram data may be useful in guiding percutaneous coronary interventions. The primary objective of this study is to build and validate a computational framework for accurate personalized 3-dimensional hemodynamic simulation across the complete coronary arterial tree and demonstrate the influence of side branches on coronary hemodynamics by comparing shear stress between coronary models with and without these included. The proposed novel computational framework based on biplane angiography enables significant arterial circulation analysis. This study shows that models that take into account flow through all side branches are required for precise computation of shear stress and pressure gradient whereas models that have only a subset of side branches are inadequate for biomechanical studies as they may overestimate volumetric outflow and shear stress. This study extends the ongoing computational efforts and demonstrates that models based on accurate coronary physiology can improve overall fidelity of biomechanical studies to compute hemodynamic risk-factors.

Coronary Computed Tomography Angiography as a Gatekeeper to Coronary Revascularization: Emphasizing Atherosclerosis Findings Beyond Stenosis.

Coronary computed tomography angiography (CCTA) is the optimal non-invasive test to rule out coronary artery disease (CAD). Decisions to perform coronary revascularization have traditionally been based upon ischemia testing. This review summarizes the latest observations and trials evaluating the suitability of CCTA to select patients for invasive coronary angiography (ICA) and subsequent revascularization. Recent data shows that beyond stenosis, whole-heart quantification and characterization of coronary atherosclerotic plaque improves the estimation of myocardial ischemia. This comprehensive evaluation of the coronary artery tree has greater diagnostic accuracy for invasive fractional flow reserve (FFR) than conventional stress tests. Further, clinical trials have demonstrated that the performance of CCTA in patients with a clinical indication for ICA results in more effective patient care and significantly lower costs. Besides the excellent ability to rule out CAD, recent data shows that quantification and characterization of the coronary artery tree results in high accuracy for ischemia and that CCTA-guided care to select patients for ICA and revascularization is effective. Trials evaluating revascularization based on CCTA findings may be needed.

Evaluation of fractional flow reserve in patients with stable angina: can CT compete with angiography?

We aimed to compare the performance of FFRCT and FFRQCA in assessing the functional significance of coronary artery stenosis in patients suffering from coronary artery disease with stable angina. A total of 101 stable coronary heart disease (CAD) patients with 181 lesions were recruited. FFRCT and FFRQCA were compared using invasive fractional flow reserve (FFR) as a reference standard. Comparisons between FFRCT and FFRQCA were conducted based on strategies of the geometric reconstruction, boundary conditions, and geometric characteristics. The performance of FFRCT and FFRQCA in detecting hemodynamic significance was also investigated. The performance of FFRCT and FFRQCA in discriminating hemodynamically significant lesions was compared. Good correlation and agreement with invasive FFR was found using FFRCT and FFRQCA (r = 0.809, p < 0.001 and r = 0.755, p < 0.001). A significant difference was observed in the complex coronary artery tree, in which relatively better prediction was observed using FFRCT than FFRQCA when analyzing the stenosis distributed in the middle segment of a stenotic branch (p = 0.036). Moreover, FFRCT was found to be better at predicting hemodynamically insignificant stenosis than FFRQCA (p = 0.007), while the performance of the two parameters was similar in discriminating functional significant lesions using an FFR threshold of ≤ 0.8 as a reference standard. FFRCT and FFRQCA could both accurately rule out functional insignificant lesions in stable CAD patients. FFRCT was found to be better for the noninvasive screening of CAD patients with stable angina than FFRQCA. • FFR CT and FFR QCA were both in good correlation and agreement with invasive FFR measurements. • FFR CT is superior in accuracy and consistency compared to FFR QCA in patients with stenoses distributed in left coronary artery. • The noninvasive nature of FFR CT could provide potential benefit for stable CAD patients on disease management.

Numerical Simulation of Instantaneous Wave-Free Ratio of Stenosed Coronary Artery

Instantaneous wave-free ratio (iFR), an invasive index of coronary artery tree, can evaluate the functional performance of vascular stenosis without pharmacological vasodilators. The noninvasive assessment of diameter stenosis (DS) obtained from coronary computed tomography angiography (CTA) has high false positive rate in contrast to iFR. The aim of this study was to develop a numerical simulation method that predicts the iFR and noninvasively assess the myocardial ischemia. Based on the CTA images, a patient-specific three-dimensional model of the aorta and coronary arteries were reconstructed. A stenosis was created in the left anterior descending artery (LAD) by reducing the DS of geometric model (40%, 50%, 60%, 75% and 90%). The patient-specific LPM boundary condition were set up to compute iFRct value during the wave-free period at the resting condition. The computed pressure and flow of coronary artery were realistic as compared to literature data. In contrast to invasive iFR, the iFRct can make a cost-benefit balance in terms of clinical cost and patient’s health.

Morphometry and hemodynamics of coronary artery aneurysms caused by atherosclerosis

Background and aimsAtherosclerosis is the first etiology of coronary artery aneurysm (CAA). It is, however, challenging to inhibit the development of CAA. The aim of the study is to carry out morphometric and hemodynamic analyses in epicardial coronary arteries of patients with CAAs caused by atherosclerosis. MethodsVarious morphometric parameters were obtained from the reconstructed epicardial coronary arterial trees of 61 patients and multiple hemodynamic parameters were determined from the computed flow fields. A two-step analysis method was proposed to enhance the risk assessment of CAAs, i.e., coronary artery bifurcation is the major risk factor for CAA followed by high aneurysm shape index (L/W, where L and W refer to the aneurysm length and maximum diameter, respectively). ResultsPatients with CAA covering a bifurcation have the higher occurrence (71% and 55% for L/W ≥ 2 and L/W < 2, respectively) of myocardial ischemia relevant to abnormal hemodynamic parameters in comparison with those with CAA in one vessel (43% and 40% for L/W ≥ 2 and L/W < 2, respectively). Patients with CAA of L/W ≥ 2 covering a bifurcation show the worst hemodynamic environment. ConclusionsMorphometric and hemodynamic studies support the two-step analysis method, which provides a clinical rationale for the noninvasive assessment of CAAs.

A model-guided method for improving coronary artery tree extractions from CCTA images

PurposeAutomatically extracted coronary artery trees (CATs) from coronary computed tomography angiography images could contain incorrect extractions which require manual corrections before they can be used in clinical practice. A model-guided method for improving the extracted CAT is described to automatically detect potential incorrect extractions and improve them.MethodsThe proposed method is a coarse-to-fine approach. A coarse improvement is first applied on all vessels in the extracted CAT, and then a fine improvement is applied only on vessels with higher clinical significance. Based upon a decision tree, the proposed method automatically and iteratively performs improvement operations for the entire extracted CAT until it meets the stop criteria. The improvement in the extraction quality obtained by the proposed method is measured using a scoring system. 18 datasets were used to determine optimal values for the parameters involved in the model-guided method and 122 datasets were used for evaluation.ResultsCompared to the initial automatic extractions, the proposed method improves the CATs for 122 datasets from an average quality score of 87 ± 6 to 93 ± 4. The developed method is able to run within 2 min on a typical workstation. The difference in extraction quality after automatic improvement is negatively correlated with the initial extraction quality (R = − 0.694, P < 0.001).ConclusionWithout deteriorating the initially extracted CATs, the presented method automatically detects incorrect extractions and improves the CATs to an average quality score of 93 guided by anatomical statistical models.

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 ± 0.1s and fully automatic coronary tree extraction required around 20s. 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.

MULTIVESSEL CORONARY ARTERY ANEURYSMS PRESENTING AS MYOCARDIAL ISCHEMIA

SESSION TITLE: Cardiovascular Disease SESSION TYPE: Med Student/Res Case Report PRESENTED ON: 10/09/2018 07:30 AM - 08:30 AM INTRODUCTION: Aneurysmal disease of the coronary artery tree (CAA) is a rare condition with an incidence of 0.3-4.9% of patients undergoing coronary angiography. The majority of cases occur in the proximal segments of the epicardial arteries and typically involve only one artery [1]. Involvement of three coronary vessels or the left main coronary artery is particularly rare, found in only 3.5% of CAA patients [2]. Multi-vessel CAA can present as an ischemic coronary syndrome, and can be challenging to manage. CASE PRESENTATION: A 48 year old African American non-smoking female with history of Parry Romberg syndrome, hypertension, obesity, and chronic kidney disease presented with progressive, intermittent, non-exertional chest pain. EKG showed voltage criteria for left ventricular hypertrophy (LVH). Bedside echocardiogram showed moderate LVH and akinesis of the basal inferior myocardial segment. Initial troponin I was 0.7ng/mL, and rose to peak of 6.16ng/mL. She was given aspirin, clopidogrel, and intravenous heparin drip. Coronary angiography showed aneurysmal disease of the left main, left anterior descending, left circumflex, and right coronary arteries, without evidence of thrombus angiographically. There were diffuse mild luminal irregularities, and a discrete 90% stenosis of the proximal right posterior descending artery. Percutaneous intervention was not performed. The patient denied history of Kawasaki’s disease. Subsequent vascular evaluation included an MR angiogram of the head, chest, abdomen and pelvis which were negative. Antinuclear antibodies, rheumatoid factor, and antineutrophil cytoplasmic antibodies were all negative. C-reactive protein and erythrocyte sedimentation rate were mildly elevated (1.01mg/dL and 32mm/Hr respectively). Her lipid profile demonstrated LDL 114mg/dL. She was discharged with dual antiplatelet therapy and high intensity statin. At 3 month follow up, she reported occasional palpitations with no chest pain, and at one year follow up she reported no symptoms. DISCUSSION: CAA is typically atherosclerotic in origin, as in our patient, although other causes exist. Previously it was believed that atherosclerosis caused CAA by increased pressure and shear stress due to luminal narrowing; however, it is now postulated that it may be due to generalized endovascular inflammation [2]. There is no known association between Parry Romberg syndrome and atherosclerosis or CAA. Medical management of CAA is limited to anticoagulant, antiplatelet, and anti-atherosclerotic therapy. Consensus Indications for percutaneous or surgical interventions are limited given the rarity of the disease; however, they are typically reserved for symptomatic flow limiting disease or if there is high risk of rupture. CONCLUSIONS: CAA is a rare condition that may mimic myocardial ischemia on presentation. Treatment options for multi-vessel CAA are limited given the paucity of data on the disease. Reference #1: 1. Abou Sherif, S. et al. “Coronary Artery Aneurysms: A Review of the Epidemiology, Pathophysiology, Diagnosis, and Treatment.” Frontiers in Cardiovascular Medicine 4 (2017): 24. PMC. 17 Feb. 2018. Reference #2: 2. Mata, Karina M. et al. “Coronary Artery Aneurysms: An Update.” Novel Strategies in Ischemic Heart Disease, 2017. Dr.Umashankar Lakshmanadoss (Ed.) DISCLOSURES: No relevant relationships by Michael Berlowitz, source=Web Response No relevant relationships by Andrew Mehlman, source=Web Response

Coronary Artery Centerline Tracking and Coronary Artery Tree Segmenting in X-ray Angiographic Images

Coronary Artery Centerline Tracking and Coronary Artery Tree Segmenting in X-ray Angiographic Images