Left Coronary Tree Research Articles

A new understanding of coronary curvature and haemodynamic impact on the course of plaque onset and progression

The strong link between atherosclerosis and luminal biomechanical stresses is well established. Yet, this understanding has not translated into preventative coronary diagnostic imaging, particularly due to the under-explored role of coronary anatomy and haemodynamics in plaque onset, which we aim to address with this work. The left coronary trees of 20 non-stenosed (%diameter stenosis [%DS] = 0), 12 moderately (0 < %DS < 70) and 7 severely (%DS ≥ 70) stenosed cases were dissected into bifurcating and non-bifurcating segments for whole-tree and segment-specific comparisons, correlating nine three-dimensional coronary anatomical features, topological shear variation index (TSVI) and luminal areas subject to low time-average endothelial shear stress (%LowTAESS), high oscillatory shear index (%HighOSI) and high relative residence time (%HighRRT). We found that TSVI is the only metric consistently differing between non-stenosed and stenosed cases across the whole tree, bifurcating and non-bifurcating segments ( p < 0.002, AUC = 0.876), whereas average curvature and %HighOSI differed only for the whole trees ( p < 0.024) and non-bifurcating segments ( p < 0.027), with AUC > 0.711. Coronary trees with moderate or severe stenoses differed only in %LowTAESS ( p = 0.009) and %HighRRT ( p = 0.012). This suggests TSVI, curvature and %HighOSI are potential factors driving plaque onset, with greater predictive performance than the previously recognized %LowTAESS and %HighRRT, which appears to play a role in plaque progression.

Virtual FFR Quantified with a Generalized Flow Model Using Windkessel Boundary Conditions

Fractional flow reserve (FFR) has proved its efficiency in improving patient diagnosis. In this paper, we consider a 2D reconstructed left coronary tree with two artificial lesions of different degrees. We use a generalized fluid model with a Carreau law and use a coupled multidomain method to implement Windkessel boundary conditions at the outlets. We introduce our methodology to quantify the virtual FFR and conduct several numerical experiments. We compare FFR results from the Navier–Stokes model versus generalized flow model and for Windkessel versus traction-free outlet boundary conditions or mixed outlet boundary conditions. We also investigate some sources of uncertainty that the FFR index might encounter during the invasive procedure, in particular, the arbitrary position of the distal sensor. The computational FFR results show that the degree of stenosis is not enough to classify a lesion, while there is a good agreement between the Navier–Stokes model and the non-Newtonian flow model adopted in classifying coronary lesions. Furthermore, we highlight that the lack of standardization while making FFR measurement might be misleading regarding the significance of stenosis.

Topologic and Hemodynamic Characteristics of the Human Coronary Arterial Circulation.

BackgroundMany processes contributing to the functional and structural regulation of the coronary circulation have been identified. A proper understanding of the complex interplay of these processes requires a quantitative systems approach that includes the complexity of the coronary network. The purpose of this study was to provide a detailed quantification of the branching characteristics and local hemodynamics of the human coronary circulation.MethodsThe coronary arteries of a human heart were filled post-mortem with fluorescent replica material. The frozen heart was alternately cut and block-face imaged using a high-resolution imaging cryomicrotome. From the resulting 3D reconstruction of the left coronary circulation, topological (node and loop characteristics), topographic (diameters and length of segments), and geometric (position) properties were analyzed, along with predictions of local hemodynamics (pressure and flow).ResultsThe reconstructed left coronary tree consisted of 202,184 segments with diameters ranging from 30 μm to 4 mm. Most segments were between 100 μm and 1 mm long. The median segment length was similar for diameters ranging between 75 and 200 μm. 91% of the nodes were bifurcations. These bifurcations were more symmetric and less variable in smaller vessels. Most of the pressure drop occurred in vessels between 200 μm and 1 mm in diameter. Downstream conductance variability affected neither local pressure nor median local flow and added limited extra variation of local flow. The left coronary circulation perfused 358 cm3 of myocardium. Median perfused volume at a truncation level of 100 to 200 μm was 20 mm3 with a median perfusion of 5.6 ml/min/g and a high local heterogeneity.ConclusionThis study provides the branching characteristics and hemodynamic analysis of the left coronary arterial circulation of a human heart. The resulting model can be deployed for further hemodynamic studies at the whole organ and local level.

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.

Tender Endothelium Syndrome: Combination of Hypotension, Bradycardia, Contrast Induced Chest Pain, and Microvascular Angina.

Hypotension, bradycardia, and contrast induced chest pain are potential complications of cardiac catheterization and coronary angiography. Catheter-induced coronary spasm has been occasionally demonstrated, but its relationship to spontaneous coronary spasm is unclear. We describe a 64-year-old female who underwent coronary artery bypass surgery in 1998 on the basis of an angiographic diagnosis of severe left main disease, who recently presented with increasingly frequent typical angina. Repeat coronary angiography was immediately complicated by severe chest pain, hypotension, and bradycardia but demonstrated only mild disease of the left main artery and entire coronary tree with complete occlusion of her prior grafts. This reaction was almost identical to that observed during her original coronary angiogram. We now believe her original angiogram was complicated by severe catheter-induced left main spasm, with the accompanying contrast reaction attributed to left main disease, and the occlusion of coronary grafts explained by the absence of significant left main disease. The combination of these symptoms has not been documented in the literature. In this instance, these manifestations erroneously led to coronary bypass surgery. It is unknown whether routine, systematic injection of intracoronary nitroglycerin prior to angiography might blunt the severity of such reactions.

Abstract 15816: Normal Distribution of Wall Shear Stress in the Coronary Arteries

Introduction: The ability to detect hemodynamically significant coronary artery disease non-invasively has been a goal that has the potential to improve patient care significantly. New non-invasive approaches using coronary CT angiograms (CCTAs) have been proposed and appear to show some promise. Hypothesis: One such method is the measurement of measuring wall shear stress (WSS), the tangential force of flowing blood against the artery wall, using computational fluid dynamics (CFD). However, in order to deem this technique useful in clinical practice, the normal values must first be defined. These values have been minimally reported and are limited to the left coronary tree. Methods: We ran a CFD simulation of WSS on 3-D reconstructions of the coronary arteries derived from the CCTAs of 35 patients with either no disease or non-obstructive (< 50%) stenosis from the DeFACTO trial, a multi-center study. The resulting model was segmented according to the Society of Cardiovascular CT guidelines, separating the proximal and distal parts of each artery as well as the major side branches. The segments were composed of WSS values at hundreds of points along the vessel wall. The median value was taken as a representative of each segment. Results: The average values were calculated and varied significantly from one another, especially the proximal and distal parts of the same artery, as showing in Figure 1. Conclusions: These results establish the first known WSS distribution within all of the coronary arteries and serve as a foundation for defining a cut-off for abnormal values. Importantly, they also illuminate the variability of WSS that occurs even throughout a single artery and suggests that perhaps multiple abnormal cutoffs need to be established to evaluate WSS based on the location of the stenosis.

Left anterior descending coronary artery fistula to left ventricle: The revenge of a well treated myocardial infarction in the era of primary percutaneous angioplasty

To better discriminate between different diagnoses, once patient's informed consent was obtained, we performed coronary angiography which demonstrated the absence of vessel stenosis but the presence of opacification of the left ventricular cavity almost simultaneously with the left coronary tree (Fig. 2B): we identified a multi-vessel like structure originating from the left anterior descending artery (LAD) functioning like a conduit between it and the left ventricular cavity. Comparing this angiography with the previous one made during the acute myocardial infarction seven years before, this structure was not visible (Fig. 2A). Suspecting a new formation not visible with echo, we performed magnetic resonance and computed tomography (Fig. 3 )t o better explore the surface of the heart and the thickness of the myocardial muscle, but no more information was obtained, Therefore we concluded for an acquired coronary artery fistula (CAF) after myocardial infarction. Coronary artery fistula is a rare and usually congenital anomaly (0.05–0.25%of patientswhoundergo coronaryangiographyfor anyrea

Left Main Coronary Artery Atresia in an Asymptomatic Elderly Adult

Coronary artery anomalies are uncommon, with an incidence ranging between 0.2% and 1.4%. Among those least frequently observed is left main coronary artery atresia. We report the case of a 72-year-old man, with asymptomatic severe aortic stenosis and moderate ventricular dysfunction. He underwent preoperative coronary angiography in which it was not possible to examine the left main coronary artery. Right coronary artery was dominant and the conal branch had an independent origin (Figure A and video 1 of the supplementary material). Blood was delivered to the left coronary tree by way of collateral circulation arising from the conal branch, which was anastomosed to the segment proximal to the anterior descending artery (Figures B and C, asterisks; video 2 of the supplementary material). The anterior descending and circumflex arteries were connected at their origin in the base of a blind pouch (Figure B, arrow head). There was no evidence of significant coronary artery calcification or stenosis. High-resolution computed tomography was carried out to ensure complete evaluation of the anatomy. Three-dimensional reconstruction revealed left main coronary artery atresia and absence of the left coronary ostium in the left sinus of Valsalva (Figure D, arrow head), and confirmed the normal position of the anterior descending and circumflex arteries. The double-barreled origin of the right coronary artery and the conal branch and their anastomosis to the anterior descending artery were also clearly visualized (Figures E; Figure D, asterisk). Left main coronary artery atresia was confirmed during valve replacement surgery and, 1 year later, the patient remained asymptomatic and with normal ventricular function.

Comparison of a Safety Strategy Using Transradial Access and Dual‐Axis Rotational Coronary Angiography with Transfemoral Access and Standard Coronary Angiography

We sought to investigate the radiation exposure and contrast utilization associated with using a strategy of transradial access and rotational angiography (radial-DARCA) compared to the traditional approach of transfemoral access and standard angiography (femoral-SA). There is an increased focus on optimizing patient safety during cardiac catheterization procedures. Professional guidelines have highlighted physician responsibility to minimize radiation doses and contrast volume. Dual axis rotational coronary angiography (DARCA) is the most recently investigated type of rotational angiography. This new technique permits complete visualization of the left or right coronary tree with a single injection, and is felt to reduce contrast and radiation exposure. A total of 56 consecutive patients who underwent radial-DARCA were identified. From the same time period, an age- and gender-matched group of 61 patients who had femoral-SA were selected for comparison. Total volume of contrast agent used, fluoroscopy time, and 2 measures of radiation dose (dose area product and air kerma) were recorded for each group. Mean contrast agent use and patient radiation exposure of the radial-DARCA group were significantly less than that of the femoral-SA group. There was no significant difference in fluoroscopy time between the 2 groups. Physicians can successfully employ an innovative safety strategy of transradial access combined with DARCA that is feasible and is associated with lower radiation doses and contrast volume than femoral artery access and traditional coronary angiography approach.

Benefits of dual-axis rotational coronary angiography in routine clinical practice

Dual-axis rotational coronary angiography (DARCA) is a new imaging technique involving three-dimensional rotation of the gantry around the patient with simultaneous left to right and craniocaudal movements. This allows complete imaging of the left or right coronary tree with a single acquisition run. Previous small studies have indicated that DARCA is associated with reduced radiation dose and contrast use in comparison with standard coronary angiography (SCA). We conducted a registry of unselected patients undergoing DARCA or SCA. DARCA was used in 107 patients and SCA in 105 patients. Mean number of acquisition runs was 2.6 for DARCA and 6.9 for SCA (P < 0.0001). Mean radiation dose (dose-area product, DAP) was 30.4 Gy cm(2) for SCA and 15.9 Gy cm(2) for DARCA (P < 0.0001). Mean contrast volume was 41.7 ml for SCA and 25.7 ml for DARCA (P < 0.0001). Case time for DARCA in the first half of the study was 20.8 ± 1.4 min compared with 15.2 ± 2.0 min in the second half of the study (P = 0.0015), suggesting a learning curve. In the DARCA group, 64 % of patients required only two acquisition runs for complete and satisfactory imaging. There were no adverse effects resulting from DARCA. Two cases are presented to illustrate the diagnostic ability of DARCA. DARCA was associated with a 48 % reduction in radiation dose and 36 % reduction in contrast volume in comparison with SCA, with comparable diagnostic ability.

Intraspecific scaling laws of vascular trees

A fundamental physics-based derivation of intraspecific scaling laws of vascular trees has not been previously realized. Here, we provide such a theoretical derivation for the volume-diameter and flow-length scaling laws of intraspecific vascular trees. In conjunction with the minimum energy hypothesis, this formulation also results in diameter-length, flow-diameter and flow-volume scaling laws. The intraspecific scaling predicts the volume-diameter power relation with a theoretical exponent of 3, which is validated by the experimental measurements for the three major coronary arterial trees in swine (where a least-squares fit of these measurements has exponents of 2.96, 3 and 2.98 for the left anterior descending artery, left circumflex artery and right coronary artery trees, respectively). This scaling law as well as others agrees very well with the measured morphometric data of vascular trees in various other organs and species. This study is fundamental to the understanding of morphological and haemodynamic features in a biological vascular tree and has implications for vascular disease.

Safety and efficacy of dual‐axis rotational coronary angiography vs. standard coronary angiography

To determine the safety and efficacy of dual-axis rotational coronary angiography (DARCA) by directly comparing it to standard coronary angiography (SA). Standard coronary angiography (SA) requires numerous fixed static images of the coronary tree and has multiple well-documented limitations. Dual-axis rotational coronary angiography (DARCA) is a new rotational acquisition technique that entails simultaneous LAO/RAO and cranial/caudal gantry movement. This technological advancement obtains numerous unique images of the left or right coronary tree with a single coronary injection. We sought to assess the safety and efficacy of DARCA as well as determine DARCA's adequacy for CAD screening and assessment. Thirty patients underwent SA following by DARCA. Contrast volume, radiation dose (DAP) and procedural time were recorded for each method to assess safety. For DARCA acquisitions, blood pressure (BP), heart rate (HR), symptoms and any arrhythmias were recorded. All angiograms were reviewed for CAD screening adequacy by two independent invasive cardiologists. Compared to SA, use of DARCA was associated with a 51% reduction in contrast, 35% less radiation exposure, and 18% shorter procedural time. Both independent reviewers noted DARCA to be at least equivalent to SA with respect to the ability to screen for CAD. DARCA represents a new angiographic technique which is equivalent in terms of image quality and is associated with less contrast use, radiation exposure, and procedural time than SA.

Non-invasive assessment of allometric scaling laws in the human coronary tree

Assessing the geometry of the coronary arteries in a patient can help to better explain coronary artery disease (CAD) development. Allometric scaling functions were successfully applied to describe how essential materials are transported through recursive networks, also observed in the coronary tree. In this work we used skeletonization methods on multislice computed tomography (MSCT) images to render the coronary tree in 3D. Fifty subjects were recruited in two groups: 1) free from plaques and 2) with focal lesions. The left coronary tree was segmented using a custom algorithm with minimum user intervention. Vessels were separated using a stem-crown architecture. Cumulative arterial length ( L) with volume ( V) and vessel stem diameter ( D STEM) with distal L functions were analysed. In the allometric functions L = k v V β and D STEM = k L L γ , no significant differences were found between groups. The scaling exponent range for β was 0.6–0.9 and for γ was 0.1–0.4. Values were not different from other studies in pigs. In a Log–Log scatter plot in all patients, lines were parallel, confirmed with an ANCOVA. In other words, the allometric function stood for all patients. The idea that parameters from diseased hearts are expected to deviate from normal was not revealed in this study. We believe that CAD did not disturb the allometric relations due to the focal nature of the lesions and the absence of diffuse CAD. Further combination of MSCT with 3D morphological extraction algorithms can help to overcome the qualitative analysis of a patient vasculature and advance into new clinical quantitative perspectives.

Patient-specific computational fluid dynamics: structured mesh generation from coronary angiography

Patient-specific simulations are widely used to investigate the local hemodynamics within realistic morphologies. However, pre-processing and mesh generation are time consuming, operator dependent, and the quality of the resulting mesh is often suboptimal. Therefore, a semi-automatic methodology for patient-specific reconstruction and structured meshing of a left coronary tree from biplane angiography is presented. Seven hexahedral grids have been generated with the new method (50,000-3,200,000 cells) and compared to nine unstructured tetrahedral grids with prismatic boundary layer (150,000-3,100,000 cells). Steady-state blood flow simulation using Computational Fluid Dynamics (CFD) has been used to calculate the Wall Shear Stress (WSS). Our results (99 percentile, area-weighted and local WSS values along a line) demonstrate that hexahedral meshes with respect to tetrahedral/prismatic meshes converge better, and for the same accuracy of the result, six times less cells and 14 times less computational time are required. Hexahedral meshes are superior to tetrahedral/prismatic meshes and should be preferred for the calculation of the WSS.

Left Main Coronary Artery Atresia Diagnosed with 128-MDCT

A female with intermittent chest discomfort and an inconclusive exercise treadmill test was submitted for a non-invasive coronary angiography with 128-multidetector computed tomography (MDCT) with prospective triggering (1.7mSv). The coronary arteries were free of atherosclerotic coronary artery disease (CAD). However, MDCT clearly demonstrated a congenital anomaly of the coronary arteries, with absence of the left coronary ostium and left main trunk (black arrow). artery. Subsequent invasive coronary angiography confirmed the MDCT findings. Anomalies of the coronary arteries occur in about 1% of the population. Congenital absence of LM is a rare vascular anomaly, with only a few more than 30 cases reported in the literature. Chest pain, in this type of anomaly, has been described in the absence of CAD and frequently in patients older than thefifthdecade.One explanation is the alteration of the flow angle, compression or kinking of the A dominant right coronary artery (RCA) provided blood supply via conus branch (white arrow) to the left anterior descending (LAD) and left circumflex (Cx) arteries, which were located at their normal position. The conus branch (white arrow) coursed anteriorly to the main pulmonary collateral, which probably occurred in this patient. MDCT can demonstrate the absence of the LM and the presence of collaterals to the left coronary tree aswell as its path and relationship with the great vessels, associated CAD or the existence of intramyocardial paths. In addition, the new scanners provide a rapid diagnosis and effective radiation dose of less than 2mSv.

Complex Coronary Sinus Fistula in a 58-year-old Female

Coronary artery aneurysms and arterio-venous fistulae are uncommon malformations. We report the case of a 58-year-old woman with a large aneurysmal fistula arising from the left coronary tree and involving the entire coronary sinus venous system, resulting in significant left-to-right shunt. We discuss the management of aneurysmal fistulae of the coronary arteries, and the merits of prophylaxis for thrombotic complications of large aneurysms. We recommend consideration of warfarinisation in addition to aspirin of such patients post-operatively.

Ostial left main coronary stenosis in a frequent flyer

A 52 year old gentleman presented with chest pain, after a long distance flight from India; he had made long haul flights every 2 weeks over the last 5 years as part of his job. His ECG revealed T wave inversion in leads V1-3. Cardiac biomarkers including troponin were negative; we proceeded to exercise stress testing (EST). This revealed 2 mm ST depression at 2 min of the standard Bruce protocol, associated with chest pain. He was taken immediately to the coronary catheterization laboratory; engagement of the left main caused pressure damping with 6 French, then 5 French diagnostic Judkins left 4 catheters. An ostial left main stenosis was seen; the right and left coronary trees otherwise had no significant stenoses. He had normal LV function. He underwent inpatient CABG 7 days later.

Displacement and velocity of the coronary arteries: cardiac and respiratory motion

This paper presents measurements of three-dimensional (3-D) displacements and velocities of the coronary arteries due to the myocardial beating motion and due to breathing. Data were acquired by reconstructing the coronary arteries and their motion from biplane angiograms in 10 patients. A parametric motion model was used to separate the cardiac and breathing motion fields. The arteries move consistently toward the left, inferior, and anterior during a cardiac contraction. The displacement and velocity of the right coronary artery during a cardiac contraction was larger than measured for the left coronary tree. Cardiac motion dominates the respiratory motion of the coronary arteries during spontaneous breathing. On inspiration, the arteries move caudally, but the motion in the left-right and anterior-posterior axes was variable. Spatial variation in respiratory displacement and velocity of the coronary arteries indicates that the breathing motion of the heart is more complex than a 3-D translation.

Towards quantitative analysis of coronary CTA

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

Rest period duration of the coronary arteries: Implications for magnetic resonance coronary angiography

Magnetic resonance (MR) and computed tomography coronary imaging is susceptible to artifacts caused by motion of the heart. The presence of rest periods during the cardiac and respiratory cycles suggests that images free of motion artifacts could be acquired. In this paper, we studied the rest period (RP) duration of the coronary arteries during a cardiac contraction and a tidal respiratory cycle. We also studied whether three MR motion correction methods could be used to increase the respiratory RP duration. Free breathing x-ray coronary angiograms were acquired in ten patients. The three-dimensional (3D) structure of the coronary arteries was reconstructed from a biplane acquisition using stereo reconstruction methods. The 3D motion of the arterial model was then recovered using an automatic motion tracking algorithm. The motion field was then decomposed into separate cardiac and respiratory components using a cardiac respiratory parametric model. For the proximal-to-middle segments of the right coronary artery (RCA), a cardiac RP (<1 mm 3D displacement) of 76+/-34 ms was measured at end systole (ES), and 65+/-42 ms in mid-diastole (MD). The cardiac RP was 80+/-25 ms at ES and 112+/-42 ms at MD for the proximal 5 cm of the left coronary tree. At end expiration, the respiratory RP (in percent of the respiratory period) was 26+/-8% for the RCA and 27+/-17% for the left coronary tree. Left coronary respiratory RP (<0.5 mm 3D displacement) increased with translation (32% of the respiratory period), rigid body (51%), and affine (79%) motion correction. The RCA respiratory RP using translational (27%) and rigid body (33%) motion correction were not statistically different from each other. Measurements of the cardiac and respiratory rest periods will improve our understanding of the temporal and spatial resolution constraints for coronary imaging.