Coronary Wall Research Articles

Is size really all that matters? Remarks on size and necrotic core content of atherosclerotic plaques

Is size really all that matters? Remarks on size and necrotic core content of atherosclerotic plaques

Sympathetic dysfunction of systemic right ventricle in congenitally corrected transposition of the great arteries

We evaluate the systemic right ventricle (SRV) failure of congenitally corrected transposition of the great arteries using the scintigraphic studies in a case with 32-year-old male who improved the heart failure by the use of beta-adrenergic blockers. The myocardial perfusion sympathetic nervous system activity mismatch with preserved coronary flow and wall thickness indicates a distinctive feature as SRV cardiomyopathy, suggesting the importance of recovery of SRV sympathetic dysfunction for improving the prognosis.

Acute coronary syndrome due to coronary artery compression by a metastatic cardiac tumor

A 60-year-old female without coronary risk factors was admitted to the hospital with ST-elevation acute coronary syndrome (ACS). She had previously suffered breast cancer and received radical mastectomy followed by chemotherapy and radiation. Emergent coronary angiography showed an occlusion of the proximal left anterior descending coronary artery (LAD) and coronary angioplasty was performed. Coronary computed tomography (CT) angiography (CTA) disclosed a tumor invading the left ventricular anterior wall and surrounding the coronary artery. Myocardial single-photon-emission CT (SPECT) using 123I-BMIPP showed a defect in the same portion. A fusion image of the CTA and the SPECT delineated a tumor surrounding the coronary artery. She finally died two months later from a terminal condition. Autopsy demonstrated a tumor involving the left ventricular anterior wall and surrounding the LAD. Pathology of the affected LAD showed only fibrous plaque without vulnerable plaque, thrombus, or tumor invasion to the coronary wall. Thus, compression of the coronary artery by the metastatic tumor was the most likely mechanism of ACS.

Dynamic geometric contour models for segmenting intravascular ultrasound image series in 3-dimensional surface reconstruction of coronary vessel walls

Dynamic geometric contour models for segmenting intravascular ultrasound image series in 3-dimensional surface reconstruction of coronary vessel walls

The Role of the Framingham Risk Score to Predict the Presence of Subclinical Coronary Atherosclerosis in Patients with HIV Infection

The Role of the Framingham Risk Score to Predict the Presence of Subclinical Coronary Atherosclerosis in Patients with HIV Infection

Prenatal Cocaine Exposure Causes Sex-Dependent Impairment in the Myogenic Reactivity of Coronary Arteries in Adult Offspring

Cocaine abuse is a significant problem among pregnant women. The present study tested the hypothesis that prenatal cocaine exposure impairs myogenic reactivity of coronary arteries in adult offspring. Pregnant rats received cocaine (30 mg kg(-1) day(-1)) or saline from days 15 to 21 of gestational age, and experiments were conducted in 3-month-old offspring. In pressurized coronary septal arteries, the diameter and vessel wall intracellular Ca2+ concentrations were measured simultaneously in the same tissue as a function of intraluminal pressure. Cocaine did not affect KCl-induced contractions of coronary arteries in either males or females but decreased the distensibility in male vessels. In male offspring, cocaine treatment resulted in a significant decrease in pressure-dependent myogenic contractions. Inhibition of eNOS with NG-nitro-L-arginine did not alter the myogenic response in either saline control or cocaine-treated animals. In females, cocaine caused a significant increase in pressure-dependent myogenic contractions. NG-nitro-L-arginine did not affect the myogenic response in the control animals but blocked the cocaine-mediated effect. In both males and females, the pressure-induced increases in vessel wall Ca2+ concentrations were not significantly different between cocaine and saline groups. The ratio of changes in the diameter to Ca2+ concentrations in the pressurized arteries was significantly less in male but greater in female offspring after cocaine treatment. The results suggest that prenatal cocaine exposure causes reprogramming of coronary myogenic tone via changes in the Ca2+ sensitivity in a sex-dependent manner, leading to an increased risk of dysfunction of coronary autoregulation in adult offspring.

Intimal Dissection Causing Late Thrombosis of a Covered Stent

Late thrombosis is a rare but a potentially catastrophic complication of coronary stenting procedures.1 It is recognized to occur in both bare metal and drug-eluting stents2 and seems to occur at a low incidence (≈0.6% per year) for at least 3 years postprocedure.3 Intravascular imaging with optical coherence tomography (OCT) can provide high-resolution images (10 to 20 μm) of the coronary vessel wall and is being increasingly used to provide insight into the risks and mechanisms of late stent thrombosis (ST).4 Covered stents are occasionally used in situations where percutaneous intervention has caused coronary perforation or rupture. We present a case of ST within a covered stent associated with an unusual …

Vascular Cell Adhesion Molecule-1 Expression in Endothelial Cells Exposed to Physiological Coronary Wall Shear Stresses

Atherosclerosis is consistently found in bifurcations and curved segments of the circulatory system, indicating disturbed hemodynamics may participate in disease development. In vivo and in vitro studies have shown that endothelial cells (ECs) alter their gene expression in response to their hemodynamic environment, in a manner that is highly dependent on the exact nature of the applied forces. This research exposes cultured ECs to flow patterns present in the coronary arterial network, in order to determine the role of hemodynamic forces in plaque initiation. Vascular cell adhesion molecule-1 (VCAM-1) was examined as an indicator of plaque growth, as it participates in monocyte adhesion, which is one of the initial steps in the formation of fatty lesions. The hemodynamics of a healthy right and left coronary artery were determined by reconstructing 3D models from cineangiograms and employing computational fluid dynamic models to establish physiological coronary flow patterns. Wall shear stress (WSS) profiles selected from these studies were applied to ECs in a cone and plate bioreactor. The cone and plate system was specifically designed to be capable of reproducing the high frequency harmonics present in physiological waveforms. The shear stresses chosen represent those from regions prone to disease development and healthier arterial segments. The levels of the transcriptional and cell surface anchored VCAM-1 were quantified by flow cytometry and real time RT-PCR over a number of timepoints to obtain a complete picture of the relationship between this adhesion molecule and the applied shear stress. The WSS profiles from regions consistently displaying a higher incidence of plaques in vivo, induced greater levels of VCAM-1, particularly at the earlier timepoints. Conversely, the WSS profile from a straight section of vessel with undisturbed flow indicated no upregulation in VCAM-1 and a significant downregulation after 24 h, when compared with static controls. Low shear stress from the outer wall of a bifurcation induced four times the levels of VCAM-1 messenger ribonucleic acid (mRNA) after four hours when compared with levels of mRNA induced by WSS from a straight arterial section. This shear profile also induced prolonged expression of the surface protein of this molecule. The current study has provided insight into the possible influences of coronary hemodynamics on plaque localization, with VCAM-1 only significantly induced by the WSS from disease prone regions.

Wall thickness of coronary vessels varies transmurally in the LV but not the RV: implications for local stress distribution

Since the right and left ventricles (RV and LV) function under different loading conditions, it is not surprising that they differ in their mechanics (intramyocardial pressure), structure, and metabolism; such differences may also contribute to differences in the coronary vessel wall. Our hypothesis is that intima-media thickness (IMT), IMT-to-radius (IMT-to-R) ratio, and vessel wall stress vary transmurally in the LV, much more than in the RV. Five normal Yorkshire swine were used in this study. The major coronary arteries were cannulated through the aorta and perfusion fixed with 6.25% glutaraldehyde and casted with a catalyzed silicone-elastomer solution. Arterial and venous vessels were obtained from different transmural locations of the RV and LV, processed for histological analysis, and measured with an imaging software. A larger transmural gradient was found for IMT, IMT-to-R ratio, and diastolic circumferential stress in vessels from the LV than the nearly zero transmural slope in the RV. The IMT of arterial vessels in the LV showed a slope of 0.7 +/- 0.5 compared with 0.3 +/- 0.3 of arterial vessels in the RV (P <or= 0.05). The slope for venous vessels in the LV was 0.14 +/- 0.14 vs. 0.06 +/- 0.05 in the RV. The present data reflect the local structure-function relation, where the significant gradient in intramyocardial pressure in the LV is associated with a significant gradient of IMT and IMT-to-R ratio, unlike the RV. This has important implications for local adaptation of transmural loading on the vessel wall and vascular remodeling when the loading is perturbed in cardiac hypertrophy or heart failure.

Prevention of vasa vasorum neovascularization attenuates early neointima formation in experimental hypercholesterolemia

Vasa vasorum (VV) neovascularization is a key feature of early atherosclerosis and adds substantial endothelial exchange-surface to the coronary vessel wall. Thus, it is conceivable that VV neovascularization favors the entry of pro-inflammatory and pro-atherosclerotic blood components into the coronary vessel wall. We sought to investigate the effects of Thalidomide (Th), a potent anti-angiogenic drug on vasa vasorum (VV) neovascularization, vessel wall inflammation, and neointima formation in early experimental atherosclerosis. Female domestic swine, 3 months old, were fed normal (N, n = 12) or high-cholesterol diet (HC, n = 12) for 3 months. In each group six pigs were randomized to 200 mg Thalidomide daily for the diet period (N + Th, HC + Th). LADs were scanned with micro-CT (20 microm cubic voxel size) to determine VV spatial density (#/mm2). Fresh-frozen coronary tissue was used for western blotting (VEGF, TNF-alpha, LOX-1, Ikappabetaalpha and Gro-alpha) and electrophoretic mobility shift assay (EMSA, NFkappabeta). Treatment with Thalidomide preserved VV spatial density [2.7 +/- 0.3 (N), 6.4 +/- 0.7 (HC), 3.5 +/- 0.8 (HC + Th); p = ns HC + Th vs. N] and inhibited the expression of VEGF, TNF-alpha and LOX-1, but not NFkappabeta activity in the coronary vessel wall. Immunofluorescence analyses revealed co-localization of vWF but not SMA and NFkappabeta, TNF-alpha as well as VEGF in HC and HC + Th coronaries. Intima-media thickness was significantly inhibited in HC + Th compared to HC. Serum levels of hs-CRP and TNF-alpha did not differ among the groups. Our study supports a role of VV neovascularization in the development of and a therapeutic potential for anti-angiogenic intervention in early atherosclerosis.

Serial Contrast-Enhanced Cardiac Magnetic Resonance Imaging Demonstrates Regression of Hyperenhancement Within the Coronary Artery Wall in Patients After Acute Myocardial Infarction

Our aim was to determine whether serial contrast-enhanced cardiac magnetic resonance (CE-CMR) is useful for the characterization of tissue signal changes within the coronary vessel wall in patients after acute myocardial infarction (AMI). Inflammation plays a key role in the development of AMI. CE-CMR of the vessel wall has been found useful for the characterization of inflammatory tissue signal changes in patients with carotid artery stenosis, giant cell arteritis, or Takayasu's arteritis; however, it has never been serially performed in the coronary artery wall in patients with acute and chronic myocardial infarction using a gadolinium-based contrast medium and compared with systemic markers of inflammation. CE-CMR using a T1-weighted 3-dimensional gradient echo inversion recovery sequence of the coronary artery wall and 0.2 mmol/kg of gadolinium-diethylenetriaminepentaacetic acid was performed in 10 patients with AMI 6 days and 3 months after coronary intervention and in 9 subjects without coronary artery disease on invasive coronary angiography. Contrast-to-noise ratio (CNR) within the coronary artery wall was quantified in comparison with blood signal. Patients with AMI demonstrated a significantly increased coronary vessel wall enhancement 6 days after infarction compared with normal subjects (CNR 7.8 +/- 4.4 vs. 5.3 +/- 3.2, p < 0.001). Three months after infarction, CNR decreased to 6.5 +/- 4.7 (p < 0.03). This decrease paralleled declines in C-reactive protein. Angiographically normal segments showed no contrast changes, but CNR significantly decreased in stenotic segments, from 10.9 +/- 3.8 to 6.8 +/- 5.0 (p < 0.002), resulting in a reduction of enhanced segments from 70% to 25% (p < 0.01). Serial CE-CMR identified changes in spatial extent and intensity of coronary contrast enhancement in patients after AMI. This technique may be useful for the characterization of transient coronary tissue signal changes, which may represent edema or inflammation during the post-infarction phase. In addition, CE-CMR may offer the potential for visualization of inflammatory activity in atherosclerosis associated with acute coronary syndromes.

The Late Na+ Current (INa) Inhibitor Ranolazine Attenuates Effects of Palmitoyl-L-Carnitine to Increase Late INa and Cause Ventricular Diastolic Dysfunction

Palmitoyl-L-carnitine (PC), an ischemic metabolite, causes cellular Na(+) and Ca(2+) overload and cardiac dysfunction. This study determined whether ranolazine [(+/-)-1-piperazineacetamide, N-(2,6-dimethylphenyl)-4-[2-hydroxy-3-(2-methoxyphenoxy)propyl]-] attenuates PC-induced Na(+) current and ventricular contractile dysfunction of the isolated heart. PC (4 microM, 30 min) increased late Na(+) current by 1034 +/- 349% in guinea pig isolated ventricular myocytes; ranolazine (10 microM) and tetrodotoxin (TTX, 3 microM) significantly attenuated this effect of PC. PC increased left ventricular end-diastolic pressure (LVEDP), coronary perfusion pressure (CPP), wall stiffness, and cardiac lactate and adenosine release from the isolated heart. Ranolazine (10 microM) significantly reduced the PC-induced increase in LVEDP by 72 +/- 6% (n = 6, p < 0.001), reduced left ventricular wall stiffness, and attenuated the PC-induced increase of CPP by 53 +/- 10% (n = 6-7, p < 0.05). Ranolazine (10 microM) reduced the PC-induced increases of lactate and adenosine release by 70 +/- 8 and 81 +/- 5%, respectively (n = 6, p <or= 0.05 for both). TTX (2 microM) significantly (p < 0.05) reduced PC-induced increases of CPP and LVEDP. Pretreatment of isolated myocytes or hearts with the free radical scavenger tiron (4,5-dihydroxy-1,3-benzenedisulfonic acid, disodium salt) (1 mM) significantly reduced the effects of PC to cause increases of late Na(+) current and LVEDP, respectively, but unlike ranolazine or TTX, tiron did not reverse increases of late Na(+) current and LVEDP caused by PC. In summary, ranolazine and TTX, inhibitors of the late Na(+) current, attenuated the PC-induced ventricular contractile dysfunction and increase of coronary resistance in the guinea pig isolated heart.

Positive Remodeling of the Coronary Arteries Detected by Magnetic Resonance Imaging in an Asymptomatic Population: MESA (Multi-Ethnic Study of Atherosclerosis)

The purpose of this study was to assess coronary arterial remodeling as a marker of subclinical atherosclerosis using coronary wall magnetic resonance imaging (MRI) in an asymptomatic population-based cohort.In early atherosclerosis, compensatory enlargement of both the outer wall of the vessel as well as the lumen, termed compensatory enlargement or positive remodeling, occurs before luminal narrowing.One hundred seventy-nine participants in the MESA (Multi-Ethnic Study of Atherosclerosis) trial were evaluated using black-blood coronary wall MRI. Coronary cross-sectional area (vessel size), lumen area, and mean wall thickness of the proximal coronary arteries were measured.Men had a greater vessel size, lumen area, and mean wall thickness than women (38.3 +/- 11.3 mm2 vs. 32.6 +/- 9.4 mm2, 6.7 +/- 3.2 mm2 vs. 5.3 +/- 2.4 mm2, and 2.0 +/- 0.3 mm vs. 1.9 +/- 0.3 mm, respectively, p < 0.05). No significant coronary artery narrowing was present by magnetic resonance angiography. Overall, coronary vessel size increased 25.9 mm2 per millimeter increase in coronary wall thickness, whereas lumen area increased only slightly at 3.1 mm2 for every millimeter increase in wall thickness (difference in slopes, p < 0.0001). Adjusting for age and sex, participants with an Agatston score >0 were more likely to have wall thickness >2.0 mm (odds ratio: 2.0, 95% confidence interval: 1.01 to 3.84).Coronary wall MRI detected positive arterial remodeling in asymptomatic men and women with subclinical atherosclerosis.

Low vasa vasorum densities correlate with inflammation and subintimal thickening: Potential role in location—Determination of atherogenesis

Objectives To assess the role of coronary vasa vasorum (VV) spatial distribution in determining the location of early atherosclerotic lesion development. Methods and results Six, 3-month-old, female, crossbred swine were fed 2% high-cholesterol (HC) diet for 3 months prior to euthanasia. Six other pigs were fed normal diet (N) for the entire 6 months. Right coronary arteries were harvested and scanned intact with micro-CT (20 μm cubic-voxel-size). After scanning, randomly selected cross-sectional histological sections were stained for nuclear-factor kappaB (NF-κB), hypoxia-inducible factor-1alpha (HIF-1α), macrophages, von-Willebrand-factor, dihydroethidium (DHE), tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6). The number of positive stained cells, as well as intima-to-media ratio, were compared with VV density (#/mm 2) obtained from micro-CT images (which closely matched the location of the histological sections) in each of four equal quadrants of the coronary vessel wall. In normal, as well as HC pigs, the number of NF-κB ( r = 0.73 and 0.70), HIF-1α ( r = 0.74 and 0.77), TNF-α ( r = 0.58 and 0.72) and IL-6 ( r = 0.70 and 0.72) positive cells as well as the expression of DHE (Kendall tau coefficient −0.64 and −0.63) inversely correlated with VV density. In HC the VV density also inversely correlated with intima/media ratios ( r = 0.65). Conclusions Our data suggest that low VV density territories within the coronary vessel wall are susceptible to hypoxia, oxidative stress and microinflammation and may therefore be starting points of early atherogenesis.

A study of coronary artery rotational motion with dense scale-space optical flow in intravascular ultrasound

This paper describes a novel method for estimating tissue motion in two-dimensional intravascular ultrasound (IVUS) images of a coronary artery. It is based on the classical Lukas–Kanade (LK) algorithm for optical flow (OF). The OF vector field quantifies the amount of misalignment between two consecutive frames in a sequence of images. From the theoretical standpoint, two fundamental improvements are proposed in this paper. First, using a simplified representation of the vessel wall as a medium with randomly distributed scatterers, it was shown that the OF equation satisfies the integral brightness conservation law. Second, a scale-space embedding for the OF equation was derived under the assumption of spatial consistency in IVUS acquisitions. The spatial coherence is equivalent to a locally affine motion model. The latter effectively captures and appropriately describes a complex deformation pattern of the coronary vessel wall under the varying physiological conditions (i.e. pulsatile blood pressure). The accuracy of OF tracking was estimated on the tissue-mimicking phantoms subjected to the controlled amount of angular deviation. Moreover, the performance of the classical LK and proposed approach was compared using the simulated IVUS images with an atherosclerotic lesion. The experimental results showed robust and reliable performance of up to 5° of rotation, which is within the plausible range of circumferential displacement of the coronary arteries. Subsequently, the algorithm was used to analyze vessel wall motion in 18 IVUS pullbacks from 16 patients. The in vivo experiments revealed that the motion of coronary arteries is primarily determined by the cardiac contraction.

Coronary Vessel Wall Evaluation by Magnetic Resonance Imaging in the Multi-Ethnic Study of Atherosclerosis

Coronary artery wall magnetic resonance imaging (MRI) has been developed to assess coronary lumen diameter and wall thickness. The purpose of this study was to evaluate the physiological parameters that affect the measures of coronary wall thickness using black-blood MRI pulse sequences. Eighty-seven participants (38 men and 49 women) of the Multi-Ethnic Study of Atherosclerosis were enrolled in the coronary artery wall MRI study. Cine 4-chamber imaging was used to determine the coronary artery rest period. Free-breathing whole-heart magnetic resonance angiography with motion adaptor navigator was performed to localize the coronary arteries in 64 participants. Cross-sectional free-breathing black-blood images were acquired using electrocardiogram-gated, turbo spin echo sequence. Imaging parameters were as follows: repetition time = 2 R-R intervals, time to echo = 33 milliseconds, echo train length = 13, bandwidth = 305 Hz/pixel, matrix = 416 x 416, field of view = 420 x 420 mm, and slice thickness = 4 to 5 mm. Imaging was completed in 215 (92%) of 234 coronary segments; 9 participants had incomplete scans. Mean age was 62.6 +/- 8.4 years (range, 45-81 years). Mean body mass index was 29.2 +/- 5.9 kg/m2. A higher proportion of images with quality of "good" was seen in the right coronary artery (40.5%) compared to the left main and left anterior descending coronary arteries (31.9% and 26.4%, respectively). There was a very good agreement between observers in the image quality scores (kappa = 0.79, P < 0.001). Lower heart rate, male sex, and longer coronary rest period were associated with higher image quality score (P < 0.05). Signal-to-noise ratio was higher in participants with Agatston calcium score of more than 10 in the right coronary and left main arteries (48.5 vs 69.7, P = 0.001; and 53.4 vs 61.6, P = 0.032, respectively). Improved depiction of the coronary artery wall with MRI is related to coronary rest period and atherosclerotic plaque burden as measured by calcium score and inversely related to heart rate. Because longer coronary artery rest periods are associated with improved image quality both for angiography with MRI and coronary artery wall imaging, heart rate-lowering methods in association with these techniques appear to be a logical application.

Visualization of Coronary Arterial Wall Based on Maximum Intensity Fusion of Whole-Heart MR Angiograms and Water Suppression SPIR 3D T1 TFE Images

We estimated the coronary artery wall using maximum intensity fusion (MIF) of whole-heart magnetic resonance (MR) angiography (WHCA) and water suppression-spectral presaturation with inversion recovery (WS-SPIR) 3D T(1)-weighted turbo field echo (3DT(1) TFE). We created a phantom using a wall of plastic bottles varied with plastic tapes measuring 0.4 to 3.0 mm thick (0-14 sheets) by vernier caliper and compared widths with those on profile curves. In 3 patients, to clarify the capacity to visualize the coronary wall in vulnerable plaque, we acquired WS-SPIR 3D T(1) TFE and WS-spectral attenuation with inversion recovery (SPAIR) (inversion time [TI] 400 ms) 3D T(1) TFE images of carotid vulnerable plaque; also termed "lipid-rich plaque," vulnerable plaque is considered to be visualized in high intensity. We utilized the same geometric parameters and rest period on WHCA as for WS-SPIR 3D T(1) TFE. We obtained MIF of WHCA and WS-SPIR 3D T(1) TFE and measured thickness of the right coronary artery (RCA) wall on the profile curve in 18 cases. The widths of the dip of the lower third of the bottom to head on the profile curve were consistent with actual measurement at 1-2 mm, the usual coronary artery wall thickness. Carotid plaques of high intensity by T(1)-weighted black-blood (T(1)BB) and T(2)-weighted BB (T(2)BB) methods showed high intensity on WS-SPAIR (TI 400 ms) 3D T(1) TFE and low intensity on WS-SPIR 3D T(1) TFE. With or without vulnerable plaque in the coronary artery wall, MIF of WHCA and WS-SPIR 3D T(1) TFE reflected the coronary artery wall. We obtained bands of low intensity in MIF between epicardial fat of WS-SPIR 3D T(1) TFE and coronary artery lumen of WHCA all but mid RCA in all 18 cases. We were unable to detect mid RCA in 5 cases. The outline of the obstructed mid RCA in 1 case was clear in WS-SPIR 3D T(1) TFE. The higher velocity of RCA movement caused blurring in another 4 cases in both WHCA and WS-SPIR 3D T(1) TFE. Those wall thickness of proximal or mid RCA averaged 1.3+/-0.2 mm. Bands of low intensity between epicardial fat and coronary artery lumen on MIF of WHCA and WS-SPIR 3D T(1) TFE can reflect the coronary artery wall.

Relationship Between Coronary Artery Wall Thickness Measured by 64-Slice Multidetector Computed Tomography and Cardiovascular Risk Factors

Recent studies have demonstrated the quantitative ability of contrast-enhanced multidetector computed tomography (MDCT) to evaluate not only the vessel lumen but also coronary plaque. The aim of this study was to assess the association between coronary wall thickness quantified by 64-slice MDCT and cardiovascular risk factors. A total of 149 subjects with suspected coronary artery disease were scanned by contrast-enhanced 64-slice MDCT. The maximum coronary wall thickness of each proximal segment was measured and associations with baseline coronary risk factors were analyzed. The mean maximum wall thickness of all 149 patients was 0.7+/-0.3 mm and there was a significant positive correlation with age (P<0.001) and hemoglobin (Hb) A1c (P=0.001). Patients with hypertension (0.8+/-0.3 vs 0.7+/-0.3 mm, P=0.024) and diabetes (0.9+/-0.4 vs 0.7+/-0.3 mm, P=0.002) had thicker walls than those without. Multivariate linear regression analysis demonstrated that both risk factors were independently correlated with mean maximum wall thickness. Coronary wall thickness measured by 64-slice MDCT is associated with age and HbA1c, so may add useful information to cardiovascular risk stratification.

Non-invasive Coronary Angiography: the Role, Limitations and Future of 64-Slice Spiral Computed Tomography Coronary Angiography

Noninvasive coronary imaging can now be accomplished with use of computed tomography coronary angiography (CTCA) which is becoming an important alternative to invasive coronary angiography in selected patients. CTCA is best applied in patients with intermediate risk for coronary artery disease (CAD). It is a reliable technique for patient screening, thus reducing the number of unnecessary invasive coronary angiography examinations, but cannot yet replace invasive coronary angiography in all patients suspected of CAD. Concerns remain regarding the radiation exposure, which is expected to be significantly reduced with the availability of improved technology and newer multi-channel scanners offering the potential to image the entire heart during a single heartbeat. The current status of CTCA is herein briefly reviewed. I N T R O D U C T I O N Conventional selective X-ray coronary angiography (CA) remains the undisputed standard of reference for the assessment of the lumen of coronary arteries. However, this is an invasive procedure with a small but not negligible health risk that needs even short hospitalization and causes patient discomfort. Among the more than 2.5 million examinations of CA performed annually in U.S.A. and Europe, approximately 25% do not reveal essential findings and more than 40% are not followed by any kind of interventional or surgical procedure. On the other hand, CA does not provide any information concerning the coronary wall, while almost 80% of deadly myocardial infarctions are atributed to vulnerable plaques which did not cause hemodynamically severe stenoses. Thus, an effort for the development of non-invasive techniques for visualization of the coronary arteries is justified. Ideally, such a technique should be capable of reliably excluding or detecting significant stenoses of the coronary lumen and, at the same time, of assessing the coronary wall and plaque structure. By means of computed tomography (CT), this goal is being accomplished with two techniques; electron beam CT (EBCT) and multislice spiral CT (MSCT). EBCT was the first CT modality capable to provide diagnostic images of the RevIew CT, MRI & PET/CT Department, “Hygeia” Hospital, Athens, Greece HOSPITAL CHRONICLES 2009, 4(3): 105–109 Correspondence to: Arkadios C. Roussakis, MD CT, MRI & PET/CT Department “Hygeia” Hospital Athens, Greece E-mail: arkrous@hol.gr Key wORDS: coronary angiography; computed tomography; coronary artery disease; radiation exposure; coronary

Phase-sensitive black-blood coronary vessel wall imaging

Phase-sensitive black-blood coronary vessel wall imaging