In vivo magnetic resonance evaluation of associations between aortic atherosclerosis and both risk factors and coronary artery disease in patients referred for coronary angiography

Prevalence and distribution of aortic plaque by sex and age group among community-dwelling adults

RATIONALE AND OBJECTIVES

Atherosclerosis of the aorta is associated with increased risk of cardiovascular mortality and vascular events. We aim to describe the prevalence and distribution of non-calcified atherosclerotic plaque in the descending aorta as quantified by noncontrast cardiovascular magnetic resonance (CMR) in a community-dwelling cohort of adults.

MATERIALS AND METHODS

We used CMR to quantify noncalcified aortic plaque in 1726 participants (aged 65 ± 9 years, 46.7% men) from the Cohort Study Offspring cohort. ECG-gated, fat-suppressed, T2-weighted, black blood turbo spin echo sequence was used to acquire 36 transverse slices covering the descending aorta from just below the arch to the aortoiliac bifurcation. Plaque was defined as discrete luminal protrusions ≥1 mm; these were manually traced, then summed to determine total descending aortic plaque (DAP) and segmental thoracic and abdominal aortic plaque (TAP, AAP). Participants were stratified by sex and age group (<55, 55-64, 65-74, ≥75y). A healthy referent group (without clinical cardiovascular disease, smoking, diabetes, impaired renal function; (N = 768, 43.8% men) was used to determine upper 90th percentile cutpoints for DAP and AAP which were then applied to the overall study cohort.

RESULTS

Prevalence of DAP was similar between men (47.3%) and women (48.9%), p = 0.50, as was AAP prevalence (men: 44.5%, women: 46.7%, p = 0.16); TAP was less prevalent in both sexes (men: 8.9%, women: 7.1%, p = 0.15). Both prevalence and burden of DAP, AAP and TAP increased with advancing age.

CONCLUSION

Noncalcified plaque prevalence, visualized on CMR, in community-dwelling adults is similar between the sexes, and both prevalence and burden of aortic plaque increase with greater age.

Plaque Vulnerability as Assessed by Radiofrequency Intravascular Ultrasound in Patients with Valvular Calcification

Background

Cardiac valvular calcification is associated with the overall coronary plaque burden and considered an independent cardiovascular risk and prognostic factor. The purpose of this study was to evaluate the relationship between the presence of valvular calcification and plaque morphology and/or vulnerability.

Methods

Transthoracic echocardiography was used to assess valvular calcification in 280 patients with coronary artery disease who underwent radiofrequency intravascular ultrasound (Virtual Histology IVUS, VH-IVUS). A propensity score–matched cohort of 192 patients (n = 96 in each group) was analyzed. Thin-capped fibroatheroma (TCFA) was defined as a necrotic core (NC) >10% of the plaque area with a plaque burden >40% and NC in contact with the lumen for ≥3 image slices. A remodeling index (lesion/reference vessel area) >1.05 was considered to be positive.

Results

Patients were divided into two groups: any calcification in at least one valve (152 patients) vs. no detectable valvular calcification (128 patients). Groups were similar in terms of age, risk factors, clinical diagnosis, and angiographic analysis after propensity score-matched analysis. Gray-scale IVUS analysis showed that the vessel size, plaque burden, minimal lumen area, and remodeling index were similar. By VH-IVUS, % NC and % dense calcium (DC) were greater in patients with valvular calcification (p = 0.024, and p = 0.016, respectively). However, only % DC was higher at the maximal NC site by propensity score-matched analysis (p = 0.029). The frequency of VH-TCFA occurrence was higher depending on the complexity (p = 0.0064) and severity (p = 0.013) of valvular calcification.

Conclusions

There is a significant relationship between valvular calcifications and VH-IVUS assessment of TCFAs. Valvular calcification indicates a greater atherosclerosis disease complexity (increased calcification of the coronary plaque) and vulnerable coronary plaques (higher incidence of VH-TCFA).

Association between abdominal aortic plaque and coronary artery disease

OBJECTIVE

Currently, the association between abdominal aortic plaques and coronary artery disease (CAD) has not yet been clarified clearly. The purpose of this study was to determine the prevalence of abdominal aortic plaques by ultrasound imaging and to explore its association with CAD in patients undergoing coronary angiography.

METHODS

Between October 2014 and June 2015, a prospective study was conducted in the Department of Cardiology at Guangdong General Hospital, Guangzhou, People's Republic of China. Ultrasound scanning of the abdominal aortas was performed in 1,667 consecutive patients undergoing coronary angiography. Clinical characteristics and coronary profile were collected from the patients.

RESULTS

Of the 1,667 study patients (male, 68.9%; mean age, 63±11 years) undergoing coronary angiography, 1,268 had CAD. Compared with 399 patients without CAD, 1,268 patients with CAD had higher prevalence of abdominal aortic plaques (37.3% vs 17%, P<0.001). In multivariate analysis, abdominal aortic plaques served as independent factors associated with the presence of CAD (odds ratio =2.08; 95% confidence interval =1.50-2.90; P<0.001). Of the 1,268 patients with CAD, the prevalence of abdominal aortic plaques was 27.0% (98/363) in patients with one-vessel disease, 35.0% (107/306) in patients with two-vessel disease, and 44.7% (268/599) in patients with three-vessel disease. Stepwise increases in the prevalence of abdominal aortic plaque was found depending on the number of stenotic coronary vessels (P<0.001; P-value for trend <0.001). In an ordinal logistic regression model, abdominal aortic plaques served as independent factors associated with the severity of CAD according to the number of stenotic coronary vessels (P<0.001).

CONCLUSION

The prevalence of abdominal aortic plaques was higher in patients with CAD than in those without CAD. Abdominal aortic plaque was an independent factor associated with the presence and severity of CAD.

Cardiovascular magnetic resonance imaging-based computational fluid dynamics/fluid-structure interaction pilot study to detect early vascular changes in pediatric patients with type 1 diabetes

We hypothesized that pediatric patients with type 1 diabetes have cardiac magnetic resonance (CMR) detectable differences in thoracic aortic wall properties and hemodynamics leading to significant local differences in indices of wall shear stress, when compared with age-matched control subjects without diabetes. Pediatric patients with type 1 diabetes were recruited from Children's Hospital of Wisconsin and compared with controls. All underwent morning CMR scanning, 4-limb blood pressure, brachial artery reactivity testing, and venipuncture. Patient-specific computational fluid dynamics modeling with fluid-structure interaction, based on CMR data, determined regional time-averaged wall shear stress (TAWSS) and oscillatory shear index (OSI). Twenty type 1 diabetic subjects, median age 15.8 years (11.6-18.4) and 8 controls 15.4 years (10.3-18.2) were similar except for higher glucose, hemoglobin A1c, and triglycerides for type 1 diabetic subjects. Lower flow-mediated dilation was seen for those with type 1 diabetes (6.5) versus controls (7.8), p = 0.036. For type 1 diabetic subjects, the aorta had more regions with high TAWSS when compared to controls. OSI maps appeared similar. Flow-mediated dilation positively correlated with age at diabetes diagnosis (r = 0.468, p = 0.038) and hemoglobin A1c (r = 0.472, p = 0.036), but did not correlate with aortic distensibility, TAWSS, or OSI. TAWSS did not correlate with any clinical parameter for either group. CMR shows regional differences in aortic wall properties for young diabetic patients. Some local differences in wall shear stress indices were also observed, but a longitudinal study is now warranted.

Can aortic atherosclerosis or epicardial adipose tissue volume be used as a marker for predicting coronary artery disease?

PURPOSE

To investigate whether aortic atherosclerosis or epicardial adipose tissue (EAT) volume on multidetector computed tomography (CT) can predict the presence of significant coronary artery disease (CAD).

MATERIALS AND METHODS

Coronary CT angiography was performed in 202 cases of CAD that were known or based on suspicion. Based on coronary CT angiography results, the patients with significant stenosis (≥50%) and without significant stenosis (<50%) were compared in terms of demographic characteristics, traditional cardiovascular risk factors, aortic atherosclerosis, and EAT volume.

RESULTS

Significant coronary artery stenosis was detected in 92 cases (45.5%). Although EAT volume was higher in the patients with significant stenosis, the difference between the two groups was not statistically significant. The presence of calcification in the descending aorta was significantly higher in the patients with significant stenosis than the patients without significant stenosis (50.4% and 15.4%, respectively, p=0.0001). The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy rates of the presence of calcification in the descending aorta in predicting the presence of significant coronary artery stenosis were respectively found as 53.8%, 84.4%, 74.6%, 68.1%, and 70.3%. The sensitivity, specificity, PPV, NPV, and accuracy rates of the ≥2.45mm wall thickness of the descending aorta in predicting the presence of significant coronary artery stenosis were respectively found as 75.3%, 74.3%, 71.4%, 77.9%, and 74.8%.

CONCLUSION

There is a strong relationship between thoracic aortic atherosclerosis and CAD. However, the relationship between EAT volume and CAD is not significant. The presence of aortic atherosclerosis can be used as an additional marker together with traditional cardiovascular risk factors for predicting CAD.

Risk factor differences in calcified and noncalcified aortic plaque: the Framingham Heart Study

OBJECTIVE

The objective of this study was to determine the prevalence and risk factor (RF) correlates of aortic plaque (AP) detected by cardiovascular magnetic resonance (CMR), which mainly shows noncalcified plaques, and by noncontrast computed tomography (CT), which best depicts calcified plaques, in community-dwelling adults.

APPROACH AND RESULTS

A total of 1016 Framingham Heart Study Offspring cohort members (64 ± 9 years; 474 men) underwent CMR and CT of the aorta. Potential RFs for AP (age; sex; body mass index; blood pressure; low-density lipoprotein and high-density lipoprotein cholesterol; fasting glucose; C-reactive protein; prevalent hypertension, diabetes mellitus, smoking; use of antihypertensive, diabetes mellitus, or lipid-lowering drugs) were compared between participants, with zero versus nonzero AP by CMR and by CT. Candidate RFs attaining P<0.05 for difference with either imaging modality were entered into multivariable logistic regression models adjusting for age, sex, and other RFs. Odds ratios were calculated for modality-specific prevalence of AP. Associations between RFs and continuous measures of AP were assessed using Tobit regression. Prevalence of CMR and CT AP was 49% and 82%, respectively. AP burdens by CMR and CT were correlated, r=0.28, P<0.0001. Increasing age and smoking were associated with prevalent AP by both CMR and CT. Additionally, prevalent AP by CMR was associated with female sex and fasting glucose and prevalent AP by CT with hypertension treatment and adverse lipid profile.

CONCLUSIONS

AP by CMR and CT are both associated with smoking and increasing age, but other RFs differ between calcified and noncalcified AP. The relative predictive value of AP detected by CMR versus by CT for incident cardiovascular events remains to be determined.

Atherosclerotic biomarkers and aortic atherosclerosis by cardiovascular magnetic resonance imaging in the Framingham Heart Study

BACKGROUND

The relations between subclinical atherosclerosis and inflammatory biomarkers have generated intense interest but their significance remains unclear. We sought to determine the association between a panel of biomarkers and subclinical aortic atherosclerosis in a community-based cohort.

METHODS AND RESULTS

We evaluated 1547 participants of the Framingham Heart Study Offspring cohort who attended the 7th examination cycle and underwent both cardiovascular magnetic resonance imaging (CMR) and assays for 10 biomarkers associated with atherosclerosis: high-sensitivity C-reactive protein, fibrinogen, intercellular adhesion molecule-1, interleukin-6, interleukin-18, lipoprotein-associated phospholipase-A2 activity and mass, monocyte chemoattractant protein-1, P-selectin, and tumor necrosis factor receptor-2. In logistic regression analysis, we found no significant association between the biomarker panel and the presence of aortic plaque (global P=0.53). Using Tobit regression with aortic plaque as a continuous variable, we noted a modest association between biomarker panel and aortic plaque volume in age- and sex-adjusted analyses (P=0.003). However, this association was attenuated after further adjustment for clinical covariates (P=0.09).

CONCLUSIONS

In our community-based cohort, we found no significant association between our multibiomarker panel and aortic plaque. Our results underscore the strengths and limitations of the use of biomarkers for the identification of subclinical atherosclerosis and the importance of traditional risk factors.

MR imaging of the arterial vessel wall: molecular imaging from bench to bedside

Cardiovascular diseases remain the leading cause of morbidity and mortality in the Western world and developing countries. In clinical practice, in vivo characterization of atherosclerotic lesions causing myocardial infarction, ischemic stroke, and other complications remains challenging. Imaging methods, limited to the assessment luminal stenosis, are the current reference standard for the assessment of clinically significant coronary and carotid artery disease and the guidance of treatment. These techniques do not allow distinction between stable and potentially vulnerable atherosclerotic plaque. Magnetic resonance (MR) imaging is a modality well suited for visualization and characterization of the relatively thin arterial vessel wall, because it allows imaging with high spatial resolution and excellent soft-tissue contrast. In clinical practice, atherosclerotic plaque components of the carotid artery and aorta may be differentiated and characterized by using unenhanced vessel wall MR imaging. Additional information can be gained by using clinically approved nonspecific contrast agents. With the advent of targeted MR contrast agents, which enhance specific molecules or cells, pathologic processes can be visualized at a molecular level with high spatial resolution. In this article, the pathophysiologic changes of the arterial vessel wall underlying the development of atherosclerosis will be first reviewed. Then basic principles and properties of molecular MR imaging contrast agents will be introduced. Additionally, recent advances in preclinical molecular vessel wall imaging will be reviewed. Finally, the clinical feasibility of arterial vessel wall imaging at unenhanced and contrast material-enhanced MR imaging of the aortic, carotid, and coronary vessel wall will be discussed.

The relationship between neutrophil-to-lymphocyte ratio and vascular calcification in end-stage renal disease patients

Chronic inflammation was found to be correlated with coronary (CAC) and thoracic peri-aortic calcification (TAC) in end-stage renal disease (ESRD) patients. Neutrophil-to-lymphocyte ratio (NLR) was introduced as a potential marker to determine inflammation in cardiac and noncardiac disorders. Data regarding NLR and its association with TAC and CAC are lacking. We aimed to determine the relationship between NLR and vascular calcification in ESRD patients. This was a cross-sectional study involving 56 ESRD patients (22 females, 34 males; mean age, 49.9 ± 14.2 years) receiving peritoneal dialysis or hemodialysis for ≥6 months in the Dialysis Unit of Necmettin Erbakan University. TAC and CAC scores were measured by using an electrocardiogram-gated 64-multidetector computed tomography. NLR was calculated as the ratio of the neutrophils and lymphocytes. There was a statistically significant correlation between NLR, TACS and CACS in ESRD patients (r = 0.43, P = 0.001 and r = 0.30, P = 0.02, respectively). The stepwise linear regression analysis revealed that age, as well as NLR were independent predictors of TACS. However, increased age was the only independent predictor of CACS according to linear regression analysis. Simple calculation of NLR can predict vascular calcification in ESRD patients.

Three-dimensional imaging of the aortic vessel wall using an elastin-specific magnetic resonance contrast agent

OBJECTIVE

The aim of this study was to demonstrate the feasibility of high-resolution 3-dimensional aortic vessel wall imaging using a novel elastin-specific magnetic resonance contrast agent (ESMA) in a large animal model.

MATERIALS AND METHODS

The thoracic aortic vessel wall of 6 Landrace pigs was imaged using a novel ESMA and a nonspecific control agent. On day 1, imaging was performed before and after the administration of a nonspecific control agent, gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA; Bayer Schering AG, Berlin, Germany). On day 3, identical scans were repeated before and after the administration of a novel ESMA (Lantheus Medical Imaging, North Billerica, Massachusetts). Three-dimensional inversion recovery gradient echo delayed-enhancement imaging and magnetic resonance (MR) angiography of the thoracic aortic vessel wall were performed on a 1.5-T MR scanner (Achieva; Philips Medical Systems, the Netherlands). The signal-to-noise ratio and the contrast-to-noise ratio of arterial wall enhancement, including the time course of enhancement, were assessed for ESMA and Gd-DTPA. After the completion of imaging sessions, histology, electron microscopy, and inductively coupled plasma mass spectroscopy were performed to localize and quantify the gadolinium bound to the arterial vessel wall.

RESULTS

Administration of ESMA resulted in a strong enhancement of the aortic vessel wall on delayed-enhancement imaging, whereas no significant enhancement could be measured with Gd-DTPA. Ninety to 100 minutes after the administration of ESMA, significantly higher signal-to-noise ratio and contrast-to-noise ratio could be measured compared with the administration of Gd-DTPA (45.7 ± 9.6 vs 13.2 ± 3.5, P < 0.05 and 41.9 ± 9.1 vs 5.2 ± 2.0, P < 0.05). A significant correlation (0.96; P < 0.01) between area measurements derived from ESMA scans and aortic MR angiography scans could be found. Electron microscopy and inductively coupled plasma mass spectroscopy confirmed the colocalization of ESMA with elastic fibers.

CONCLUSION

We demonstrate the feasibility of aortic vessel wall imaging using a novel ESMA in a large animal model under conditions resembling a clinical setting. Such an approach could be useful for the fast 3-dimensional assessment of the arterial vessel wall in the context of atherosclerosis, aortic aneurysms, and hypertension.

Peri-aortic fat tissue thickness in peritoneal dialysis patients

BACKGROUND

Thoracic peri-aortic fat tissue (PFT) and epicardial adipose tissue (EAT) are metabolically active visceral fat deposits surrounding the thoracic aorta and the heart, respectively. Various studies have demonstrated a positive predictive value of both PFT and EAT for coronary artery disease in the general population. In the present study, we aimed to investigate PFT thickness and the independent predictors of PFT in peritoneal dialysis (PD) patients. ♢

METHODS

Our cross-sectional study enrolled 35 PD patients (10 women, 25 men) and 30 age-and-sex-matched healthy subjects (15 women, 15 men). We measured PFT, thoracic artery calcification (TAC), EAT, and coronary artery calcification (CAC) by electrocardiogram-gated 64-multi-detector computed tomography. ♢

RESULTS

The measured PFT, EAT, CAC, and TAC were significantly higher in the PD group than in the healthy subjects (p < 0.05 each). In the PD group, PFT and TAC were significantly correlated (r = 0.33, p = 0.007). Also, PFT measurements were positively correlated with EAT and total CAC in the PD and the control group alike (r = 0.58, p = 0.001 and r = 0.54, p = 0.01 respectively). A stepwise linear regression analysis revealed that age, duration of hypertension, and being a PD patient were independent predictors of PFT. ♢

CONCLUSIONS

Measured PFT was higher in PD patients than in healthy subjects and, in the PD population, was also shown to be related to calcification scores and EAT.

Atherosclerosis and arterial stiffness in obstructive sleep apnea--a cardiovascular magnetic resonance study

OBJECTIVE

Obstructive sleep apnoea (OSA) has been linked to cardiovascular risk factors, such as hypertension, and clinical cardiovascular endpoints. Our aim was to assess whether OSA is independently associated with atherosclerosis and vascular dysfunction as assessed by cardiovascular magnetic resonance (CMR).

METHODS

58 patients with OSA and 39 matched control subjects without OSA underwent CMR of the aorta and carotid arteries. Carotid and aortic wall thickness and aortic distensibility were measured. Multi-weighted, high resolution CMR imaging was used for carotid atheroma characterization according to the American Heart Association (AHA) atheroma classification, modified for CMR.

RESULTS

Carotid [1.47±0.03 mm vs. 1.26±0.05 mm, (P<0.01)] and aortic wall thickness [2.95±0.09 mm vs. 2.05±0.07 mm, (P<0.001)] were increased in patients with OSA compared to controls. Aortic distensibility was decreased in patients with OSA [3.62±0.3 vs. 4.75±0.2 mmHg(-1)×10(-3), (P<0.05)]. Prevalence of carotid plaque, average carotid atheroma class, and prevalence of high risk features of carotid atheroma were increased in patients with OSA (P<0.005 for all). On multivariate analysis, Oxygen desaturation index (ODI) emerged as an independent predictor of carotid and aortic wall thickness, but not of aortic stiffness.

CONCLUSIONS

OSA is associated with increased carotid and aortic atheroma burden and with advanced, high risk carotid atherosclerotic plaques, but not with aortic stiffening.

Detection of subclinical atherosclerosis in familial hypercholesterolemia using non-invasive imaging modalities

OBJECTIVES

To investigate the extent of subclinical atherosclerosis in asymptomatic familial hypercholesterolemia (FH) patients using non-invasive images techniques.

PATIENTS, METHODS AND RESULTS

The atherosclerotic burden of 36 molecularly defined FH patients (18 males, 45.7±10.9 years) without evidence of cardiovascular disease receiving lipid-lowering treatment and 19 (47.8±11.3 years) controls was investigated. Descending thoracic aorta magnetic resonance imaging (MRI) was performed in a 1.5 T equipment with T1 and T2 sequences to characterize atherosclerotic plaques and to measure aortic wall volumen. Carotid intima-media thickness (cIMT) and presence of plaques were measured using B-mode carotid ultrasound. Mean aortic wall volumen, cIMT and atherosclerotic plaques in aorta were significantly higher in FH cases (P<0.001). A significant correlation between aortic wall volume and cIMT was observed (P<0.01). Aortic MRI detected plaques in 94% and carotid ultrasound in 14% of cases. Lipid-rich plaques were observed only in FH cases (33%) and were associated with family history of premature coronary artery disease (P<0.05).

CONCLUSIONS

Asymptomatic middle-aged FH patients have significantly higher atherosclerotic burden than controls. cIMT has shown a significant correlation with aortic wall volume and MRI allowed the detection of lipid-rich plaques in FH subjects that were associated with family history of premature coronary artery disease.

Associations between serum lipoprotein(a) levels and the severity of coronary and aortic atherosclerosis

To elucidate the associations between Lp(a) levels and coronary and aortic atherosclerosis, we performed aortic MRI in 143 patients undergoing coronary angiography. Severity of aortic atherosclerosis was represented as plaque scores. Of the 143 patients, 104 had coronary artery disease (CAD). Thoracic and abdominal aortic plaques were found in 89 and 131 patients. Lp(a) levels increased stepwise with the number of stenotic coronary vessels: 15.7 (CAD(-)), 21.2 (1-vessel), 21.4 (2-vessel), and 22.9 mg/dl (3-vessel) (P<0.05). For aortic atherosclerosis, 143 patients were divided into quartiles by plaque scores. Lp(a) did not differ among quartiles of thoracic plaques: 17.1, 19.0, 23.5, and 21.2 mg/dl (P=NS), whereas Lp(a) increased stepwise with quartiles of abdominal plaques: 17.1, 19.2, 19.1, and 24.0 mg/dl (P<0.05). Lp(a) was an independent factor for CAD and abdominal aortic plaques, but not thoracic plaques. Thus, Lp(a) levels were associated with aortic atherosclerosis, especially in abdominal aorta, as well as coronary atherosclerosis.

Zoom imaging for rapid aortic vessel wall imaging and cardiovascular risk assessment

PURPOSE

To demonstrate the utility of a "reduced field-of-view" (zoom imaging) technique to accelerate free-breathing, ECG-triggered, turbo-spin-echo black-blood sequences, which have been previously described to detect subclinical aortic atherosclerosis.

MATERIALS AND METHODS

Fifteen healthy volunteers underwent MRI of the thoracic and abdominal aorta. Imaging with the conventional full field-of-view sequence was compared with zoom imaging. Total scan time, image quality (i.e., contrast-to-noise ratio and vessel wall sharpness) and vessel wall thickness were analyzed. A subgroup of 10 volunteers also underwent acceleration of imaging using sensitivity encoding (SENSE) for comparison.

RESULTS

Zoom imaging significantly reduced imaging time from a mean of 41 ± 9 min (conventional imaging) to 15 ± 0.5 min (P<0.01). There was no difference in image quality between conventional and zoom imaging with respect to CNR (10.1 ± 6 versus 10.1 ± 6) or vessel wall sharpness (38 ± 4% versus 39 ± 4%). Furthermore, Bland Altman plots showed excellent agreement in vessel wall thickness measurements using the two methods. In comparison, SENSE not only reduced CNR but also resulted in underestimation of vessel wall thickness compared with the conventional sequence.

CONCLUSION

Zoom imaging allows accurate and time-efficient imaging of the abdominal and thoracic aorta for cardiovascular risk prediction. In this application, it is preferable to SENSE.

Epicardial adipose tissue thickness predicts descending thoracic aorta atherosclerosis shown by multidetector computed tomography

Human epicardial adipose tissue (EAT) is a type of visceral adipose tissue functioning as an endocrine organ by secreting hormones and adipocytokines which have an important role in the atherosclerotic process. In this study, we aimed to assess the relationship between EAT measured by dual source multidetector computed tomography (MDCT) and descending thoracic aorta (DTA) atherosclerosis. A total of 148 patients who underwent MDCT for the evaluation of coronary artery disease were enrolled in this study. Thickness of the EAT was measured on contrast enhanced multiplanar reformat images with parasternal short axis view at basal, mid-ventricular and apical levels and horizontal long axis view. The atherosclerotic plaque was scored from 0 to 4 points by the percentage of the luminal surface at the cross sectional area of proximal, mid and distal segments of descending aorta. Among the study population, 84 (56.8%) were male and age was (mean ± standart deviation) 56.9 ± 11.7 years. In patients with critical coronary atherosclerosis, DTA atherosclerosis had a significant relationship with EAT (P = 0.012). Multivariate linear regression analysis revealed that in addition to critical coronary stenosis, age and total epicardial fat thickness were associated with aortic atherosclerosis (β value, 0.058 and 0.035; t value, 4.74 and 2.28, respectively; P < 0.05) after adjustment for traditional cardiovascular risk factors. In this study we demonstrated that atherosclerotic plaque burden of DTA was associated with the amount of EAT thickness among patients with suspected CAD shown by MDCT. Further large scale prospective studies are needed to address the interaction of EAT as well as the mediators of inflammation and adipocytokines with the development of atherosclerotic plaques in aorta and effects on cardiovascular outcomes.

Imaging of atherosclerosis: magnetic resonance imaging

Atherosclerosis and its thrombotic complications are the major cause of morbidity and mortality in the industrialized countries. Despite advances in our understanding of the pathophysiology, pathogenesis, and new treatment modalities, the absence of an adequate non-invasive imaging tool for early detection limits both the prevention and treatment of patients with various degrees and anatomical localizations of atherothrombotic disease. An ideal clinical imaging modality for atherosclerotic vascular disease should be safe, inexpensive, non-invasive or minimally invasive, accurate, and reproducible, and the results should correlate with the extent of atherosclerotic disease and have high predictive values for future clinical events. High-resolution magnetic resonance imaging (MRI) has emerged as the most promising technique for studying atherothrombotic disease in humans in vivo. Most importantly, MRI allows for the characterization of plaque composition, i.e. the discrimination of lipid core, fibrosis, calcification, and intraplaque haemorrhage deposits. Magnetic resonance imaging also allows for the detection of arterial thrombi and in defining thrombus age. Magnetic resonance imaging has been used to monitor plaque progression and regression in several animal models of atherosclerosis and in humans. Emerging MRI techniques capable of imaging biological processes, including inflammation, neovascularization, and mechanical forces, may aid in advancing our understanding of the atherothrombotic disease. Advances in diagnosis do prosper provided they march hand-in-hand with advances in treatment. We stand at the threshold of accurate non-invasive assessment of atherosclerosis. Thus, MRI opens new strategies ranging from screening of high-risk patients for early detection and treatment as well as monitoring of the target lesions for pharmacological intervention. Identification of subclinical atherosclerosis and early treatment initiation has the potential to surpass conventional risk factor assessment and management in terms of overall impact on cardiovascular morbidity and mortality. Such strategy is currently under clinical investigation.

Sex, race, and age distributions of mean aortic wall thickness in a multiethnic population-based sample

BACKGROUND

Reference values and age-related changes of the wall thickness of the abdominal aorta have not been described in the general population. We characterized age-, race-, and gender-specific distributions, and yearly rates of change of mean aortic wall thickness (MAWT), and associations between MAWT and cardiovascular risk factors in a multi-ethnic population-based probability sample.

METHODS

Magnetic resonance imaging measurements of MAWT were performed on 2466 free-living white, black, and Hispanic adult subjects. MAWT race/ethnicity- and gender-specific percentile values across age were estimated using regression analyses.

RESULTS

MAWT was greater in men than in women and increased linearly with age in all the groups and across all the percentiles. Hispanic women had the thinnest and black men the thickest aortas. Black men had the highest and white women the lowest age-related MAWT increase. Age, gender, ethnicity, smoking status, systolic blood pressure, low-density lipoprotein-cholesterol levels, high-density lipoprotein-cholesterol levels, and fasting glucose levels were independent predictors of MAWT.

CONCLUSIONS

Age, gender, and racial/ethnic differences in MAWT distributions exist in the general population. Such differences should be considered in future investigations assessing aortic atherosclerosis and the effects of anti-atherosclerotic therapies.

Aortic atherosclerosis predicts the extent and severity of coronary atherosclerosis detected by multidetector computed tomography coronary angiography

We investigated the association between atherosclerosis of the thoracic aorta and the severity and extent of coronary atherosclerosis detected by multidetector computed tomography (MDCT) coronary angiography. In 122 patients, atherosclerotic plaque was scored from 0 to 4 points by the percentage of the luminal surface at the cross-sectional area of proximal, mid, and distal segments of the descending aorta. Critical coronary atherosclerosis was defined as lesions causing >50% luminal narrowing. Atherosclerotic plaque score of the descending aorta was associated with the severity (noncritical: 2.95 +/- 1.45 vs critical: 4.09 +/- 2.25, P < .001) and extent of coronary atherosclerosis (Kruskal-Wallis test, P < .005). Logistic regression revealed that aortic plaque score was as an independent risk factor associated with the severity of coronary artery disease (OR 1.32, 95% CI 1.01-1.73, P <.05). Atherosclerotic plaque burden of the descending aorta was associated with the extent and severity of coronary atherosclerosis.

The aorta wall of patients presenting to the emergency department with acute myocardial infarction by cardiac magnetic resonance

BACKGROUND

Inflammation has been shown to be a major component in the pathophysiology of acute coronary syndrome (ACS). In patients presenting with acute myocardial infarction (AMI), a critical component of the ACS spectrum, multiple coronary arteries are involved during this inflammatory process. In addition to the coronary vasculature, the inflammatory cascade has also been shown to affect the carotid arteries and possibly the aorta.

PURPOSE

To assess the involvement of the aorta during AMI by cardiac magnetic resonance (CMR).

METHODS

We prospectively evaluated the aortic wall by CMR in 123 patients. 78 patients were enrolled from the emergency department (ED), who presented with chest pain and were classified as either: (1) AMI: elevated troponin levels and typical chest pain or (2) non-cardiac chest pain (CP): negative troponins and a normal stress test or normal cardiac catheterization. We compared these 2 groups to a group of 45 asymptomatic diabetic patients. The descending thoracic aortic wall area (AWA) and maximal aortic wall thickness (AWT) were measured using a double inversion recovery T-2 weighted, ECG-gated, spin echo sequence by CMR.

RESULTS

Patients with AMI were older, more likely to smoke, had a higher incidence of claudication, and had higher CRP levels. The AWA and maximal AWT were greater in patients who presented to the ED with ACS (2.11+/-0.17 mm(2), and 3.17+/-0.19 mm, respectively) than both patients presenting with non-cardiac CP (1.52+/-0.58 mm(2), p<0.001; and 2.57+/-0.10 mm, p<0.001) and the diabetic patients (1.38+/-0.58 mm(2), p<0.001; and 2.30+/-0.131 mm, p<0.001). The difference in the aortic wall characteristics remained significant after correcting for body mass index, hyperlipidemia, statins and C-reactive protein. There was no difference in maximal AWT or AWA between patients with non-cardiac CP and patients with diabetes.

CONCLUSION

Patients with AMI have a significantly greater maximal aortic wall thickness and area compared to patients with non-cardiac CP. Longitudinal studies are needed to assess whether this increase is due to inflammation or a higher atherosclerotic burden.

Variations in atherosclerosis and remodeling patterns in aorta and carotids

BACKGROUND

Atherosclerosis is a progressive disease that causes vascular remodeling that can be positive or negative. The evolution of arterial wall thickening and changes in lumen size under current "standard of care" in different arterial beds is unclear. The purpose of this study was to examine arterial remodeling and progression/regression of atherosclerosis in aorta and carotid arteries of individuals at risk for atherosclerosis normalized over a 1-year period.

METHODS

In this study, 28 patients underwent at least 2 black-blood in vivo cardiovascular magnetic resonance (CMR) scans of aorta and carotids over a one-year period (Mean 17.8 +/- 7.5 months). Clinical risk profiles for atherosclerosis and medications were documented and patients were followed by their referring physicians under current "standard of care" guidelines. Carotid and aortic wall lumen areas were matched across the time-points from cross-sectional images.

RESULTS

The wall area increased by 8.67%, 10.64%, and 13.24% per year (carotid artery, thoracic aorta and abdominal aorta respectively, p < 0.001). The lumen area of the abdominal aorta increased by 4.97% per year (p = 0.002), but the carotid artery and thoracic aorta lumen areas did not change significantly. The use of statin therapy did not change the rate of increase of wall area of carotid artery, thoracic and abdominal aorta, but decreased the rate of change of lumen area of carotid artery (-3.08 +/- 11.34 vs. 0.19 +/- 12.91 p < 0.05).

CONCLUSIONS

Results of this study of multiple vascular beds indicated that different vascular locations exhibited varying progression of atherosclerosis and remodeling as monitored by CMR.

Associations between plasma C-reactive protein levels and the severities of coronary and aortic atherosclerosis

AIM

Limited correlations between C-reactive protein (CRP) and coronary artery disease (CAD) have been reported. Recently, MRI became a useful tool for non-invasively evaluating atherosclerotic plaques in thoracic and abdominal aortas.

METHODS

To elucidate the associations between plasma CRP levels and the severities of coronary and aortic atherosclerosis, we performed aortic black-blood MRI in 136 patients undergoing coronary angiography. For each patient, 9 slices of thoracic aorta and 9 slices of abdominal aorta were obtained at 12-mm intervals, and the plaque extent in each slice was scored. The degree of aortic atherosclerosis is represented as the sum of scores. The degree of coronary atherosclerosis is represented as the number of >50% stenotic vessels and >25% stenotic segments.

RESULTS

CAD (>50% stenosis) was present in 96 patients. Patients with CAD had higher CRP levels than those without CAD (median 0.78 vs. 0.48 mg/L, p<0.02). CRP levels tended to increase depending on the number of stenotic vessels: 0.48, 0.70, 0.74, and 0.88 mg/L (p=NS). CRP correlated weakly with the number of stenotic segments (r=0.21). Regarding aortic atherosclerosis, 136 patients were divided into quartiles by plaque score. CRP levels increased stepwise in quartiles: 0.40, 0.56, 1.08, and 1.10 mg/L (p<0.001). CRP levels also correlated with the plaque score (r=0.38). In multivariate analysis, aortic atherosclerosis was an independent factor for CRP levels, but coronary atherosclerosis was not.

CONCLUSION

Plasma CRP levels correlated with the severities of both coronary and aortic atherosclerosis, but CRP levels are more likely to reflect the severity of aortic atherosclerosis than coronary atherosclerosis.

Effect of lipid-lowering therapy with atorvastatin on atherosclerotic aortic plaques: a 2-year follow-up by noninvasive MRI

BACKGROUND

Using MRI, we reported plaque regression in thoracic aorta and retardation of plaque progression in abdominal aorta by 1-year atorvastatin. However, association between serial plaque changes and LDL-cholesterol levels was not fully elucidated.

DESIGN

A prospective, randomized, open-label trial.

METHODS

We investigated the long-term effect of 20 versus 5-mg atorvastatin on thoracic and abdominal plaques and the association between plaque progression and on-treatment LDL-cholesterol levels in 36 hypercholesterolemic patients. MRI was performed at baseline and 1 and 2 years of treatment. Vessel wall area change was evaluated.

RESULTS

The 20-mg dose markedly reduced LDL-cholesterol levels (-47%) versus 5-mg (-35%) dose. After 2 years of treatment, regression of thoracic plaques was found in the 20-mg group (-15% vessel wall area reduction), but not in the 5-mg group (+7%). Although the 20-mg dose induced plaque regression (-14%) from baseline to 1 year, no further regression was seen from 1 to 2 years of treatment (-1%). Regarding abdominal plaques, progression was found in the 5-mg group (+10%), but not in the 20-mg group (+2%). Plaque progression in the 5-mg group was found from baseline to 1 year (+8%), but not from 1 to 2 years (+2%). The degree of thoracic plaque regression correlated with LDL-cholesterol reduction (r = 0.61), whereas thoracic plaque change from 1 to 2 years correlated with on-treatment LDL-cholesterol levels (r = 0.64).

CONCLUSION

Twenty milligrams of atorvastatin regressed thoracic plaques. However, maintaining low LDL-cholesterol levels was needed to prevent plaque progression. In abdominal aorta, only retardation of plaque progression was found after 2 years of 20-mg treatment.

Aortic vessel wall magnetic resonance imaging at 3.0 Tesla: a reproducibility study of respiratory navigator gated free-breathing 3D black blood magnetic resonance imaging

The purpose of this study was to evaluate a free-breathing three-dimensional (3D) dual inversion-recovery (DIR) segmented k-space gradient-echo (turbo field echo [TFE]) imaging sequence at 3T for the quantification of aortic vessel wall dimensions. The effect of respiratory motion suppression on image quality was tested. Furthermore, the reproducibility of the aortic vessel wall measurements was investigated. Seven healthy subjects underwent 3D DIR TFE imaging of the aortic vessel wall with and without respiratory navigator. Subsequently, this sequence with respiratory navigator was performed twice in 10 healthy subjects to test its reproducibility. The signal-to-noise (SNR), contrast-to-noise ratio (CNR), vessel wall sharpness, and vessel wall volume (VWV) were assessed. Data were compared using the paired t-test, and the reproducibility of VWV measurements was evaluated using intraclass correlation coefficients (ICCs). SNR, CNR, and vessel wall sharpness were superior in scans performed with respiratory navigator compared to scans performed without. The ICCs concerning intraobserver, interobserver, and interscan reproducibility were excellent (0.99, 0.94, and 0.95, respectively). In conclusion, respiratory motion suppression substantially improves image quality of 3D DIR TFE imaging of the aortic vessel wall at 3T. Furthermore, this optimized technique with respiratory motion suppression enables assessment of aortic vessel wall dimensions with high reproducibility.

Assessment and reproducibility of aortic atherosclerosis magnetic resonance imaging: impact of 3-Tesla field strength and parallel imaging

OBJECTIVES

To investigate image quality and interstudy reproducibility of aortic atherosclerosis imaging at 1.5 T, and to explore the impact of parallel imaging techniques at 3 T.

MATERIALS AND METHODS

Institutional review board approval and informed consent were obtained. Thirty-two subjects (20 normal, 12 patients with impaired cardiac function) underwent 4 black-blood T2-weighted imaging studies of the abdominal aorta: 2 conventional studies at 1.5 T, a conventional study at 3 T, and an accelerated 3-T study with parallel imaging (SENSE). Contrast-to-noise ratio and image quality score (1-5 scale, 5 = highest quality) were determined for each study. Studies were analyzed for mean wall thickness and area plaque burden as endpoints for aortic atherosclerosis. Bland-Altman analyses were performed to determine interstudy reproducibility between imaging methods. Wilcoxon signed-rank tests were used to identify significant differences between methods (P < 0.05).

RESULTS

Image quality scores were comparable between 1.5 T and 3 T with SENSE (4.0 +/- 0.6 vs. 4.2 +/- 0.6, P = 0.21). Bland-Altman reproducibility for mean wall thickness was -0.03 mm +/- 0.15 (1.5 T vs. 1.5 T), 0.01 mm +/- 0.17 (1.5 T vs. 3 T without SENSE), and -0.01 mm +/- 0.18 (1.5 T vs. 3 T with SENSE), P = 0.83. Detection of the presence or absence of plaque was comparable. Bland-Altman reproducibility for area plaque burden was -0.02% +/- 0.32% (1.5 T vs. 1.5 T), 0.06% +/- 0.41% (1.5 T vs. 3 T without SENSE), and 0.11% +/- 0.33% (1.5 T vs. 3 T with SENSE), P = 0.41.

CONCLUSION

Black-blood MR imaging of aortic atherosclerosis is very reproducible. Parallel imaging at 3 T permits shorter scan time compared with conventional 1.5-T imaging with comparable measures of atherosclerosis extent.

Relation of aortic wall thickness and distensibility to cardiovascular risk factors (from the Multi-Ethnic Study of Atherosclerosis [MESA])

To determine the relation between aortic wall thickness (WT) and aortic distensibility (AD) with traditional cardiovascular risk factors in the Multi-Ethnic Study of Atherosclerosis (MESA) cohort, 1,053 participants in MESA who underwent cardiac magnetic resonance imaging were consecutively selected for the measurement of aortic WT and AD. Double inversion-recovery fast spin-echo images of the thoracic aorta were obtained to measure average and maximum WT. AD was measured at the same level using a gradient-echo cine sequence. Average and maximum WT were positively correlated with increasing age, and AD was inversely related to age (p <0.01). Compared with normotensive participants, those with hypertension had significantly greater mean average WT (2.45 vs 2.23 mm, p <0.01) and maximum WT (3.61 vs 3.41 mm, p <0.01) and lower AD (0.15 vs 0.2 mm Hg(-1), p <0.01). In multiple regression analysis, older age and hypertension were significantly associated with higher mean average WT, while older age, male gender, and higher blood pressure were associated with higher mean maximum WT. AD was inversely related to older age, hypertension, current smoking, African American ethnicity, and lower high-density lipoprotein cholesterol level. In conclusion, in the MESA cohort, older age and higher blood pressure were associated with higher aortic WT and lower AD. Decreased AD was further associated with current smoking, African American ethnicity, and higher high-density lipoprotein cholesterol level.

Aortic plaque imaging and monitoring atherosclerotic plaque interventions

The atherosclerotic process that results in coronary artery disease (CAD) is recognized to be a generalized process that may involve the entire vasculature. The association between CAD and atherosclerotic plaques in the thoracic aorta has often been reported using transesophageal echocardiography. An autopsy study showed plaques in the abdominal aorta, but not in the thoracic aorta, to be severe in patients with cardiac events. However, studies evaluating an association between abdominal aortic plaques and CAD are scarce. Recently, magnetic resonance imaging (MRI) has become a useful tool for the noninvasive evaluation of atherosclerotic plaques in both the thoracic and abdominal aortas. Plaques in the thoracic and abdominal aortas were found to be characteristically associated with hypercholesterolemia and smoking, respectively, suggesting different susceptibilities to risk factors. Because patients have various risk factors, it seems to be preferable to evaluate atherosclerosis in multiple vascular beds than in just 1 bed. Magnetic resonance imaging can evaluate atherosclerosis in multiple vascular beds in the same examination session. Complex aortic plaques, especially in the abdominal aorta, were found to be associated with myocardial infarction and complex coronary lesions, suggesting a link between aortic and coronary plaque instability. Aortic MRI may thus be useful for identifying vulnerable patients. Moreover, MRI is a powerful tool to serially evaluate plaque progression and regression. Intensive lipid-lowering therapy can regress aortic plaques, but the susceptibility to lipid lowering and the process of plaque regression may differ between the thoracic and abdominal aortic plaques.

Differential impact of age, sex, and hypertension on aortic atherosclerosis: the Framingham Heart Study

OBJECTIVE

The purpose of this study was to investigate the impact of age, sex, and hypertension (HTN) on aortic atherosclerotic burden using cardiovascular MRI (CMR) in a free-living longitudinally followed cohort.

METHODS AND RESULTS

1763 participants (829 M and 934 F; 38 to 88 years of age) of the Framingham Heart Study Offspring cohort underwent CMR of the thoracoabdominal aorta using an ECG-gated 2D T2-weighted black-blood sequence. Of these, 1726 subjects (96%) with interpretable CMR were characterized by sex, age-quartile, and presence or absence of HTN and clinical cardiovascular disease (CVD). Aortic plaque prevalence and volume increased with increasing age in both sexes. For the nonhypertensive (no-HTN) group, plaque was identified in 702 (46%) with greater prevalence in women than in men (P<0.006). HTN was associated with greater aortic plaque burden (P<0.02). The 200 subjects with clinical CVD had greater plaque burden than subjects without CVD (P<0.0001).

CONCLUSIONS

In this free-living longitudinally followed cohort, subclinical aortic atherosclerosis was seen in nearly half of subjects and increased with advancing age. HTN was associated with increased aortic plaque burden. Among no-HTN subjects, women had greater plaque burden than men. These data suggest that subclinical atherosclerosis is more common in no-HTN women and emphasize the importance of focusing on preventive measures in both sexes.

Does atherosclerotic aortic plaque detected by telecardiography indicate an increased risk of coronary artery disease?

OBJECTIVE

The purpose of this study was to determine the cause of aortic arch calcification and to evaluate its prognostic value as an indicator of cardiovascular disease and its severity.

METHODS AND RESULTS

The study was conducted prospectively among 1027 patients who underwent a coronary angiography in our hospital between April 2002 and September 2002 for suspected coronary artery disease. All chest x-rays were reviewed by a radiologist, who categorized aortic arch calcifications by their presence or absence. The patients were stratified according to age (< or =50, 51-64, and > or =65 years) to eliminate the influence of age on aortic arch calcification. Coronary lesions were considered either single-vessel or multivessel disease. Univariate analysis revealed significant correlation with age (r = 0.37; P < .001), presence of hypertension (r = 0.14; P < .001), smoking (r = -0.10; P = .001), presence of coronary artery disease (r = 0.10; P = .001), and the existence of multi-vessel disease (r = 0.09; P = .006). Multivariate analysis disclosed significant association with age and hypertension and no association with smoking, coronary artery disease, and other risk factors.

CONCLUSION

The aortic arch calcifications observed on plain chest x-rays are usually age related, and both aortic arch calcifications and coronary artery disease are strongly associated with age. The presence of aortic calcification on chest x-rays was not an indicator of the presence and extent of coronary artery disease.

Update on advances in atherothrombosis

The study of atherothrombosis is a rapidly evolving field, and significant progress was achieved in various aspects of the disease during the past year. In the area of diagnostic imaging, MRI and multidetector CT were actively used to evaluate the characteristics of the arterial wall, including calcified and noncalcified lesions, and both in the coronary and extracoronary vascular territories. There was also extensive research into the application of imaging modalities to visualize cellular or molecular disease processes, known as molecular imaging. Considerable efforts were devoted to the identification of novel biomarkers that reflect different components of atherothrombosis, namely inflammation, thrombogenicity, oxidative stress and reparative ability, predicting the presence of early disease or the risk of clinical events. In the therapeutic arena, substantial evidence accumulated on the beneficial effects of several pharmacologic agents, most significantly statins. Finally, important advances were also made in the understanding of the roles of immunity and neovascularization in atherogenesis, including the development and progression of disease at different stages. Awareness of these recent advances and new lines of active research is fundamental for health professionals involved in the care of patients with atherothrombosis. In this Review we present an overview of data in these areas.

Effect of bezafibrate therapy on atherosclerotic aortic plaques detected by MRI in dyslipidemic patients with hypertriglyceridemia

Fibrates reduce triglycerides (TG) and increase HDL-cholesterol levels, but there was no report showing plaque regression by fibrates. Using MRI, we investigated the effects of bezafibrate on aortic plaques in 22 dyslipidemic patients. All patients were asked to receive 400mg bezafibrate, but 8 who declined to have bezafibrate became the control group. Changes in vessel wall area (VWA) and lumen area (LA) from baseline to 1-year were evaluated. Bezafibrate reduced TG (-55%) and increased HDL-cholesterol levels (+29%). Bezafibrate reduced HDL size and increased LDL size. In thoracic plaques, bezafibrate reduced VWA (-6%, P<0.001) with no LA change, but VWA slightly progressed without bezafibrate (+5%). In abdominal plaques, bezafibrate reduced VWA (-8%, P<0.001) with LA increase (+3%, P<0.02), but VWA progressed without bezafibrate (+6%). VWA changes in thoracic and abdominal plaques correlated with TG reduction and HDL-cholesterol increase. Notably, VWA change in only abdominal plaques correlated with HDL size reduction and LDL size increase. Thus, bezafibrate induced plaque regression in thoracic and abdominal aortas with marked TG reduction and HDL-cholesterol increase, but the processes of plaque regression and vascular remodeling may differ between thoracic and abdominal aortas. However, because our study was not a controlled, randomized trial, further study is needed.

Subclinical coronary and aortic atherosclerosis detected by magnetic resonance imaging in type 1 diabetes with and without diabetic nephropathy

BACKGROUND

Patients with type 1 diabetes and nephropathy maintain an excess cardiovascular mortality compared with diabetic patients with normoalbuminuria. We sought to evaluate coronary and aortic atherosclerosis in a cohort of asymptomatic type 1 diabetic patients with and without diabetic nephropathy using cardiovascular magnetic resonance imaging.

METHODS AND RESULTS

In a cross-sectional study, 136 subjects with long-standing type 1 diabetes without symptoms or history of cardiovascular disease, including 63 patients (46%) with nephropathy and 73 patients with normoalbuminuria, underwent cardiovascular magnetic resonance imaging. All subjects underwent cardiac exercise testing and noninvasive tests for peripheral artery disease and autonomic neuropathy. Coronary artery stenoses were identified in 10% of subjects with nephropathy (versus 0% with normoalbuminuria; P=0.007). Coronary plaque burden, expressed as right coronary artery mean wall thickness (1.7+/-0.3 versus 1.3+/-0.2 mm; P<0.001) and maximum right coronary artery wall thickness (2.2+/-0.5 versus 1.6+/-0.3 mm; P<0.001), was greater in subjects with nephropathy. The prevalence of thoracic (3% versus 0%; P=0.28) and abdominal aortic plaque (22% versus 16%; P=0.7) was similar in both groups. Subjects with and without abdominal aortic plaques had similar coronary plaque burden.

CONCLUSIONS

In asymptomatic type 1 diabetes, cardiovascular magnetic resonance imaging reveals greater coronary plaque burden in subjects with nephropathy compared with those with normoalbuminuria.

Inflammation, obesity and cardiovascular function in African and Caucasian women from South Africa: the POWIRS study

The integrated relationship between inflammation, obesity and cardiovascular disease is currently a subject of much research interest. These specific relationships, however, have not been studied in-depth in South African population groups in order to determine the role of ethnicity. It is known that Africans, compared to Caucasians, suffer from a high prevalence of hypertension. It was therefore hypothesized that the levels of inflammatory markers (high-sensitivity C-reactive protein (hsCRP), fibrinogen and leptin) are higher in Africans compared to Caucasians and are notably associated with cardiovascular dysfunction in Africans. Apparently healthy African (N=102) and Caucasian (N=115) women, matched for age and body mass index (BMI), were recruited. Leptin, hsCRP, fibrinogen and lipid levels, waist circumference (WC), BMI, systolic and diastolic blood pressure, cardiac output (CO), total peripheral resistance (TPR) and Windkessel compliance were measured. Results showed that the levels of leptin, hsCRP and fibrinogen were significantly higher (P<0.05) in the African women. The inflammatory markers correlated strongly with cardiovascular parameters, age and obesity (BMI, WC) in both groups, but after adjusting for age and obesity, none of the correlations were significant anymore. Multiple regression analyses (with leptin, hsCRP or fibrinogen as dependent variable) showed that only leptin levels of African women were explained by cardiovascular parameters (BP, TPR and CO). In conclusion, even though African women had significantly higher leptin, hsCRP, fibrinogen and blood pressure levels than Caucasian women, no cardiovascular parameters explained the variation in the inflammatory markers (except for leptin levels of African women).

In Vivo Identification of Complicated Upper Thoracic Aorta and Arch Vessel Plaque by MR Direct Thrombus Imaging in Patients Investigated for Cerebrovascular Disease

OBJECTIVE

The objective of this article was to assess the feasibility of MR direct thrombus imaging (MRDTI) to evaluate the prevalence and location of complicated upper thoracic aortic and arch vessel plaque in patients referred for evaluation of cerebrovascular disease.

SUBJECTS AND METHODS

Patients referred for investigation of cerebrovascular disease by MRI were enrolled. Reasons for referral included transient ischemic attack/amaurosis fugax, acute infarct, remote infarct, or asymptomatic carotid disease. Of the 348 patients initially scanned, 17 were excluded from the analysis. The final patient population included 331 patients (199 men, 132 women; mean age, 67.7 years). Patients were scanned using MRDTI, a 3D, T1-weighted, fat-suppressed spoiled gradient echo that exploits the T1 shortening effects of methemoglobin, directly visualizing hemorrhage/thrombus in the vessel wall, thus identifying complicated plaque. Complicated plaque was defined as a high signal within the atherosclerotic plaque at least twice the signal intensity of muscle.

RESULTS

Forty-three of 331 patients (13%) had complicated upper thoracic aortic atherosclerotic disease, arch vessel atherosclerotic disease, or both. The upper thoracic aorta was involved in 36 of 43 patients (83.7%), and the left subclavian artery was involved in 14 of 43 patients (32.6%). Both the right subclavian artery and the brachiocephalic artery were involved in one of 43 patients (2.3%). Complicated carotid plaque was seen in 25 of 43 patients (58.1%).

CONCLUSION

MRDTI can be applied in the detection of complicated plaque in the upper thoracic aorta and arch vessels. Complicated plaque was identified in 13% of the patient population. The upper thoracic aorta was the most common site involved. This technique could be useful for the screening of asymptomatic at-risk patients.

Inflammation and atherosclerosis: novel insights into plaque formation and destabilization

BACKGROUND AND PURPOSE

The simplistic view of atherosclerosis as a disorder of pathological lipid deposition has been redefined by the more complex concept of an ongoing inflammatory response.

SUMMARY OF REVIEW

Apolipoprotein E and low-density lipoprotein (LDL)-receptor-deficient mice develop accelerated atherosclerosis allowing in-depth pathophysiological investigations. Atherosclerotic plaques in these mice contain large numbers of T cells and macrophages. Crossbreeding apolipoprotein E-deficient mice with T-cell-deficient mice and mice with impaired macrophage function (osteopetrotic op/op mice) disclosed the important impact of immune cells on atherosclerotic lesion development. In contrast to the detrimental role of T cells and macrophages, B cells appear to be atheroprotective. These basic experimental findings have partly been confirmed in studies of the human carotid artery system. Inflammation is not only instrumental in the development of human atheromatous plaques, but, importantly, plays a crucial role in the destabilization of internal carotid artery plaques, thus converting chronic atherosclerosis into an acute thrombo-embolic disorder. Humoral factors involved in internal carotid artery destabilization include cytokines, cyclooxygenase-2, matrix metalloproteinases, and tissue factor. Antibodies to oxidized LDL can reflect disease activity on one hand, but can also confer atheroprotection. Novel MRI techniques may aid in the in vivo assessment of acute plaque inflammation in humans.

CONCLUSIONS

The impact of inflammation on the development of atherosclerotic plaques and their destabilization opens new avenues for treatment. The effects of statins, acetylsalicyclic acid and angiotensin-converting enzyme inhibitors on stroke prevention may partly be attributable to their profound anti-inflammatory actions. Vaccination against modified LDL and heat shock proteins halt plaque progression in experimental atherosclerosis. Their potential for prevention of human atherosclerosis is currently under investigation.

Noninvasive imaging of atherosclerotic vessels by MRI for clinical assessment of the effectiveness of therapy

Atherosclerosis and its thrombotic complications are the major cause of morbidity and mortality in the industrialized countries. Despite advances in our understanding of the mechanisms of pathogenesis and new treatment modalities, the absence of an adequate noninvasive method for early detection limits prevention or treatment of patients with various degrees and localizations of atherothrombotic disease. The ideal clinical imaging modality for atherosclerosis should be safe, inexpensive, noninvasive or minimally invasive, accurate, and reproducible, thus allowing longitudinal studies in the same patients. Additionally, the results should correlate with the extent of atherosclerotic disease and have high predictive values for clinical events. In vivo, high-resolution magnetic resonance imaging (MRI) has recently emerged as one of the most promising techniques for the noninvasive study of atherothrombotic disease in several vascular beds such as the aorta, the carotid arteries, and the coronary arteries. Most importantly MRI can be used to characterize plaque composition as it allows the discrimination of lipid core, fibrosis, calcification, and intra-plaque hemorrhage deposits. MRI findings have been extensively validated against pathology in ex vivo studies of carotid, aortic, and coronary artery specimens obtained at autopsy and using experimental models of atherosclerosis. In vivo MRI of carotid arteries of patients referred for endarterectomy has shown a high correlation with pathology and with previous ex vivo results. A recent study in patients with plaques in the thoracic aorta showed that compared with transesophageal echocardiography plaque composition and size are more accurately characterized and measured using in vivo MRI. The composition of the plaque rather than the degree of stenosis determines the patient outcome. Therefore, a reliable noninvasive imaging tool able to detect early atherosclerotic disease in the various regions and identify the plaque composition is clinically desirable. MRI has potential in the detection arterial thrombi and in the definition of thrombus age. MRI has been used to monitor plaque progression and regression in several animal model of atherosclerosis and more recently in human. Advances in diagnosis prosper when they march hand-in-hand with advances in treatment. We stand at the threshold of accurate noninvasive assessment of atherosclerosis. Thus, MRI opens new strategies ranging from screening of high-risk patients for early detection and treatment as well as monitoring the target areas for pharmacological intervention.

A Possible Association Between Coronary Plaque Instability and Complex Plaques in Abdominal Aorta

OBJECTIVE

Coronary plaque instability causes myocardial infarction (MI). Angiographic lesions with such instability are complex lesions. Complex carotid plaques were reported to be prevalent in unstable angina. We investigated associations between coronary plaque instability, such as MI and angiographic complex coronary lesions, and aortic plaques.

METHODS AND RESULTS

Aortic MRI was performed in 146 patients undergoing coronary angiography, of whom 108 had coronary artery disease (CAD) and 44 also had MI. Prevalence of plaques in thoracic and abdominal aortas was higher in patients with than without CAD (73% and 94% versus 32% and 79%), but it was similar in CAD patients with and without MI. Notably, complex plaques in abdominal aorta were more prevalent in CAD patients with than without MI (36% versus 14%; P<0.025). In multivariate analysis, abdominal complex plaques were associated with MI (odds ratio [OR], 4.5; 95% CI, 1.5 to 13.8). Among patients without MI, thoracic and abdominal complex plaques were more prevalent in patients with than without complex coronary lesions (22% and 33% versus 2% and 7%; P<0.05). Abdominal complex plaques were also associated with complex coronary lesions (OR, 9.8; 95% CI, 1.1 to 85.9).

CONCLUSIONS

Complex plaques in abdominal aorta were associated with MI and complex coronary lesions, suggesting a link between coronary and aortic plaque instability.