B-mode ultrasound images of the carotid artery wall: correlation of ultrasound with histological measurements

Intima-media thickness at the near or far wall of the common carotid artery in cardiovascular risk assessment

Aims

Current guidelines recommend measuring carotid intima-media thickness (IMT) at the far wall of the common carotid artery (CCA). We aimed to precisely quantify associations of near vs. far wall CCA-IMT with the risk for atherosclerotic cardiovascular disease (CVD, defined as coronary heart disease or stroke) and their added predictive values.

Methods and results

We analysed individual records of 41 941 participants from 16 prospective studies in the Proof-ATHERO consortium {mean age 61 years [standard deviation (SD) = 11]; 53% female; 16% prior CVD}. Mean baseline values of near and far wall CCA-IMT were 0.83 (SD = 0.28) and 0.82 (SD = 0.27) mm, differed by a mean of 0.02 mm (95% limits of agreement: -0.40 to 0.43), and were moderately correlated [r = 0.44; 95% confidence interval (CI): 0.39-0.49). Over a median follow-up of 9.3 years, we recorded 10 423 CVD events. We pooled study-specific hazard ratios for CVD using random-effects meta-analysis. Near and far wall CCA-IMT values were approximately linearly associated with CVD risk. The respective hazard ratios per SD higher value were 1.18 (95% CI: 1.14-1.22; I² = 30.7%) and 1.20 (1.18-1.23; I² = 5.3%) when adjusted for age, sex, and prior CVD and 1.09 (1.07-1.12; I² = 8.4%) and 1.14 (1.12-1.16; I²=1.3%) upon multivariable adjustment (all P < 0.001). Assessing CCA-IMT at both walls provided a greater C-index improvement than assessing CCA-IMT at one wall only [+0.0046 vs. +0.0023 for near (P < 0.001), +0.0037 for far wall (P = 0.006)].

Conclusions

The associations of near and far wall CCA-IMT with incident CVD were positive, approximately linear, and similarly strong. Improvement in risk discrimination was highest when CCA-IMT was measured at both walls.

Obesity in adolescents associated with vascular aging - a study using ultra-high-resolution ultrasound

BACKGROUND

Obesity in adolescents is increasing worldwide and associated with an elevated cardiovascular risk later in life. In a group-comparative study, we investigated the association between adiposity in adolescents and signs of vascular aging and inflammation.

METHODS

Thirty-nine adolescents (10-18 years old), 19 with obesity and 20 with normal weight, were enrolled. The intima thickness and intima/media thickness ratio (I/M) were assessed using high-resolution ultrasound in the common carotid artery (center frequency 22 MHz) and the distal radial artery (RA; 50 MHz). Increased intima and high I/M are signs of vascular aging. Body characteristics, high-sensitivity C-reactive protein (hs-CRP), plasma lipids, and glycemic parameters were measured.

RESULTS

Adolescents with obesity, compared to normal-weight peers, had elevated plasma lipid, insulin c-peptide, and hs-CRP levels, the latter increasing exponentially with increasing adiposity. Obese adolescents had a thicker RA intima layer [0.005 mm; 95% confidence intervals (0.000, 0.009); P = 0.043] and a higher RA I/M [0.10; (0.040, 0.147); P < 0.0007]. Group differences for the RA I/M remained significant after adjustment for age, sex, fasting plasma insulin, and body mass index, both separately and together (P = 0.032). The RA I/M was correlated with hs-CRP, and both were correlated with the analyzed cardiovascular risk factors. Receiver operating curve c-values for RA I/M (0.86) and hs-CRP (0.90) strongly indicated correct placement in the obese or non-obese group.

CONCLUSIONS

Adolescents with obesity had significantly more extensive vascular aging in the muscular RA, than normal-weight peers. The findings support an inflammatory link between obesity and vascular aging in adolescents.

Comparison of histological and computed tomographic measurements of pig lung bronchi

Aim

Light microscopy is used as template in the evaluation and further development of medical imaging methods. Tissue shrinkage caused by histological processing is known to influence lung tissue dimensions. In diagnosis of COPD, computed tomography (CT) is widely used for automated airway measurement. The aim of this study was to compare histological and computed tomographic measurements of pig lung bronchi.

Methods

Airway measurements of pig lungs were performed after freezing under controlled inflation pressure in a liquid nitrogen bath. The wall thickness of seven bronchi was measured via Micro-CT and CT using the integral-based method (IBM) and the full-width-at-half-maximum method (FWHM) automatically and histologically on frozen and paraffin sections. Statistical analysis was performed using the Wilcoxon test, Pearson's correlation coefficient with a significance level at p<0.05, scatter plots and Bland–Altman plots.

Results

Bronchial wall thickness was smallest in frozen sections (median 0.71 mm) followed by paraffin sections (median 0.75 mm), Micro-CT (median 0.84 mm), and CT measurements using IBM (median 0.68 mm) and FWHM (median 1.69 mm). Statistically significant differences were found among all tested groups (p<0.05) except for CT IBM and paraffin and frozen sections and Micro-CT. There was high correlation between all parameters with statistical significance (p<0.05).

Conclusions

Significant differences in airway measurement were found among the different methods. The absolute measurements with CT IBM were closest to the histological results followed by Micro-CT, whereas CT FWHM demonstrated a distinct divergence from the other groups.

Automated measurement techniques advance diagnosis of lung diseases. Pig bronchi wall size varies between Micro-CT, CT IBM, CT FWHM and histology. CT IBM is closest to histological results, followed by Micro-CT. CT FWHM differs highly from all other groups.https://bit.ly/3iRXSrv

The Association of Self-Reported Muscle-Strengthening Activities With Carotid Intima-Media Thickness in Older Adults: Cooper Center Longitudinal Study

The purpose of the current investigation was to examine the cross-sectional associations of participation in muscle-strengthening activities (MSAs) with carotid intima-media thickness (CIMT) among older adults. The data are from 2,557 older adult participants enrolled in an observational cohort who reported no history of cardiovascular disease. MSA was determined using a questionnaire. Carotid ultrasound was performed to measure the CIMT of the common carotid artery bilaterally. Logistic regression models were constructed to estimate the association of MSA with CIMT after adjustment for potential confounders. The participants were aged 68.6 ± 7.0 years, and the majority were male (71.7%) and White (96.5%); 18% had abnormal CIMT. Meeting the physical activity guidelines for MSA was inversely associated with abnormal CIMT after adjustment for age and sex. However, this observed inverse relation became statistically null after further adjustment for cardiovascular disease risk factors, including aerobic physical activity.

The Association of Physical Activity With Carotid Intima Media Thickening in a Healthy Older Population: Cooper Center Longitudinal Study

The purpose of this study was to examine the association between self-reported physical activity (PA) and mean common carotid artery intima-media thickness (CCA IMT) among older adults. The data are from 1,811 Cooper Center Longitudinal Study participants, who were aged ≥60 years, with no history of cardiovascular disease. A medical history questionnaire was used to assess PA. Carotid ultrasound was performed to measure CCA IMT and the presence of plaque and stenosis. Logistic regression models were constructed to estimate the association between PA and CCA IMT after adjustment for covariates. The participants were aged 69.2 ± 5.9 years, and the majority were male (73.3%) and White (96.7%). The odds ratio of abnormal thickening of CCA IMT was 0.72 (95% confidence interval [0.54, 0.96]) in physically active participants (≥500 metabolic equivalent·min/week) after adjustment for covariates. In the current study, meeting PA guidelines in older adulthood was associated with lower odds of abnormal thickening of CCA IMT.

Quantitative evaluation of carotid atherosclerotic vulnerable plaques using in vivo T1 mapping cardiovascular magnetic resonaonce: validation by histology

BACKGROUND

It has been proved that multi-contrast cardiovascular magnetic resonance (CMR) vessel wall imaging could be used to characterize carotid vulnerable plaque components according to the signal intensity on different contrast images. The signal intensity of plaque components is mainly dependent on the values of T1 and T2 relaxation. T1 mapping recently showed a potential in identifying plaque components but it is not well validated by histology. This study aimed to validate the usefulness of in vivo T1 mapping in assessing carotid vulnerable plaque components by histology.

METHODS

Thirty-four subjects (mean age, 64.0 ± 8.9 years; 26 males) with carotid plaques referred to carotid endarterectomy were prospectively enrolled and underwent 3 T CMR imaging from May 2017 to October 2017. The T1 values of intraplaque hemorrhage (IPH), necrotic core (NC) and loose matrix (LM) which were identified on multi-contrast vessel wall images or histology were measured on in-vivo T1 mapping. The IPHs were divided into two types based on the proportion of the area of fresh hemorrhage on histology. The T1 values of different plaque components were compared using Mann-Whitney U test and the agreement between T1 mapping and histology in identifying and quantifying IPH was analyzed with Cohen's Kappa and intraclass correlation coefficient (ICC).

RESULTS

Of 34 subjects, 19 had histological specimens matched with CMR imaging. The mean T1 values of IPH (651 ± 253 ms), NC (1161 ± 182 ms) and LM (1447 ± 310 ms) identified by histology were significantly different. The T1 values of Type 1 IPH were significantly shorter than that of Type 2 IPH (456 ± 193 ms vs. 775 ± 205 ms, p < 0.001). Moderate to excellent agreement was found in identification (kappa = 0.51, p < 0.001), classification (kappa = 0.40, p = 0.028) and segmentation (ICC = 0.816, 95% CI 0.679-0.894) of IPHs between T1 mapping and histology.

CONCLUSIONS

The T1 values of carotid plaque components, particularly for intraplaque hemorrhage, are differentiable, and the stage of intraplaque hemorrhage can be classified according to T1 values, suggesting the potential capability of assessment of vulnerable plaque components by T1 mapping.

Quantitative assessment of carotid artery atherosclerosis by three-dimensional magnetic resonance and two-dimensional ultrasound imaging: a comparison study

Background

It has been proven that magnetic resonance (MR) and ultrasound imaging are useful tools in the quantification of carotid atherosclerotic plaques. However, there are only a few pieces of evidence to illustrate the links of quantitative measurements of carotid plaques between MR and ultrasound imaging. This study looked to compare the quantitative measurements of carotid plaques and investigate their relationship between three-dimensional (3D) MR vessel wall imaging and two-dimensional (2D) ultrasound imaging.

Methods

Seventy-five asymptomatic elderly subjects (mean age: 73.3±5.7 years; 45 males) with carotid atherosclerotic plaques diagnosed by both ultrasound and MR imaging were included in this study. The plaque size, including the maximum wall thickness (Max WT), plaque length, and plaque area, was measured by 3D MR and ultrasound imaging on longitudinal and cross-sectional views. The quantitative assessments of carotid plaque size were compared and correlated between 3D MR and 2D ultrasound imaging.

Results

In total, the quantitative measurements of 101 plaques on longitudinal views or 44 plaques on cross-sectional views of both MR and ultrasound imaging were compared. The Max WT of the plaques (longitudinal: 2.9±0.8 vs. 2.4±0.9 mm; cross-sectional: 3.2±1.1 vs. 2.6±0.7 mm) and plaque areas (longitudinal: 24.3±13.4 vs. 17.0±12.7 mm²; cross-sectional: 24.9±24.6 vs. 16.8±13.3 mm²) measured by MR imaging were found to be significantly higher than those measured by ultrasound imaging (all P<0.001). Moderate to strong correlations were found in Max WT, plaque area, plaque length between 3D MR and ultrasound imaging.

Conclusions

The quantitative measurements of carotid plaques using 3D MR and 2D ultrasound are significantly correlated. The plaque area and Max WT measured by 3D MR imaging are more significant than these parameters measured by 2D ultrasound imaging, which might be explained by the resolution of MR imaging and the workflow of measurements.

Global perspective on carotid intima-media thickness and plaque: should the current measurement guidelines be revisited?

Carotid intima-media thickness (cIMT) and carotid plaque (CP) currently act as risk predictors for CVD/Stroke risk assessment. Over 2000 articles have been published that cover either use cIMT/CP or alterations of cIMT/CP and additional image-based phenotypes to associate cIMT related markers with CVD/Stroke risk. These articles have shown variable results, which likely reflect a lack of standardization in the tools for measurement, risk stratification, and risk assessment. Guidelines for cIMT/CP measurement are influenced by major factors like the atherosclerosis disease itself, conventional risk factors, 10-year measurement tools, types of CVD/Stroke risk calculators, incomplete validation of measurement tools, and the fast pace of computer technology advancements. This review discusses the following major points: 1) the American Society of Echocardiography and Mannheim guidelines for cIMT/CP measurements; 2) forces that influence the guidelines; and 3) calculators for risk stratification and assessment under the influence of advanced intelligence methods. The review also presents the knowledge-based learning strategies such as machine and deep learning which may play a future role in CVD/stroke risk assessment. We conclude that both machine learning and non-machine learning strategies will flourish for current and 10-year CVD/Stroke risk prediction as long as they integrate image-based phenotypes with conventional risk factors.

A Special Report on Changing Trends in Preventive Stroke/Cardiovascular Risk Assessment Via B-Mode Ultrasonography

PURPOSE OF REVIEW

Cardiovascular disease (CVD) and stroke risk assessment have been largely based on the success of traditional statistically derived risk calculators such as Pooled Cohort Risk Score or Framingham Risk Score. However, over the last decade, automated computational paradigms such as machine learning (ML) and deep learning (DL) techniques have penetrated into a variety of medical domains including CVD/stroke risk assessment. This review is mainly focused on the changing trends in CVD/stroke risk assessment and its stratification from statistical-based models to ML-based paradigms using non-invasive carotid ultrasonography.

RECENT FINDINGS

In this review, ML-based strategies are categorized into two types: non-image (or conventional ML-based) and image-based (or integrated ML-based). The success of conventional (non-image-based) ML-based algorithms lies in the different data-driven patterns or features which are used to train the ML systems. Typically these features are the patients' demographics, serum biomarkers, and multiple clinical parameters. The integrated (image-based) ML-based algorithms integrate the features derived from the ultrasound scans of the arterial walls (such as morphological measurements) with conventional risk factors in ML frameworks. Even though the review covers ML-based system designs for carotid and coronary ultrasonography, the main focus of the review is on CVD/stroke risk scores based on carotid ultrasound. There are two key conclusions from this review: (i) fusion of image-based features with conventional cardiovascular risk factors can lead to more accurate CVD/stroke risk stratification; (ii) the ability to handle multiple sources of information in big data framework using artificial intelligence-based paradigms (such as ML and DL) is likely to be the future in preventive CVD/stroke risk assessment.

The association of midlife cardiorespiratory fitness with later life carotid atherosclerosis: Cooper Center Longitudinal Study

BACKGROUND AND AIMS

While numerous cross-sectional studies have demonstrated an inverse relationship between cardiorespiratory fitness (CRF) and carotid atherosclerosis in middle age, much less is known about the association of midlife CRF with carotid atherosclerosis in later life.

METHODS

We studied 1094 participants, free of cardiovascular disease, who completed a maximal exercise test (GXT) for an objective measure of CRF between ages 40 and 59 and carotid ultrasound after the age of 59, with at least five years between studies. Carotid intima media thickness was measured. Assessments were also made regarding the presence of plaque and percent stenosis in four regions: common carotid, bulb, internal carotid and external carotid arteries. Multivariable logistic regression models were constructed to estimate the association of CRF with carotid artery disease.

RESULTS

At the time of GXT and carotid scan, participants were aged 50.7 ± 5.7 years and 69.3 ± 6.4 years, respectively. Almost half of participants had high midlife CRF (48.6%); 41.3% and 10.1% had moderate and low CRF, respectively. Over a mean follow-up period of 18.6 ± 8.5 years, the odds of having carotid artery disease in later life in the high CRF group was 0.50 (95% CI: 0.29-0.87) compared with the low CRF group. Each 1 MET increase in CRF was associated with 10% lower odds of having carotid artery disease (OR = 0.89, 95% CI: 0.80-0.98).

CONCLUSIONS

Midlife CRF was inversely associated with carotid artery disease measured almost two decades later. This may represent a mechanistic link between high midlife CRF and reduced risk of stroke in later life.

Should We Ignore What We Cannot Measure? How Non-Uniform Stretch, Non-Uniform Wall Thickness and Minor Side Branches Affect Computational Aortic Biomechanics in Mice

In order to advance the state-of-the-art in computational aortic biomechanics, we investigated the influence of (i) a non-uniform wall thickness, (ii) minor aortic side branches and (iii) a non-uniform axial stretch distribution on the location of predicted hotspots of principal strain in a mouse model for dissecting aneurysms. After 3 days of angiotensin II infusion, a murine abdominal aorta was scanned in vivo with contrast-enhanced micro-CT. The animal was subsequently sacrificed and its aorta was scanned ex vivo with phase-contrast X-ray tomographic microscopy (PCXTM). An automatic morphing framework was developed to map the non-pressurized, non-stretched PCXTM geometry onto the pressurized, stretched micro-CT geometry. The output of the morphing model was a structural FEM simulation where the output strain distribution represents an estimation of the wall deformation, not only due to the pressurization, but also due to the local axial stretch field. The morphing model also included minor branches and a mouse-specific wall thickness. A sensitivity study was then performed to assess the influence of each of these novel features on the outcome of the simulations. The results were supported by comparing the computed hotspots of principal strain to hotspots of early vascular damage as detected on PCXTM. Non-uniform axial stretch, non-uniform wall thickness and minor subcostal arteries significantly alter the locations of calculated hotspots of maximal principal strain. Even if experimental data on these features are often not available in clinical practice, one should be aware of the important implications that simplifications in the model might have on the final simulated result.

Carotid Intima-media Thickness Measurements: Relations with Atherosclerosis, Risk of Cardiovascular Disease and Application in Randomized Controlled Trials

Advances in the field of carotid ultrasound have been incremental, resulting in a steady decrease in measurement variability. Improvements in edge detection algorithms point toward increasing automation of CIMT measurements. The major advantage of CIMT is that it is completely noninvasive and can be repeated as often as required. It provides a continuous measure since all subjects have a measurable carotid wall. It is also relatively inexpensive to perform, and the technology is widely available. A graded relation between raising LDL cholesterol and increased CIMT is apparent. Increased CIMT has been shown consistently to relate the atherosclerotic abnormalities elsewhere in the arterial system. Moreover, increased CIMT predicts future vascular events in both populations from Caucasian ancestry and those from Asian ancestry. Furthermore, lipid‑lowering therapy has been shown to affect CIMT progression within 12–18 months in properly designed trials with results congruent with clinical events trials. In conclusion, when one wants to evaluate the effect of a pharmaceutical intervention that is to be expected to beneficially affect atherosclerosis progression and to reduce CV event risk, the use of CIMT measurements over time is a valid, suitable, and evidence‑based choice.

Ex vivo thickness measurement of cartilage covering the temporomandibular joint

Articular cartilage covers the temporomandibular joint (TMJ) and provides smooth and nearly frictionless articulation while distributing mechanical loads to the subchondral bone. The thickness of the cartilage is considered to be an indicator of the stage of development, maturation, aging, loading history, and disease. The aim of our study was to develop a method for ex vivo assessment of the thickness of the cartilage that covers the TMJ and to compare that with two other existing methods. Eight porcine TMJ condyles were used to measure cartilage thickness. Three different methods were employed: needle penetration, micro-computed tomography (micro-CT), and histology; the latter was considered the gold standard. Histology and micro-CT scanning results showed no significant differences between thicknesses throughout the condyle. Needle penetration produced significantly higher values than histology, in the lateral and anterior regions. All three methods showed the anterior region to be thinner than the other regions. We concluded that overestimated thickness by the needle penetration is caused by the penetration of the needle through the first layer of subchondral bone, in which mineralization is less than in deeper layers. Micro-CT scanning method was found to be a valid method to quantify the thickness of the cartilage, and has the advantage of being non-destructive.

Sonographic Evaluation of the Carotid Intima-media Complex Thickness in Nigerian Chronic Kidney Disease Patients

Atherosclerotic cardiovascular disease is the leading cause of mortality in patients with chronic kidney disease (CKD). Measurement of the carotid artery intima-media thickness (CIMT) is being used by many investigators to detect an increased risk of coronary artery atherosclerotic disease and document treatment effects. This study compares CIMT measurements in 75 patients with chronic kidney disease to a matched cohort of 75 subjects with normal kidney function. In plaque-free arterial segments, the CIMT was measured manually in the longitudinal plane from the far walls of a segment of the common carotid artery 3 cm in length adjacent to the carotid bifurcation. Patients with CKD had a significantly higher mean CIMT compared to those with normal renal function (0.86 ± 0.42 mm vs 0.69 ± 0.21 mm; P < .01). Mean CIMT values did not differ significantly between patients with different stages of CKD (stage 3: 0.88 ± 0.14 mm; stage 4: 0.89 ± 0.18 mm; and stage 5: 0.87 ± 0.14 mm, P = .94). These data indicate that CIMT is significantly higher in patients with CKD compared with controls, regardless of the stage of their disease, and may be a readily available noninvasive means of further assessing cardiovascular risk in CKD patients.

Extravascular optical coherence tomography: evaluation of carotid atherosclerosis and pravastatin therapy

BACKGROUND AND PURPOSE

Extravascular optical coherence tomography (OCT), as a noninvasive imaging methodology with micrometer resolution, was evaluated in a murine model of carotid atherosclerosis by way of assessing the efficacy of pravastatin therapy.

METHODS

An OCT device was engineered for extravascular plaque imaging. Wild-type mice and apolipoprotein E-deficient (ApoE(-/-)) mice were randomized to 3 treatment groups: (1) wild-type on a diet of standard rodent chow (n=13); (2) ApoE(-/-) on a high-fat, atherosclerotic diet (HFD; n=13); and (3) ApoE(-/-) on a HFD given daily pravastatin (n=13). Mice were anesthetized and the left common carotid was surgically exposed. Three-dimensional (3D; 2 spatial dimensions+time) and 4D (3 spatial dimensions+time) OCT images of the vessel lumen patency were evaluated. After perfusion, in situ OCT imaging was performed for statistical comparison with the in vivo results and final histology.

RESULTS

Intraoperative OCT imaging positively identified carotid plaque in 100% of ApoE(-/-) mice on HFD. ApoE(-/-) mice on HFD had a significantly decreased lumen patency when compared with that in wild-type mice (P<0.001). Pravastatin therapy was found to increase lumen patency significantly in ApoE(-/-) mice on HFD (P<0.01; compared with ApoE(-/-) on HFD). The findings were confirmed with OCT imaging after perfusion and histology.

CONCLUSIONS

OCT imaging offers the potential for real-time, detailed vessel lumen evaluation, potentially improving surgical accuracy and outcomes during cerebrovascular neurosurgical procedures. Pravastatin significantly increases vessel lumen patency in the ApoE(-/-) mouse on HFD.

Low wall stress in the popliteal artery: Other mechanisms responsible for the predilection of aneurysmal dilatation?

The popliteal artery (PA) is, after aorta, the most common site for aneurysm formation. Why the PA is more susceptible than other peripheral muscular arteries is unknown. We hypothesized that the wall composition, which in turn affects wall properties, as well as the circumferential wall stress (WS) imposed on the arterial wall, might differ compared to other muscular arteries. The aim was to study the WS of the PA in healthy subjects with the adjacent, muscular, common femoral artery (CFA) as a comparison. Ninety-four healthy subjects were included in this study (45 males, aged 10-78 years and 49 females, aged 10-83 years). The diameter and intima-media thickness (IMT) in the PA and CFA were investigated with ultrasound. Together with blood pressure the WS was defined according to the law of Laplace adjusted for IMT. The diameter increased with age in both PA and CFA (p<0.001), with males having a larger diameter than females (p<0.001). IMT increased with age in both PA and CFA (p<0.001), with higher IMT values in males only in PA (p<0.001). The calculated WS was unchanged with age in both arteries, but lower in PA than in CFA in both sexes (p<0.001). In conclusion, this study shows that the PA and CFA WS is maintained during aging, probably due to a compensatory remodelling response with an increase in arterial wall thickness. However, the stress imposed on the PA wall is quite low, indicating that mechanisms other than WS contribute to the process of pathological arterial dilatation in the PA.

Carotid artery intima-media thickness and the renin-angiotensin system

Carotid artery intima-media thickness (IMT) is a biomarker for cardiovascular disease that also predicts the risk of cardiovascular mortality. Angiotensin-converting enzyme (ACE) inhibition is a unique therapeutic modality because it both treats hypertension and improves arterial health and cardiovascular disease outcomes. Controversy exists regarding the role of ACE inhibitors and angiotensin receptor blockers (ARBs) in IMT regression. Our article provides an update on how ACE inhibitors and ARBs could play a role in decreasing IMT.

Prevalence and severity of atherosclerosis in different arterial territories and its relation with obesity

BACKGROUND

There is uneven association between obesity, traditional risk factors, and cardiovascular events. We aimed to analyze the relation between cardiovascular risk factors, including obesity, with the severity of atherosclerosis in different arterial territories.

METHODS

Arteries from five territories (circle of Willis, carotids, coronaries, aorta, and renal) were taken from 185 persons, newborn to 90 years undergoing autopsy in the Forensic Medical Service in Mexico City, to determine atherosclerotic lesions by histopathological study. Lesions were classified according to the American Heart Association grading system as early (types I-III) and advanced (types IV-VI). The degree of atherosclerosis was correlated with arterial territories and risk factors.

RESULTS

Frequencies of advanced lesions according to arterial territories were as follows: circle of Willis, 28%; right carotid, 36%; left carotid, 25%; right coronary, 71%; left coronary, 85%; right renal, 26%; left renal, 29%; and aorta, 52%; P=.0001, for all analyses. There was a higher risk for advanced lesions with increasing body mass index (BMI) (P=.004). However, after adjusting for age, gender, smoking status, hypertension, and diabetes mellitus, BMI was not independently associated with advanced lesions.

CONCLUSIONS

Coronary arteries are significantly more affected than other arterial territories regardless of risk factors, showing the effect of local and systemic factors in the severity of atherosclerosis. We did not find an independent association between advanced atherosclerotic lesions and obesity.

Carotid intima-media thickness studies: study design and data analysis

BACKGROUND

Carotid intima-media thickness (CIMT) measurements have been widely used as primary endpoint in studies into the effects of new interventions as alternative for cardiovascular morbidity and mortality. There are no accepted standards on the use of CIMT measurements in intervention studies and choices in the design and analysis of a CIMT study are generally based on experience and expert opinion. In the present review, we provide an overview of the current evidence on several aspects in the design and analysis of a CIMT study on the early effects of new interventions.

SUMMARY OF ISSUES

A balanced evaluation of the carotid segments, carotid walls, and image view to be used as CIMT study endpoint; the reading method (manual or semi-automated and continuously or in batch) to be employed, the required sample size, and the frequency of ultrasound examinations is provided. We also discuss the preferred methods to analyse longitudinal CIMT data and address the possible impact of, and methods to deal with missing and biologically implausible CIMT values.

CONCLUSIONS

Linear mixed effects models are the preferred way to analyse CIMT data and do appropriately handle missing and biologically implausible CIMT values. Furthermore, we recommend to use extensive CIMT designs that measure CIMT at regular points during the multiple carotid sites as such approach is likely to increase the success rates of CIMT intervention studies designed to evaluate the effects of new interventions on atherosclerotic burden.

Novel associations for coronary artery disease derived from genome wide association studies are not associated with increased carotid intima-media thickness, suggesting they do not act via early atherosclerosis or vessel remodeling

BACKGROUND

Recent genome-wide association studies (GWAS) have identified associations with myocardial infarction and coronary artery disease (CAD), but the mechanisms underlying these associations remain largely unclear. Carotid intima-media thickness (IMT) is a measure of early arterial remodeling and arteriosclerosis. Therefore, if CAD associated SNPs are also associated with carotid IMT; it suggests that they are acting via the early stages of the atherosclerotic process.

METHODS

In three large community based independent populations (CAPS, KORA and Young Finns) of European ancestry in which common carotid IMT had been measured (total 4961 individuals), we determined whether SNPs that have been associated with CAD in GWAS studies are also associated with carotid IMT. Associations with plaque were not examined.

RESULTS

We identified 11 SNPs and one haplotype previously associated with CAD. None of these were associated with common carotid IMT.

CONCLUSIONS

We found no evidence that SNPs associated with CAD on GWAS are also associated with carotid IMT. This suggests these genetic associations are not acting via early vessel remodeling or early arteriosclerosis.

Carotid intima–media thickness: a suitable alternative for cardiovascular risk as outcome?

BACKGROUND

Surrogate markers for cardiovascular disease might be of great value in observational research, clinical trials, and clinical practice. Carotid intima-media thickness (CIMT) is probably the most commonly used marker for atherosclerotic disease as an alternative for cardiovascular morbidity and mortality. A suitable marker for atherosclerosis, however, should meet several criteria before it can be validly used.

METHODS AND RESULTS

We reviewed the literature following a set of criteria for a surrogate marker. These include a comparison with a 'gold standard'; adequate reproducibility; cross-sectional relations with established risk factors and prevalent disease; relations with severity of atherosclerosis elsewhere in the arterial system; relations with the occurrence with future events; ability for a biomarker to change over time; ability to be affected by interventions over time; and relations between change over time in biomarker level and change in risk. A large number of studies from a variety of populations provide evidence for the validity of CIMT as a suitable measure of atherosclerotic disease. Data on the relation between change in CIMT and change in risk, however, is much sparser.

CONCLUSION

CIMT progression meets the criteria of a surrogate for cardiovascular disease endpoints and may be considered as a valid alternative for cardiovascular events as outcome. Further studies should examine the association between changes in CIMT and changes in risk for future events.

Carotid intima-media thickness as a surrogate marker of cardiovascular disease in diabetes

BACKGROUND

Diabetes mellitus is associated with a high risk of cardiovascular disease. Carotid intima-media thickness (CIMT) is increasingly used as a surrogate marker for atherosclerosis. Its use relies on its ability to predict future clinical cardiovascular end points.

METHODS

This review examines the evidence linking CIMT as a surrogate marker of vascular complications in people with type 1 and type 2 diabetes. We have also reviewed the various treatment strategies which have been shown to influence CIMT.

CONCLUSIONS

CIMT measurement is an effective, noninvasive tool which can assist in identifying people with diabetes who are at higher risk of developing microvascular and macrovascular complications. It may also help to evaluate the effectiveness of various treatment strategies used to treat people with diabetes.

New advances in noninvasive imaging of the carotid artery: CIMT, contrast-enhanced ultrasound, and vasa vasorum

Carotid ultrasound measurement of carotid intima-media thickness (CIMT) and detection of plaques is a useful method to better assess cardiovascular disease risk status, especially in those at intermediate risk. We discuss the use CIMT and other emerging techniques such as contrast-enhanced carotid ultrasound imaging in the evaluation of the carotid artery and its value in cardiovascular disease.

Associations between carotid artery wall thickness and cardiovascular risk factors using multidetector CT

BACKGROUND AND PURPOSE

It has been demonstrated that the increase in CAWT is associated with an increased risk of stroke and its severity. The aim of this study was to determine whether CAWT evaluated by MDCTA is associated with the following cardiovascular risk factors: hypertension, diabetes mellitus, dyslipidemia, and smoking.

MATERIALS AND METHODS

This was a retrospective study. One hundred sixty-eight patients (120 men; mean age, 68.96 years ± 11.2 years SD) were analyzed by using a multidetector row CT scanner. In each patient, CAWT was measured by using an internal digital caliper. Continuous data were described as the mean value ± SD and were compared by using the Student t test. We performed simple logistic regressions to evaluate the association between CAWT and the following: hypertension, diabetes mellitus, dyslipidemia, and smoking. A P value < .05 indicated statistical significance.

RESULTS

The distal common CAWT varied from 0.5 to 1.5 mm. We observed that hypertension and diabetes mellitus were associated with increased (>1 mm) CAWT (P = .0041 and P = .0172, respectively). There was no significant association between increased CAWT and dyslipidemia or smoking.

CONCLUSIONS

In our selected group, the results of this work show that an increased CAWT is associated with the cardiovascular risk determinants hypertension and diabetes. Further studies are necessary to evaluate whether it is possible to apply our observations to the general population.

Relation of common carotid intima-media thickness with left ventricular mass caused by shared risk factors for hypertrophy

BACKGROUND

It is unclear whether the relationship between common carotid intima-media thickness (cCIMT) and left ventricular mass (LVM) is due to shared risk factors for atherosclerosis or for hypertrophy.

METHODS

In 525 hypertensive subjects at high cardiovascular risk, the relation of cCIMT to LVM and established vascular risk factors was studied.

RESULTS

CCIMT was positively related to LVM. In a multivariable model including age, gender, height, weight, and LVM, a 1-g increase in LVM related to an increase in cCIMT of 1.6 microm (95% confidence interval, 0.8-2.4). After adjustment for atherosclerotic risk factors, notably previous stroke or transient ischemic attack, peripheral arterial disease, lipid-lowering medication, albuminuria and current smoking, the relation remained unchanged. In contrast, addition of systolic and diastolic blood pressure and hypertension treatment attenuated Beta for the relation between cCIMT and LVM with 19% to 1.3 microm (95% confidence interval, 0.2-2.2).

CONCLUSION

The relationship between cCIMT and LVM may be due to risk factors for hypertrophy rather than for atherosclerotic factors in a considerable proportion of patients.

Magnetic resonance of carotid artery ageing in healthy subjects

OBJECTIVE

To assess how the arterial wall of the carotid artery changes with age in normal subjects by cardiovascular magnetic resonance (CMR).

METHODS

Carotid CMR was performed in 100 normal subjects (10 per sex per decade) who were free of atherosclerotic risk factors and carotid atherosclerosis. Using three-dimensional computer modeling, the volumes of the arterial wall, lumen, and the total vessel were calculated, and the wall/outer wall (W/OW) ratio was derived.

RESULTS

Wall volume and total vessel volume increased significantly with age in both sexes (p<0.006), and this was more marked in males. The W/OW ratio also increased significantly with age (p<0.001). Lumen volume increased significantly with age in males (p<0.001), but not in females (p=0.1).

CONCLUSIONS

In normal subjects, carotid wall volume increases with age. In men, this vessel wall volume increase is associated with significant remodeling of the lumen and outer wall. These data relating normal carotid findings with ageing are important for further CMR studies of early atherosclerosis.

Carotid intima-media thickness measurements: techniques and clinical relevance

Atherosclerosis is a systemic disease that is responsible for most cardiovascular events and stroke. Epidemiologic studies and intervention trials based on the incidence of acute vascular disease end points require years of follow-up, the participation of large populations, or both. As a consequence, such studies consume considerable time and financial resources. The use of surrogate markers, therefore, is of paramount relevance because it allows researchers to have reliable data in less time and from reduced populations. Intima-media thickness (IMT) measured by B-mode ultrasound is the most studied surrogate marker and has been validated by official medical agencies. In this article, we review the most important technical considerations related to its measurement and highlight issues that should be systematically addressed in IMT-related studies. In summary, the use of IMT as an end point in clinical studies is of great value, but several technical limitations might jeopardize its interpretation.

Reduced aortic wall stress in diabetes mellitus

OBJECTIVE

Most risk factors are similar for abdominal aortic aneurysm (AAA) and atherosclerosis, e.g. smoking, male gender, age, high blood pressure, hyperlipidemia. Diabetes mellitus however, is a risk factor for atherosclerosis, but diabetic patients seldom develop AAA. The reason for this discrepancy is unknown. Increased aortic wall stress seems to be an etiologic factor in the formation, growth and rupture of AAA in man. The aim of our study was to study the wall stress in the abdominal aorta in diabetic patients compared with healthy controls.

METHODS

39 patients with diabetes mellitus and 46 age - and sex matched healthy subjects were examined with B-mode ultrasound to determine the lumen diameter (LD) and intima-media thickness (IMT) in the abdominal aorta (AA) and the common carotid artery (CCA). Diastolic blood pressure (DBP) was measured non-invasively in the brachial artery. LaPlace law was used to calculate circumferential wall stress.

RESULTS

Age, DBP, and LD in the abdominal aorta were not significantly different in the diabetic patients compared to controls. IMT in the AA was larger in the diabetic patients, 0.89+/-0.17 vs 0.73+/-0.11 mm (p<.001). Accordingly aortic wall stress was reduced in the diabetics, 7.8+/-1.7 x 10(5) vs 9.7+/-1.9 x 10(5)dynes/cm(2) (p<.001).

CONCLUSIONS

Wall stress in the abdominal aorta is reduced in diabetes mellitus. This is mainly due to a thicker aortic wall compared to healthy controls. The reduced aortic wall stress coincides with the fact that epidemiological studies have shown a decreased risk of aneurysm development in diabetic patients.

Carotid intima-media thickness as a surrogate marker for cardiovascular disease in intervention studies

BACKGROUND

Cardiovascular trials using clinical endpoints to assess efficacy typically require follow-up of large numbers of participants for 3-5 years. This disadvantage has encouraged the search for well-validated surrogate markers for cardiovascular disease (CVD). These markers may provide earlier indications of efficacy in trials involving fewer participants. One approach gaining interest in recent years is the measurement of atherosclerotic progression, a major underlying cause of CVD.

SCOPE

This review article aims to further substantiate the evidence supporting the use of measurement of carotid intima-media thickness (CIMT) as a surrogate marker for atherosclerosis and cardiovascular risk.

FINDINGS

CIMT has consistently been related to future CVD events in population studies. CIMT is significantly related with other markers for CVD risk, such as elevated levels of risk factors and presence of atherosclerosis in the coronary arteries. Furthermore, almost all lipid-lowering trials and a large number of blood pressure lowering trials have consistently shown a reduction in progression of CIMT. In addition, the ultrasound technique for measuring CIMT is safe and highly reproducible.

CONCLUSION

Thus, CIMT may be used as a surrogate endpoint in clinical trials to enable the benefits of new therapies or regimens to be more rapidly translated into clinical practice.

Endothelial dysfunction in PCOS: role of obesity and adipose hormones

PURPOSE

Polycystic ovary syndrome (PCOS) is an extremely prevalent disorder in which elevated blood markers of cardiovascular risk and altered endothelial function have been found. This study was designed to determine if abnormal carotid intima-media thickness (IMT) and brachial flow-mediated dilation (FMD) in young women with PCOS may be explained by insulin resistance and elevated adipocytokines.

METHODS

A prospective study in 50 young women with PCOS (age: 25.2 +/- 1 years; body mass index [BMI]: 28.7 +/- 0.8) and 50 matched ovulatory controls (age: 25.1 +/- 0.7 years; BMI: 28.5 +/- 0.5) was performed. Carotid IMT, brachial FMD, and blood for fasting glucose, insulin, leptin, adiponectin and resistin were measured.

RESULTS

PCOS, IMT was increased (P <.01), FMD was decreased (P <.01), fasting insulin was increased (P <.01), QUICKI (a marker of insulin resistance) was decreased (P <.01), and adiponectin was lower (P <.05), whereas leptin and resistin were not different compared with matched controls. Whereas BMI or waist/hip ratios did not correlate with IMT or FMD, insulin and QUICKI correlated positively and negatively with IMT (P <.01). There was a significant negative correlation between adiponectin and IMT (P <.05). These correlations were unchanged when adjusting for BMI and the correlation between IMT and adiponectin was unaffected by insulin resistance parameters.

CONCLUSIONS

These data suggest that young women with PCOS have evidence for altered endothelial function. Adverse endothelial parameters were correlated with insulin resistance and lower adiponectin. Both insulin resistance and adiponectin appear to be important parameters. It is hypothesized that the type of fat distribution may influence these factors.

Low-renin (volume dependent) mild-hypertensive patients have impaired flow-mediated and glyceryl-trinitrate stimulated vascular reactivity

BACKGROUND

Low-renin (volume-dependent) hypertension represents 25-30% of all cases of primary hypertension. Endothelial dysfunction and vascular remodeling are associated with hypertension but their relevance to volume-dependent hypertension (VDH) is not yet known. To evaluate this, flow-mediated dilation (FMD) of the brachial artery and the carotid intima-media thickness in the distal common carotid artery were measured and compared between renin-dependent mild-hypertensive patients (RDH) and controls.

METHOD AND RESULTS

The study group comprised 40 mild-hypertensive patients and 25 controls. Plasma renin activity (PRA), plasma aldosterone concentration, angiotensin II and nitrite/nitrate plasma levels were measured. According to PRA, subjects were classified as VDH (<0.6 ng . ml (-1) . h(-1)), or RDH (>0.6 ng . ml(-1) . h (-1)). Vascular function was evaluated by FMD before and after reactive hyperemia (RH) and glyceryl-trinitrate (GTN) administration. FMD in response to RH and GTN in the VDH group when compared with RDH group was 10.2+/-2.8% vs 13.3+/-3.6% (p=0.01); and 16.0+/-3.5% vs 19.9+/-4.5% (p=0.01), respectively.

CONCLUSION

This study showed impaired FMD and reduced GTN response in mildly hypertensive patients with low-renin plasma levels.

Thicker carotid intima layer and thinner media layer in subjects with cardiovascular diseases. An investigation using noninvasive high-frequency ultrasound

BACKGROUND

The thickness of the arterial intima increases and that of the media decreases with increasing age and degree of atherosclerosis. Separate estimates of the individual intima and media layers might therefore be more appropriate than the commonly used method estimating the combined intima-media thickness (IMT).

METHODS AND RESULTS

One hundred consecutive 70-year-old subjects from the PIVUS study were investigated. Separate estimates of the thickness of the carotid artery intima and media wall layers were carried out noninvasively using 25MHz high-frequency ultrasound. Subjects with a diagnosis of cardiovascular disease (CVD), coronary heart disease (CHD), myocardial infarction (MI) or stroke had a significantly thicker intima layer (all P<0.0001) and a thinner media layer (all P<0.05) than healthy subjects. The intima/media thickness ratio also differed significantly between subjects with and without a diagnosis of CVD (0.43+/-0.20versus 0.75+/-0.48, P=0.0002). Subjects with hypertension or hyperlipidemia also had a thicker carotid intima than subjects without these diagnoses (P<0.0005 for both). None of the corresponding intima+media thickness values differed significantly. Similar results were obtained in women and men.

CONCLUSION

Separate assessment of carotid artery intima and media thickness using noninvasive high-frequency ultrasound appears to be of potential value, as a striking difference in intima thickness and the intima/media thickness ratio was found between subjects with and without CVD.

Disparate Associations of a Functional Promoter Polymorphism in PCK1 With Carotid Wall Ultrasound Traits

Background and Purpose— Cytosolic phosphoenolpyruvate carboxykinase (PEPCK; EC 4.1.1.32), encoded by PCK1 , catalyzes the first committed step in gluconeogenesis. We previously showed that a –232C>G promoter polymorphism within a cis -acting element required for basal and cAMP-mediated PCK1 gene transcription results in loss of negative regulation by insulin, contributing to worsened metabolic control in the context of insulin resistance. We hypothesized that this polymorphism would be associated with carotid atherosclerosis in a sample of 150 aboriginal Canadians.

Methods— Dependent variables were 2 distinct carotid traits, namely intima-media thickness (IMT) assessed using B-mode ultrasound and total carotid plaque volume (TPV) assessed using 3D ultrasound.

Results— Multivariate analysis showed significant but opposite associations of PCK1 genotype with these traits. Specifically, subjects with the PCK1 –232G/G genotype had more carotid IMT (0.80±0.02 versus 0.73±0.03 mm; P =0.007) but less TPV (0.10±0.09 versus 0.38±0.13; P =0.03) than subjects with other genotypes.

Conclusions— The findings connect the key enzyme in gluconeogenesis with atherosclerosis. The meaning of the opposing associations of PCK1 genotype with IMT and TPV is unclear; more work is required to confirm whether these might be distinct quantitative traits with different biological determinants.

Age-related increase in wall stress of the human abdominal aorta: an in vivo study

BACKGROUND

The regulation of wall stress in the abdominal aorta (AA) of humans might be of specific interest, because the AA is the most common site for aneurysm formation in which wall stress seems to be an important pathophysiological factor. We studied the age-related changes in wall stress of the AA in healthy subjects, with the common carotid artery (CCA) as a comparison.

METHODS

A total of 111 healthy subjects were examined with B-mode ultrasonography to determine the lumen diameter and intima-media thickness (IMT) in the AA and the CCA.

RESULTS

Aortic IMT was affected by age in men and by both age and lumen diameter in women. Carotid IMT was affected by age and pulse pressure in both men and women. Wall stress was higher in the AA than in the CCA (P < .001), and men had higher wall stress than women in both the AA (P < .001) and the CCA (P < .05). Furthermore, wall stress was constant during life in the CCA of men and women and in the AA of women. In the male aorta, however, wall stress increased with age (P < 0.01).

CONCLUSIONS

Arterial diameters increase with age, and a compensatory thickening of the arterial wall prevents the circumferential wall stress from increasing. However, this compensatory response is insufficient in the male AA and results in an increase in stress with age. These findings might explain the propensity for aneurysms to develop in the AA of men.

Differences between carotid wall morphological phenotypes measured by ultrasound in one, two and three dimensions

Ultrasound measurements are both surrogate markers and risk factors for atherosclerosis end points. Carotid intima-media thickness (IMT) is most commonly used, but ultrasound can also define structures in higher spatial dimensions, such as total plaque area (TPA) and total plaque volume (TPV). Because there are minimal data regarding the relationship between IMT, TPA and TPV, we measured these variables in 272 Oji-Cree subjects. We found pairwise correlations for IMT:TPA, IMT:TPV and TPA:TPV of 0.507, 0.588 and 0.846, respectively (transformed variables, all P <0.0001). In a subset of 168 subjects with complete cardiovascular risk factor data, we performed multivariate regression analysis to identify sources of variation for IMT, TPA and TPV. We found that the ultrasound traits showed different correlations with individual cardiovascular risk factors. In particular, IMT was significantly associated with hypertension, TPA with smoking and plasma cholesterol, and TPV with diabetes. Therefore, these ultrasound measures of carotid artery morphology, while somewhat correlated, likely represent distinctive quantitative traits with different biological determinants, as underscored by different risk factor associations in the multivariate regression analysis. Because the measurements have different implications and determinants, investigators might need to be selective about the particular measurements they choose for specific applications.

Comparison between three-dimensional volume-selective turbo spin-echo imaging and two-dimensional ultrasound for assessing carotid artery structure and function

PURPOSE

To compare a volume-selective three-dimensional turbo spin echo (TSE) technique with ultrasound (US) for assessing carotid artery wall structure and function.

MATERIALS AND METHODS

A three-dimensional volume-selective TSE technique was used to image the carotid artery in 10 healthy subjects and five hypertensive subjects (each of whom were scanned three times while they received different hypertension treatments). Lumen and wall area were measured on MR images. Two-dimensional US measurements of the intima-media thickness (IMT) and lumen diameter were taken in three orientations through a single cross section. The lumen area change over the cardiac cycle was used to determine distension. For validation, a Bland-Altman analysis was used to compare the vessel wall and lumen areas measured by three-dimensional MRI volumes with those obtained by US scans.

RESULTS

Agreement between the two methods was found. The mean difference in distension between US and MRI was 1.2% (+/-5.1%). For the wall area measurements, good agreement was shown, but there was a systematic difference due to the visualization of the adventitia by MRI. Both techniques offer an easy way to objectively measure lumen indices. MRI can provide the complete circumference over the length of a vessel, while US is flexible and relatively inexpensive. The application of US is limited, however, when subjects are poorly echogenic. A difference between hypertensive and healthy subjects was found.

CONCLUSION

There was a good agreement between MRI and the clinically established two-dimensional US method. The MRI method has the advantage of providing increased vessel coverage, which permits one to assess localized abnormalities without assuming vessel uniformity.

Carotid intima-media thickness measurements in intervention studies: design options, progression rates, and sample size considerations: a point of view

BACKGROUND

Carotid intima-media thickness (CIMT) measurements are currently widely used in randomized controlled trials (RCTs) to study the efficacy of interventions. In designing a RCT with CIMT as a primary outcome, several ultrasound options may be considered. We discuss the various options and provide a pooled estimate of CIMT progression. In addition, we quantify the effect of these choices on the sample size for a RCT.

SUMMARY OF COMMENT

To estimate the average CIMT progression rate, we performed a pooled analysis using CIMT progression rates of control groups from published RCTs. The pros and cons of the following ultrasound options are discussed: which arterial segments may be studied; whether near and far wall CIMT measurements should be performed; whether a single image (1 angle of interrogation) or multiple images (more angles of interrogation) should be used; whether a manual or an automated edge detection reading system should be used; and whether images should be read in a random fashion or in batches. The pooled analysis showed an annual rate of change in mean common CIMT of 0.0147 mm (95% CI, 0.0122 to 0.0173) and in mean maximum CIMT of 0.0176 mm (95% CI, 0.0149 to 0.0203).

CONCLUSIONS

Given the current evidence together with our experience with recently developed ultrasound protocols, we favor the use of mean maximum CIMT rather than mean common CIMT as the primary outcome measure in RCTs designed to evaluate the efficacy of pharmacological and nonpharmacological interventions in carotid artery atherosclerosis.

Noninvasive ultrasound measurements of aortic intima-media thickness: implications for in vivo study of aortic wall stress

OBJECT

The abdominal aorta (AA) has a predilection for aneurysm formation. An etiologic factor may be underlying aortic wall stress. The purpose of this study was to examine whether the intima-media thickness (IMT) of the AA, as a surrogate to arterial wall thickness, can be measured noninvasively with satisfactory results to calculate circumferential wall stress, and to evaluate regional and gender differences in wall stress.

METHODS

Sixty-five middle-aged healthy subjects were examined with B-mode ultrasound to determine the diameter and IMT in the infrarenal AA, common carotid artery (CCA), common femoral artery (CFA), and popliteal artery (PA). Blood pressure was measured noninvasively in the brachial artery. Wall stress was calculated according to the law of LaPlace.

RESULTS

Intraobserver variability for the IMT in the AA showed a coefficient of variation of 11%. IMT was thickest in the AA compared with the CCA, CFA, and PA (P <.001). There was a gender difference in IMT in the CFA (P <.05) and PA (P <.01) but not in the AA. Greater wall stress was found in the AA than in the CCA (P <.001) and PA (P <.001), with men having greater wall stress in all studied arterial regions.

CONCLUSIONS

Aortic IMT can be satisfactorily studied in vivo with noninvasive B-mode ultrasound. There are gender differences in IMT and wall stress, and the largest wall stress is found in the AA in men, which might be important in aneurysm development.

Promoter polymorphism in the endotoxin receptor (CD14) is associated with increased carotid atherosclerosis only in smokers: the Carotid Atherosclerosis Progression Study (CAPS)

BACKGROUND AND PURPOSE

The risk of atherosclerosis from endotoxemia is increased in smokers. Endotoxin is a potent mediator of inflammation, and smokers have elevated plasma levels of endotoxin. The endotoxin receptor CD14 can enhance the endotoxin-neutralization capacity of plasma. A functional polymorphism in the promoter region of the CD14 gene (CD14 -159C/T) was studied to determine its impact on common carotid artery (CCA) intima-media thickness (IMT) and any interactions with environmental inflammatory stimuli.

METHODS

A community population (n=992; aged 50 to 65 years) underwent genotypic examination for the CD14 -159 polymorphism by restriction fragment length polymorphism analysis.

RESULTS

The CC genotype was associated with increased CCA IMT. The age- and sex-adjusted odds ratio for IMT above the 75th percentile was 1.63 (95% CI, 1.19 to 2.24; P=0.002) and 1.70 (95% CI, 1.18 to 2.44; P=0.004) after additional adjustment for conventional risk factors. This gene effect was found only in current smokers and ex-smokers. Multivariate analysis in this group (n=503) increased the odds ratio to 2.02 (95% CI, 1.23 to 3.34; P=0.006). No significant interactions were found in nonsmokers or with alcohol consumption.

CONCLUSIONS

The CD14 -159 polymorphism is associated with increased CCA IMT in smokers from a general population. CD14 may modulate the inflammatory effects of smoking in atherogenesis.

Carotid intima-media thickness, arterial stiffness and risk of cardiovascular disease: current evidence

AIMS

Over recent decades the interest in cardiovascular epidemiology has broadened from studies on causes and consequences of elevated cardiovascular risk factors to include research on causes and consequences of atherosclerosis and associated arterial wall abnormalities. One of the underlying reasons was that established cardiovascular risk factors were insufficiently accurate in identifying those individuals who will suffer from cardiovascular disease in the future and measures of subclinical atherosclerosis may enhance the precision of these predictions and thus enable better-tailored medical care to be provided. The usefulness of measuring subclinical atherosclerosis is conditional on evidence that presence of subclinical atherosclerosis confers an increased risk of cardiovascular disease and that favourable changes in subclinical atherosclerosis parallel reductions in risk. We aimed at providing an overview of epidemiological data on carotid intima-media thickness (CIMT) and arterial stiffness measurements and their relation to risk of cardiovascular disease.

METHODS

We reviewed the published epidemiological data.

RESULTS AND CONCLUSION

CIMT is a good indicator of cardiovascular risk and provides a graded measure of vascular damage: no clear CIMT level above which the cardiovascular risk appears to increase considerably The evidence for arterial stiffness, assessed as carotid distensibility or aortic pulse wave velocity, as an indicator for risk of cardiovascular disease is restricted to subjects with either hypertension or end-stage renal disease or based on small studies in renal transplant patients and elderly. Evidence to indicate that information on carotid intima-media thickness or arterial stiffness, additional to established cardiovascular risk factors, helps to distinguish subjects into those with a high and those with a low absolute risk of cardiovascular disease is limited, but needed. Also, information on the direct comparison of both arterial stiffness measures in their ability to predict cardiovascular disease is needed.

Predictable tissue shrinkage during frozen section histopathologic processing for Mohs micrographic surgery

BACKGROUND

When confronted with a histologic specimen that is appreciably smaller than the same tissue specimen immediately after acquisition, the Mohs surgeon is faced with two possibilities, namely that the tissue has either shrunken during laboratory processing or that the histologic specimen is incomplete due to the introduction of technical errors during embedding, cutting, or staining of the skin specimen. Because the entire objective of Mohs micrographic surgery is to precisely examine the entire surgical margin of skin specimens, the surgeon must be able to determine that any size discrepancies introduced during laboratory processing are not related to incomplete surgical specimens. Although there are anecdotal suggestions that skin, like other human tissues, undergoes some degree of shrinkage during routine frozen section processing, the exact nature and magnitude of this phenomenon has not been previously investigated.

OBJECTIVE

To quantify the degree of tissue shrinkage in Mohs micrographic surgical specimens processed with routine frozen sections and subsequent hematoxylin and eosin staining.

METHODS

A total of 117 Mohs surgery patients (135 cutaneous tumors) were prospectively enrolled. The dimensions of initial stage surgical specimens were determined after removal from the patient, after freezing in a mounting medium, after placement on a glass microscopic slide, and after hematoxylin and eosin staining. Statistical analyses were performed in order to determine the significance of any discrepancies in specimen sizes introduced during laboratory processing.

RESULTS

Skin specimens processed by frozen section techniques during Mohs micrographic surgery undergo statistically significant alterations in length. On average the measurements of specimens at the conclusion of histologic processing were 11.6% shorter than the measurements of the same specimens obtained immediately after surgical excision. Tissue specimens obtained from the trunk or extremities showed a greater degree of tissue shrinkage (16.3%) than specimens obtained from the head and neck (10.2%).

CONCLUSIONS

Our results support anecdotal suggestions that skin specimens do indeed shrink during frozen section processing. By realizing that frozen section specimens can be expected to show some slight degree of shrinkage, the Mohs surgeon can appreciate situations that might allow greater confidence that a smaller specimen is nonetheless representative of the entire lateral and deep surgical margins.

Accuracy of in vivo carotid B-mode ultrasound compared with pathological analysis: intima-media thickening, lumen diameter, and cross-sectional area

BACKGROUND AND PURPOSE

This study aimed to determine the correlation of in vivo ultrasound measurements of intima-media thickening (IMT), lumen diameter, and cross-sectional area of the common carotid artery (CCA) with corresponding measurements obtained by gross pathology and histology.

METHODS

Sixty-six moribund neurological patients (mean age 71 years) underwent B-mode ultrasound of the CCA a few days before death. During autopsy, carotid specimens were removed in toto. Carotid arteries were ligated and cannulated for injection of a hydrophilic embedding material under standardized conditions. The carotid bifurcation was frozen and cut manually in 3-mm cross slices. Digital image analysis was carried out to determine the diameter and the cross-sectional area of the frozen slices of the CCA. IMT was assessed by light microscope. Ultrasonic and planimetric data were compared.

RESULTS

Mean measurements of lumen diameter and cross-sectional area were 7.13+/-1.27 mm and 0.496+/-0.167 cm(2), respectively, by ultrasound, and 7.81+/-1.45 mm and 0.516+/-0.194 cm(2), respectively, by planimetric analysis of the unfixed redistended carotid arteries (R(2)=0.389 and 0.497). The mean IMT was 1.005+/-0.267 mm by ultrasound and 0.67+/-0.141 mm histologically, resulting in a mean difference of -31%.

CONCLUSIONS

Transcutaneous B-mode ultrasound provides a reliable approach for in vivo measurements of the cross-sectional area and, less exactly, of the lumen diameter of the CCA. Compared with histological results, in vivo ultrasound measurements of the IMT are systematically larger.