Repeated visual and computer-assisted carotid plaque characterization in a longitudinal population-based ultrasound study: the Tromsø study

Urinary orosomucoid is associated with diastolic dysfunction and carotid arteriopathy in the general population. Cross-sectional data from the Tromsø study

Objectives. Urinary albumin excretion is a risk marker for cardiovascular disease (CVD). Studies suggest that urinary orosomucoid may be a more sensitive marker of general endothelial dysfunction than albuminuria. The aim of this population-based cross-sectional study was to examine the associations between urinary orosomucoid to creatinine ratio (UOCR), urinary albumin to creatinine ratio (UACR) and subclinical CVD. Design. From the Tromsø Study (2007/2008), we included all men and women who had measurements of urinary orosomucoid (n = 7181). Among these, 6963 were examined with ultrasound of the right carotid artery and 2245 with echocardiography. We assessed the associations between urinary markers and subclinical CVD measured as intima media thickness of the carotid artery, presence and area of carotid plaque and diastolic dysfunction (DD). UOCR and UACR were dichotomized as upper quartile versus the three lowest. Results. High UOCR, adjusted for UACR, age, cardiovascular risk factors and kidney function, was associated with presence of DD in men (OR: 3.18, 95% CI [1.27, 7.95], p = .013), and presence of plaque (OR: 1.20, 95% CI [1.01, 1.44], p = .038) and intima media thickness in women (OR: 1.34, 95% CI [1.09, 1.65], p = .005). Analyses showed no significant interaction between sex and UOCR for any endpoints. UACR was not significantly associated with DD, but the associations with intima media thickness and plaque were of magnitudes comparable to those observed for UOCR. Conclusions. UOCR was positively associated with subclinical CVD. We need prospective studies to confirm whether UOCR is a clinically useful biomarker and to study possible sex differences.

Effect of menopausal hormone therapy on arterial wall echomorphology: Results from the Early versus Late Intervention Trial with Estradiol (ELITE)

OBJECTIVE

To evaluate the effect of hormone therapy (HT) on arterial wall composition by ultrasound.

BACKGROUND

The effect of HT on the progression of subclinical atherosclerosis has been well-described using measurements of common carotid artery (CCA) wall thickness. However, it is unknown whether the change in arterial wall anatomic structure is accompanied by an effect of HT on arterial wall composition.

METHODS

A total of 643 healthy postmenopausal women divided into two strata according to the time since menopause (<6 years, the early-postmenopause group; or >10 years, the late-postmenopause group) were randomized to receive either active treatment or placebo. For hysterectomized women, the active treatment was oral micronized 17β-estradiol 1 mg/day; for women with a uterus, 4% vaginal micronized progesterone gel 45 mg/day for 10 days each month was added to the estradiol regimen. Gray-scale median of the CCA intima-media complex (IM-GSM), a (unitless) measurement of arterial wall composition based on echogenicity, was determined by high-resolution B-mode ultrasonography. Lower IM-GSM, or less echogenicity, indicates more atherosclerosis. IM-GSM and serum estradiol (E2) concentration were assessed every 6 months over a median 4.8-year trial period. Linear mixed effects regression models were used for all analyses.

RESULTS

Overall, IM-GSM progression/year had a negative trajectory, reflecting reduction in echogenicity over time (worsening atherosclerosis). HT effects on IM-GSM progression/year differed by postmenopause strata (interaction p-value = 0.02). IM-GSM progression/year (95% CI) in the early postmenopause group randomized to HT was -0.50 (-0.82, -0.18)/year compared with -1.47 (-1.81, -1.13)/year among those randomized to placebo (p-value <0.0001). In the late postmenopause group, the annual IM-GSM progression rate did not significantly differ between HT and placebo (p = 0.28). Higher mean on-trial E2 (pg/ml) levels were associated with higher IM-GSM progression, indicating less atherosclerosis progression in all women (β (95% CI) = 0.006 (0.0003, 0.01), p = 0.04). For each pg/dl E2, IM-GSM progression/year was 0.007 ((-0.0002, 0.01), p = 0.056) in the early and 0.003 ((-0.006, 0.01), p = 0.50) in the late postmenopause group (interaction p-value = 0.51). CIMT progression rate (μm/year) was significantly inversely associated with the IM-GSM progression (β (95% CI) = -4.63 (-5.6, -3.7), p < 0.001).

CONCLUSIONS

HT, primarily with oral estradiol, reduced atherogenic progression of arterial wall composition in healthy postmenopausal women who were within 6 years from menopause.

TRIAL REGISTRATION NUMBER

NCT01553084.

Effect of adiposity on differences in carotid plaque burden in studies conducted in Norway and Russia: a cross-sectional analysis of two populations at very different risk of cardiovascular mortality

OBJECTIVES

Large differences exist in the burden of cardiovascular disease (CVD) between Russia and Western European countries including Norway. Obesity prevalence may contribute to the differences. We investigated whether difference in the level of adiposity, assessed using body mass index and waist-to-hip ratio(WHR), could explain intercountry differences in the burden of carotid plaque, a measure of atherosclerosis, in the populations.

DESIGN

Cross-sectional analysis. Logistic and linear regression models were used.

SETTING

We used population-based cross-sectional Know Your Heart (KYH) study in Russia and the Tromsø 7 study (Tromsø 7) in Norway.

PARTICIPANTS

3262 and 1800 men and women aged 40-69 years in KYH and Tromsø 7, respectively.

PRIMARY AND SECONDARY OUTCOME

The presence of carotid plaques and plaque score assessed using ultrasound.

RESULTS

The presence of carotid plaques and plaque score were higher in KYH than Tromsø 7 regardless of age group and sex. A positive association between carotid plaque burden and adiposity was found (OR of having at least one plaque per SD in WHR 1.18 (95% CI 1.06 to 1.31) for men; 1.15 (1.06 to 1.25) for women)) adjusted for age, smoking and education in a pooled analysis of the two studies. There was little evidence of the interaction between study and adiposity. These effects did not differ between the two studies. However, neither adiposity nor CVD risk factors (smoking, systolic blood pressure, cholesterol, glycosylated haemoglobin) explained the higher carotid plaque burden in KYH compared with Tromsø 7.

CONCLUSION

Adiposity, especially abdominal adiposity, is a risk factor for carotid plaque in Russia and Norway, although neither adiposity nor established CVD risk factors explained the higher plaque burden in Russia. To reduce the CVD burden in Russia, beyond prevention and treatment of adiposity, further research is required to understand why Russia has a high burden of atherosclerosis.

The association between anthropometric measures of adiposity and the progression of carotid atherosclerosis

Background

Few reports are available on the contribution of general and abdominal obesity to the progression of carotid atherosclerosis in late adulthood. This study investigated the impact of four simple anthropometric measures of general and abdominal obesity on the progression of carotid atherosclerosis and the extent to which the association between adiposity and the progression of plaque burden is mediated by cardiometabolic markers.

Methods

Four thousand three hundred forty-five adults (median age 60) from the population-based Tromsø Study were followed over 7 years from the first carotid ultrasound screening to the next. The progression of carotid atherosclerosis was measured in three ways: incidence of plaques in previously plaque-free participants; change in the number of plaques; and total plaque area (TPA). We used generalised linear models to investigate the association between each adiposity measure – body mass index (BMI), waist circumference (WC), waist-to-hip ratio (WHR), and waist-to-height ratio (WHtR) – and each outcome. Models were adjusted for potential confounders (age, sex, smoking, education, physical activity). The pathways through which any associations observed might operate were investigated by further adjusting for cardiometabolic mediators (systolic blood pressure, cholesterol, and HbA1c).

Results

There was little evidence that adiposity was related to the formation of new plaques during follow-up. However, abdominal adiposity was associated with TPA progression. WHtR showed the largest effect size (mean change in TPA per one standard deviation (SD) increase in WHtR of 0.665 mm², 95% confidence interval 0.198, 1.133) while BMI showed the smallest. Effect sizes were substantially reduced after the adjustment for potential mediators.

Conclusions

Abdominal obesity indirectly measured with WC seems more strongly associated with the progression of TPA than general obesity. These associations appear to be largely mediated by known cardiometabolic markers.

Ultrasound risk marker variability in symptomatic carotid plaque: impact on risk reclassification and association with temporal variation pattern

Purpose

Ultrasound examinations of atherosclerotic carotid plaques can be used to calculate risk markers associated with plaque vulnerability. Recent studies demonstrate significant inter-frame variability in risk markers. Here, we investigate risk marker variability in symptomatic plaques and its impact on reclassification of plaque vulnerability, as well as its association with the shape of the temporal variation over the cardiac cycle.

Methods

56 patients with symptomatic carotid stenosis were included in this study. 88 plaques were identified and the plaque risk markers size (area), echogenicity (gray scale median, GSM) and heterogeneity (coarseness) were measured in all frames of ultrasound B-mode image sequences. Inter-frame variability was quantified using the coefficient of variation (CV).

Results

Inter-frame variabilities of the risk markers were area CV 5–8%; GSM CV 4–7%; coarseness CV 8–15% and was in general significantly lower in large as compared to smaller plaques. The variability in GSM risk marker caused a reclassification of vulnerability in 30 to 38% of the plaques. Temporal variations in GSM with a heart rate periodic or drift/trending pattern were found in smaller plaques (< 26 mm²), whereas random pattern was found in larger plaques. In addition, hypoechoic plaques (GSM < 25) were associated with cyclic variation pattern, independent of their size.

Conclusions

Risk marker variability causes substantial reclassification of plaque vulnerability in symptomatic patients. Inter-frame variation and its temporal pattern should be considered in the design of future studies related to risk markers.

Inter-sonographer reproducibility of carotid ultrasound plaque detection using Mannheim consensus in subclinical atherosclerosis

AIMS

To determine the inter-sonographer reproducibility of carotid ultrasound plaque detection using Mannheim consensus in a subclinical population and evaluate associations related to the reproducibility.

METHODS AND RESULTS

Bilateral ultrasound screening for carotid plaques defined by Mannheim consensus was performed on 106 subclinical participants. Two different sonographers scanned the same participant, and reproducibility of plaque detection was measured by Cohens kappa. Associations with reproducibility were evaluated by comparing wall, and plaque characteristics between subjects with plaques identified in one and both scans. In general, the inter-sonographer reproducibility of plaque detection was substantial with a kappa value of 0·70 (95% CI 0·60-0·80). Plaques detected in only one scan had significantly lower plaque area and plaque thickness (6·82 mm² and 1·45 mm) as compared to plaques detected in both scans (11·65 mm² and 1·96 mm, P<0·001).

CONCLUSION

Minor carotid plaques contribute to decreased reproducibility as compared to large plaques when screening for subclinical atherosclerosis using Mannheim consensus. Using an alternative plaque definition based on plaque thickness >1.5 mm and plaque area >10 mm² could increase the reproducibility of plaque detection in subclinical atherosclerosis.

Risk Marker Variability in Subclinical Carotid Plaques Based on Ultrasound is Influenced by Cardiac Phase, Echogenicity and Size

Identification of risk markers based on quantitative ultrasound texture analysis of carotid plaques has the ability to define vulnerable components that correlate with increased cardiovascular risk. However, data describing factors with the potential to influence the measurement variability of risk markers are limited. The aim of this study was to evaluate the influence of electrocardiogram-guided image selection, plaque echogenicity and area on carotid plaque risk markers and their variability in asymptomatic carotid plaques. Plaque risk markers were measured in 57 plaques during three consecutive heartbeats at two cardiac cycle time instants corresponding to the electrocardiogram R-wave (end diastole) and end of T-wave (end systole), resulting in six measurements for each plaque. Risk marker variability was quantified by computing the coefficient of variation (CV) across the three heartbeats. The CV was significantly higher for small plaques (area <15 mm2, 10%) than for large plaques (area >15 mm2, 6%) (p < 0.001) in measurements of area, and the CV for measurements of gray-scale median were higher for echolucent plaques (<40, 15%) than for echogenic plaques (>40, 9%) (p < 0.001). No significant differences were found between systole and diastole for the mean of any risk marker or the corresponding CV value. However, in a sub-analysis, the echolucent plaques were found to have a higher CV during systole compared with diastole. The variability also caused plaque type reclassification in 16% to 25% of the plaques depending on cutoff value. The results of this study indicate that echolucent and small plaques each contribute to increased risk marker variability. Based on these results, we recommend that measurements in diastole are preferred to reduce variation, although we found that it may not be possible to characterize small plaques accurately using contemporary applied risk markers.

Fish consumption, fish oil supplements and risk of atherosclerosis in the Tromsø study

BACKGROUND

Whether long-chain n-3 PUFAs of marine origin have an anti-atherogenic effect in the general population has hardly been studied. In this population-based study, we hypothesized that fatty fish and fish oil intake protect against development of novel atherosclerotic plaques and is associated with reduced plaque size.

METHODS

We obtained questionnaire-based information on fish consumption and carotid ultrasonography from 3900 persons aged 45-74 years. The questionnaires were validated by measuring serum concentrations of PUFAs and triglycerides in a subgroup. At follow-up seven years later, 2983 (76%) went through a second ultrasound scanning. Logistic regression and general linear models were used to analyze the outcome (plaque presence and plaque area) as a function of fish consumption, including analyses stratified on fish oil supplements.

RESULTS

At baseline, lean fish intake < 1 time/week vs. 1-1.9 times/week was associated with risk of plaque (OR 1.34, 95% CI 1.03-1.76). Fatty fish intake and use of fish oil supplements were not statistically significantly associated with atherosclerosis at baseline. In persons without plaque at baseline, total fish consumption ≥3 times/week vs. 1-1.9 times/week was associated with risk of novel plaque (OR 1.32, 95% CI 1.01-1.73) and larger plaque area (1.76 mm² vs. 1.46 mm², p = 0.02) at follow-up. Adjustments for use of fish oil supplements had no impact on the associations, and no interactions were seen between total, fatty or lean fish consumption and fish oil intake.

CONCLUSIONS

We found no protective effect of fatty fish eating or fish oil supplements on atherosclerotic plaque formation or plaque area in a general population. Lean fish consumption was associated with a reduced risk for plaque in cross-sectional analysis, suggesting that the beneficial effects of fish consumption on atherosclerosis may be mediated through other mechanisms than n-3 PUFAs.

Joint Effect of Carotid Plaque and C-Reactive Protein on First-Ever Ischemic Stroke and Myocardial Infarction?

Background

The joint effect of atherosclerosis and CRP (C‐reactive protein) on risk of ischemic stroke (IS) and myocardial infarction (MI) has been sparsely studied. The aim of this study was to explore whether CRP mediates the risk of events in subjects with prevalent carotid plaque, examine synergism, and test whether CRP and carotid plaque add to risk prediction beyond traditional risk factors.

Methods and Results

CRP and carotid total plaque area (TPA) were measured in 10 109 participants in the Tromsø Study from 1994 to 2008. Incident IS (n=671) and MI (n=1079) were registered until December 31, 2013. We calculated hazard ratios (HRs) of MI and IS according to categories of CRP (<1, 1–3, and >3 mg/L) and plaque status (no plaque and TPA below and above median) in Cox proportional hazard models with time‐varying covariates. Multivariable‐adjusted CRP >3 versus <1 mg/L was associated with risk of IS (HR, 1.84; 95% confidence interval, 1.49–2.26) and MI (HR, 1.46; 95% confidence interval, 1.23–1.73). TPA above median versus no plaque was associated with risk for IS (HR, 1.65; 95% confidence interval, 1.36–2.01) and MI (HR, 1.64; 95% confidence interval, 1.41–1.92). In participants with plaque, adjustment for CRP minimally attenuated the risk estimates. The highest incidence rates for MI and IS were seen in the group with both CRP >3 mg/L and TPA is above the median. TPA and CRP combined added to risk prediction beyond traditional risk factors.

Conclusions

The simultaneous presence of subclinical atherosclerosis and elevated CRP was associated with increased risk of IS and MI. The combined assessment of subclinical atherosclerosis and inflammatory biomarkers may improve cardiovascular disease risk stratification.

Prevalence of Carotid Plaque in a 63- to 65-Year-Old Norwegian Cohort From the General Population: The ACE (Akershus Cardiac Examination) 1950 Study

Background

New data on extracranial carotid atherosclerosis are needed, as improved ultrasound techniques may detect more atherosclerosis, the definition of plaque has changed over the years, and better cardiovascular risk control in the population may have changed patterns of carotid arterial wall disease and actual prevalence of established cardiovascular disease. We investigated the prevalence of atherosclerotic carotid plaques and carotid intima–media thickness (cIMT) and their relation to cardiovascular risk factors in a middle‐aged cohort from the general population.

Methods and Results

We performed carotid ultrasound in 3683 participants who were born in 1950 and included in a population‐based Norwegian study. Carotid plaque and cIMT were assessed according to the Mannheim Carotid Intima–Media Thickness and Plaque Consensus, and a carotid plaque score was used to calculate atherosclerotic burden. The participants were aged 63 to 65 years, and 49% were women. The prevalence of established cardiovascular disease was low (10%), but 62% had hypertension, 53% had hypercholesterolemia, 11% had diabetes mellitus, and 23% were obese. Mean cIMT was 0.73±0.11 mm, and atherosclerotic carotid plaques were present in 87% of the participants (median plaque score: 2; interquartile range: 3). Most of the cardiovascular risk factors, with the exception of diabetes mellitus, obesity and waist–hip ratio, were independently associated with the plaque score. In contrast, only sex, hypertension, obesity, current smoking, and cerebrovascular disease were associated with cIMT.

Conclusions

We found very high prevalence of carotid plaque in this middle‐aged population, and our data support a greater association between cardiovascular risk factors and plaque burden, compared with cIMT.

Clinical Trial Registration

URL: https://www.clinicaltrials.gov. Unique identifier: NCT01555411.

The contribution of obesity to carotid atherosclerotic plaque burden in a general population sample in Norway: The Tromsø Study

BACKGROUND AND AIMS

Few studies have investigated the association of different measures of adiposity with carotid plaque. We aimed to investigate and compare the associations of four measures of adiposity: body mass index (BMI), waist circumference (WC), waist-to-hip ratio (WHR), and waist-to-height ratio (WHtR) with the presence of carotid plaque and total plaque area (TPA) in the right carotid artery.

METHODS

We included 4906 individuals aged 31-88 years who participated in a population-based study with ultrasonography of the right carotid artery. Adiposity measures were converted to sex-specific SD units to allow comparison of effect sizes. TPA was log transformed due to its skewed distribution. Logistic and linear regression models were used respectively to investigate the association of each adiposity measure with the presence of plaque and with log-transformed TPA. Estimates were adjusted for potential confounders and mediators such as blood pressure and lipids.

RESULTS

After adjustment for age, sex, smoking, and education level, there was strong evidence of an association between all adiposity measures and log-transformed TPA, whereas only WHR was weakly associated with presence of plaque. WHR showed the largest adjusted effect size for both log-transformed TPA (beta 0.055, 95%CI 0.028-0.081) and the presence of plaque (OR 1.07, 95%CI 1.01-1.15). Adjustment for mediators led to appreciable attenuation of observed effects.

CONCLUSIONS

Adiposity is more consistently associated with extent of plaque burden than with whether an individual does or does not have any plaque. There was evidence that established biomarkers mediate much of this association. Abdominal adiposity appears to show the strongest effect.

Interleukin-6 is an independent predictor of progressive atherosclerosis in the carotid artery: The Tromsø Study

BACKGROUND AND AIMS

Novel biomarkers are linked to cardiovascular disease (CVD). The aim of the present study was to investigate the association between 28 blood biomarkers and the formation and progression of carotid plaque.

METHODS

In a nested case control study with 703 participants from the population based Tromsø Study, a large biomarker panel was measured in blood obtained at baseline. Carotid ultrasound was assessed both at baseline and at 6 years of follow-up. Four groups were defined: Group 1: no plaque at baseline or at follow-up (reference group); Group 2: novel plaque at follow-up; Group 3: stable plaque at follow-up; Group 4: progression of plaque at follow-up. By multinomial logistic regression analyses, we assessed the risk of being in the different plaque groups with regard to traditional cardiovascular risk factors and levels of biomarkers at baseline.

RESULTS

Adjusted for traditional risk factors, interleukin-6 (IL-6) was an independent predictor of plaque progression (OR 1.44, 95% CI 1.12-1.85 per SD increase in IL-6 level). This result remained significant after inclusion of other novel biomarkers to the model, and when subjects with former CVD were excluded. Neopterin was protective of novel plaque formation (OR 0.73, 95% CI 0.57-0.93). Myeloperoxidase and Caspase-1 were independent predictors of plaque progression, but this effect disappeared when excluding subjects with former CVD.

CONCLUSIONS

IL-6 is an independent predictor of plaque progression, suggesting that it may be a marker of progressive atherosclerosis in the general population and that its central role in CVD may be related to promotion of plaque growth.

C-reactive protein in atherosclerosis - A risk marker but not a causal factor? A 13-year population-based longitudinal study: The Tromsø study

BACKGROUND AND AIMS

CRP predicts cardiovascular disease (CVD) in large epidemiologic studies. The aim of the present study was to elucidate the role of CRP in atherosclerosis formation and progression in a prospective population-based study.

METHODS

6503 middle-aged subjects from The Tromsø study had serum CRP, carotid ultrasound and complete covariate data collected at baseline in 1994. Of these, 4730 and 2917 attended follow-up surveys with repeated assessments in 2001 and 2007, respectively. The cross-sectional associations between CRP and subclinical carotid atherosclerosis, and the longitudinal associations between baseline CRP and novel plaque formation and plaque progression were assessed in generalized estimating equations and linear mixed models stratified by sex.

RESULTS

At baseline, traditional risk factors and plaque prevalence increased by CRP risk categories (<1 mg/L, 1-3 mg/L, and >3 mg/L) in both sexes. In cross-sectional analyses, multivariable-adjusted CRP was associated with plaque prevalence and total plaque area (TPA) in men and women. Age-adjusted baseline CRP >3 mg/L compared to CRP <1 mg/L predicted novel plaque formation (OR 1.44, CI 1.08-1.92) and TPA progression (β = 0.0.029 (CI, 0.003-0.056)) in men, but not in women. In neither men nor women was baseline CRP a predictor of TPA-progression or novel plaque formation when adjusted for traditional risk factors.

CONCLUSIONS

CRP was associated with plaque presence and TPA in cross-sectional analyses, but was not an independent predictor of novel plaque formation or plaque progression. Our findings suggest that CRP may link to CVD by other mechanisms than promoting formation and progression of atherosclerotic plaques.

Impact of Venous Thromboembolism on the Formation and Progression of Carotid Atherosclerosis: The Tromsø Study

Venous thromboembolism (VTE) is associated with increased risk of arterial cardiovascular diseases (CVD), and development of atherosclerosis secondary to VTE may be an intermediate between VTE and CVD. Therefore, we aimed to investigate whether incident VTE was associated with subsequent carotid atherosclerosis formation and progression in a population-based observational study. Subjects attending two or more ultrasound examinations of the right carotid artery, with measurement of total plaque area (TPA), in the Tromsø Study in 1994–1995, 2001–2002, and/or 2007–2008 were eligible. We identified 150 subjects diagnosed with first-lifetime VTE between the initial and follow-up visit, and randomly selected 600 age- and sex-matched subjects without VTE between the visits. Subjects with VTE and carotid plaque(s) at the first visit had 4.1 mm ² (β: 4.13, 95% CI: −1.72 to 9.98) larger change in TPA between the first and second visit compared with subjects without VTE after adjustment for change in high-sensitivity C-reactive protein (hs-CRP) and traditional atherosclerotic risk factors. The association remained after restricting the analyses to VTE events diagnosed in the first half of the time interval between the carotid ultrasounds (β: 4.02, 95% CI: −3.66 to 11.70), supporting that the change in TPA occurred subsequent to the VTE. No association was found between VTE and novel carotid plaque formation. In conclusion, we found a possible association between VTE and atherosclerosis progression in those with already established carotid plaques, but not between VTE and novel plaque formation. The association between VTE and carotid plaque progression was not mediated by low-grade inflammation assessed by hs-CRP.

Ultrasound and Biochemical Diagnostic Tools for the Characterization of Vulnerable Carotid Atherosclerotic Plaque

Stroke is a leading cause of morbidity and mortality worldwide, and characterization of vulnerable carotid plaque remains the spearhead of scientific research. Plaque destabilization, the key factor that induces the series of events leading to the clinical symptoms of carotid artery disease, is a consequence of complex mechanical, structural and biochemical processes. Novel imaging and molecular markers have been studied as predictors of disease outcome with promising results. The aim of this review is to present the current state of research on the association between ultrasound-derived echogenicity indices and blood parameters indicative of carotid plaque stability and activity. Bibliographic research revealed that there are limited available data. Among the biomarkers studied, those related to oxidative stress, lipoproteins and diabetes/insulin resistance are associated with echolucent plaques, whereas adipokines are associated with echogenic plaques. Biomarkers of inflammation and coagulation have not exhibited any conclusive relationship with plaque echogenicity, and it is not possible to come to any conclusion regarding calcification-, apoptosis- and neo-angiogenesis-related parameters because of the extremely limited bibliographic data.

Red cell distribution width and carotid atherosclerosis progression. The Tromsø Study

Red cell distribution width (RDW), a measure of the size variability of circulating erythrocytes, is associated with cardiovascular morbidity and mortality. We aimed to investigate whether RDW was associated with progression of atherosclerotic plaques in subjects recruited from the general population. Baseline characteristics, including RDW, were collected from 4677 participants in the fourth survey of the Tromsø Study conducted in 1994/95. Prevalence of carotid plaques and total plaque area (TPA) were assessed by ultrasonographic imaging at baseline and after seven years of follow-up. Generalised linear models were used to analyse change in TPA across tertiles of RDW. Change in TPA was significantly higher across tertiles of RDW in crude analysis and in multivariable analysis adjusted for cardiovascular risk factors. The mean change in TPA increased from 5.6 mm² (4.9-6.4) in tertile 1 (RDW ≤ 12.6 %) to 6.7 mm² (5.9-7.6) in tertile 3 (RDW ≥ 13.3) in multivariable analysis adjusted for body mass index, total cholesterol, HDL cholesterol, systolic blood pressure, self-reported diabetes, smoking status, platelet count, white blood cell count, and hs-CRP levels (p for trend 0.003). A 1 % increase in RDW was associated with 0.6 mm² (0.1-1.2) increase in TPA in multivariable analysis (p=0.03). RDW was associated with progression of atherosclerosis after adjustments for traditional atherosclerotic risk factors. Our findings suggest that the link between RDW and cardiovascular morbidity and mortality may be explained by atherosclerosis.

Evaluation of serum 25-hydroxyvitamin d as a predictor of carotid intima-media thickness and carotid total plaque area in nonsmokers: the tromsø study

Objective. Altered calcium homeostasis has been linked to increased intima-media thickness (IMT) and plaques. We aimed to investigate whether serum 25-hydroxyvitamin D (25(OH)D) and serum calcium are associated with IMT and plaques in nonsmoking population. Methods. Ultrasound of the right carotid artery with the measurements of IMT and plaques was performed in 4194 nonsmoking subjects with available measurements of serum 25(OH)D and total calcium. Linear regression was applied to study the linear relationships between variables. Multinomial logistic regression was used to evaluate predictors of increased IMT and total plaque area (TPA), adjusted for age, body mass index, systolic blood pressure, and total cholesterol. Results. There was no significant linear relationship between mean IMT, TPA, and either serum 25(OH)D or total serum calcium. One SD increase in serum 25(OH)D was independently associated with increased odds of being in the highest quartile of IMT in men (OR 1.30, 95% CI 1.12, 1.51). In women, 1 SD increase in serum 25(OH)D was independently associated with increased risk of being in the upper tertile of TPA (OR 1.15, 95% CI 1.01, 1.33). Conclusions. Impaired calcium homeostasis has no consistent association with mean IMT and TPA; however, increased serum 25(OH)D may predict subclinical atherosclerosis in nonsmokers.

The echogenicity of the intima-media complex in the common carotid artery is related to insulin resistance measured by the hyperinsulinemic clamp in elderly men

The echogenicity of the intima-media complex (IM-GSM) has recently been shown to be related to the echogenicity in carotid artery plaque and to predict cardiovascular (CV) mortality. The present study aims to evaluate the relationship between metabolic CV risk factors, with special emphasis on insulin resistance, and IM-GSM in the carotid artery. Carotid artery ultrasound with grey-scale median analysis of the intima-media complex, IM-GSM, was performed in a population sample of 480 men aged 75 years. In these subjects, a euglycemic hyperinsulinemic clamp to investigate insulin resistance was performed together with measurements of conventional CV risk factors at the age of 70. The metabolic syndrome (MetS) was defined by the NCEP/ATPIII-criteria. In univariate analysis, IM-GSM in the common carotid artery was inversely correlated with the intima-media thickness (IMT), body mass index (BMI), waist/hip ratio, fasting glucose, serum triglycerides, low HDL cholesterol and insulin resistance at the clamp (r = -0·24, P<0·001). In multiple regression analysis, only insulin resistance at the clamp and BMI were independently related to IM-GSM. Subjects with the MetS (22%) showed a reduced IM-GSM when compared to those without (64 ± 20 SD versus 68 ± 19, P<0·05). Because the echogenicity of the intima-media complex in the carotid artery is related to obesity and insulin resistance at clamp independently of IMT, this new vascular characteristic would serve as a marker of vascular alterations induced by insulin resistance and the MetS and has the advantage to be obtainable in almost all subjects.

The metabolic syndrome and progression of carotid atherosclerosis over 13 years. The Tromsø study

Background

The metabolic syndrome (MetS) is associated with increased risk of cardiovascular disease. In this study, we examine if metabolic syndrome predicts progression of atherosclerosis over 13 years.

Methods

Participants were 1442 men and 1532 women in the population-based Tromsø Study who underwent carotid ultrasound examinations at baseline in the 4^th (1994–5) and at follow-up in the 6^th survey (2007–8). Of these, 278 men and 273 women fulfilled the criteria for the MetS, defined according to a modified version of the National Cholesterol Education Program Adult Treatment Panel III (NCEP, ATPIII). Carotid atherosclerosis was assessed as total plaque area (TPA) and mean intima-media thickness (IMT) at follow-up and as change in IMT and TPA from baseline to follow-up. Associations between MetS and its components and carotid atherosclerosis were assessed in linear regression models adjusted for age, total cholesterol and daily smoking, stratified by sex.

Results

IMT and TPA levels at follow-up (p < 0.0001) and progression of TPA (p = 0.02) were higher in the MetS group compared to the non-MetS group. In stepwise multivariable models, MetS was associated with TPA (β = 0.372 mm², p = 0.009) and IMT (β = 0.051 mm, p < 0.0001) in men, and with IMT (β = 0.045 mm, p = 0.001) in women after 13 years of follow-up, but not with progression of IMT or TPA. In analyses stratified by age, MetS predicted progression of IMT (β = 0.043 mm, p = 0.046) and TPA (β = 1.02 mm^2, p = 0.002) in men below 50 years of age. Hypertension was predictive of follow-up TPA and IMT in both genders and of progression of TPA in women. Impaired glucose tolerance was associated with follow up levels of IMT and TPA as well as progression in IMT in men. None of the other components of MetS were associated with progression of atherosclerosis.

Conclusions

Subjects with MetS had higher levels of IMT and TPA at follow up than those without MetS. Mets predicted progression of IMT and TPA in those below 50 years of age, but not in other age groups, indicating that MetS may be involved in the initiation of the atherosclerotic process.

Carotid artery plaque progression and cognitive decline: the Tromsø Study 1994-2008

BACKGROUND

Carotid atherosclerosis is a risk factor for stroke and cognitive decline, but knowledge on how progression of carotid atherosclerosis affects cognitive function in stroke-free individuals is scarce.

METHODS

In the population-based Tromsø study, we calculated the change in ultrasound-assessed carotid plaque number and total plaque area from baseline (survey 4) to follow-up 7 years later (survey 5) in 4274 middle-aged stroke-free subjects. Cognitive function was assessed at follow-up by the verbal memory test, the digit-symbol coding test, and the tapping test and repeated after an additional 6 years in a subgroup of 2042 subjects (survey 6). Associations between the average of survey 4 and survey 5 plaque scores and the progression of plaque scores and cognitive test scores were assessed in regression analyses adjusted for baseline age, sex, education, depression, and cardiovascular risk factors.

RESULTS

Progression of total plaque area was associated with lower scores in the digit-symbol coding test (multivariable adjusted standardized β, -0.03; 95% CI, -0.05 to -0.00; P = 0.04) and the tapping test (β, -0.03; 95% CI, -0.06 to -0.00; P = 0.03). Similar results were seen for progression of plaque number. The average plaque scores were associated with lower scores in all cognitive tests (P-values ≤ 0.01). No association was found between plaque scores and cognitive decline.

CONCLUSIONS

The average plaque scores were associated with lower scores in all cognitive tests. Progression of plaque scores was associated with lower scores in the digit-symbol coding test and the tapping test, but not with the verbal memory test or with cognitive decline.

Recurrence and long-term maternal health risks of hypertensive disorders of pregnancy: a population-based study

OBJECTIVE

The purpose of this study was to investigate the recurrence risk of hypertensive disorders in subsequent pregnancies and to explore the associations among hypertensive disorders of pregnancy and maternal cardiovascular risk factor profile and the development of cardiovascular diseases later in life.

STUDY DESIGN

We used population-based, cross-sectional data from the fourth survey of the Tromsø Study.

RESULTS

Preeclampsia in the first pregnancy increased the risk of recurrence in later pregnancies (relative risk, 6.6; 95% confidence interval, 5.5-7.9) compared with a normotensive first pregnancy. Women with a history of preeclampsia or nonproteinuric hypertension had an unfavorable cardiovascular risk profile. Hypertension was prevalent in 25% and 28% of the women, respectively. The carotid artery intima-media thickness and total carotid plaque area were significantly larger in women with previous preeclampsia.

CONCLUSION

A strong association between hypertensive disorders of pregnancy and an increased risk of atherosclerosis and cardiovascular diseases was demonstrated by the assessment of risk factors that can be potentially modified.

Carotid atherosclerosis predicts lower cognitive test results: a 7-year follow-up study of 4,371 stroke-free subjects - the Tromsø study

BACKGROUND

Carotid artery atherosclerosis is a major risk factor for stroke and subsequent cognitive impairment. Prospective population studies have shown associations between carotid intima-media thickness (IMT) and stenosis and cognitive decline and dementia in elderly stroke-free persons, whereas results in the middle-aged are conflicting.

METHODS

In this prospective population-based study, 4,371 stroke-free middle-aged participants underwent carotid ultrasound examination and assessment of vascular risk factors at baseline and were tested for cognitive function 7 years later. Associations between IMT, number of plaques and total plaque area and cognitive test scores on verbal memory test, digit symbol-coding test and tapping test were assessed in linear regression models.

RESULTS

In the multivariable analyses adjusted for sex, age, education, depression and vascular risk factors, the presence of plaques was significantly associated with lower test scores on the verbal memory test (p = 0.01) and on the digit symbol-coding test (p = 0.03). The number of plaques (p = 0.01) and the total plaque area (p = 0.02) were associated with lower scores on the verbal memory test. No significant association was seen between common carotid artery IMT and cognitive test scores. The tapping test was not associated with the carotid ultrasound variables.

CONCLUSIONS

In this middle-aged general population, subclinical carotid atherosclerosis measured as the presence of plaques, number of plaques and total plaque area were independent long-term predictors of lower cognitive test scores.

Subclinical carotid atherosclerosis and cognitive function

Carotid artery atherosclerosis is a major risk factor for stroke and subsequent cognitive impairment. Recent studies indicate that carotid atherosclerosis without clinical stroke may also be an independent risk factor for cognitive decline and dementia. Ultrasonography is an easily assessable and non-invasive method to measure different stages of the carotid artery atherosclerotic process and is widely used in clinical assessment as well as in epidemiological and clinical research. We give a brief review of studies that have investigated degrees of the subclinical atherosclerosis in the carotid arteries in relation to cognitive function and dementia, and we discuss several possible mechanisms that could explain the association between atherosclerosis and cognitive impairment.

Effect of computer monitor brightness on visual (subjective) carotid plaque characterization

PURPOSE

Visual carotid plaque classification on duplex imaging is moderately reproducible, and, although the literature is controversial, research to analyze and overcome this problem remains scarce. The aim of this study was to assess the effect of computer screen brightness on the intraobserver variation of visual plaque classification.

METHODS

One hundred asymptomatic noncalcified carotid plaques causing carotid stenosis >40% on duplex scanning, in 84 patients, were transferred to a personal computer, normalized, and classified into four groups of increasing echogenicity (types 1-4) at 50% and 100% of maximum monitor brightness settings. Baseline intraobserver variability of visual plaque classification at maximum brightness was also assessed.

RESULTS

Baseline intraobserver variability was moderate (Cohen's Kappa value 0.59, p < 0.001). Reduction in monitor brightness caused a systemic shift in echogenicity, with 51% of the type 2-4 plaques being classified as more echolucent. Likewise, Cohen's Kappa value decreased to 0.37, indicating poor agreement between the two classification rounds.

CONCLUSION

Reduction in computer screen brightness deteriorates the intraobserver variation of visual plaque classification. This finding could explain some of the discrepancy in reproducibility results reported and should be taken into account when using visual characterization methods.

Modern ultrasound methods and atherosclerosis assessment in patients with familial hypercholesterolemia

Familial hypercholesterolemia (FHCH) is characterised by early atherosclerosis development and its fast progression. The prevalence of FHCH inRussiahas been increasing, therefore, it is important to evaluate the potential of various methods for atherosclerosis diagnostics. Arterial ultrasound is an informative, accessible, and safe method for evaluating atherosclerotic vascular changes. The modern ultrasound methods allow describing vascular wall status in detail, including qualitative and quantitative characteristics of its structure and function. At the same time, most ultrasound characteristics of arterial wall are used in research settings or are under development, and not implemented into clinical practice. The most promising parameters, applicable for clinical use in FHCH patients, simultaneously describe atherosclerosis severity and its localization, such as total plaque height, ankle-brachial index, and plaque number.

Assessment of deep venous thrombosis by grayscale median analysis of ultrasound images

AIM

This study aimed to determine whether grayscale median (GSM) ultrasound (US) analysis could differentiate acute from subacute femoropopliteal deep venous thrombosis (DVT) classified based on (a) the time of symptoms onset and (b) sonographers' evaluation of US images.

METHODS

Patients who had US because of suspected DVT were included. Patients with history of previous DVT, with normal US results or US with findings of isolated calf thrombosis were excluded. A total of 128 venous segments of 63 patients were analyzed. Thrombosed veins and adjacent arteries images were recorded. Thrombi GSM were calculated. Grayscale median was compared with (a) the time of symptoms onset and (b) US image thrombi classification as acute or subacute done by 2 sonographers blinded to patient information. Statistical analysis included GSM Pearson intraobserver variability and t test comparisons of GSM means for (a) short versus long onset periods and (b) acute versus subacute US class, χ comparison between onset history and US class, creation of GSM accuracy, predictive values, and sensitivity curves for acute versus subacute DVT.

RESULTS

Intraobserver variability correlation varied between 0.92 and 0.95. Thrombus mean GSM was 23 ± 12 versus 31 ± 16 if symptoms onset was shorter or longer than 2 weeks (P = 0.004). Mean GSM was 20 ± 11 versus 35 ± 14 for acute versus subacute thrombi (P < 0.001). Acute thrombi correlated with onset shorter than 2 weeks (P < 0.001). Grayscale median less than 13, equal to 22, or 33 or less had 85% positive predictive value (17/20), 77% accuracy (98/128), and 90% sensitivity (53/59) to differentiate acute from subacute thrombi.

CONCLUSIONS

Grayscale median of US images documenting femoropopliteal DVT correlated with (a) the time between symptoms onset and US examination and (b) the sonographers' interpretation of acute versus subacute thrombosis.

Carotid plaque area and intima-media thickness in prediction of first-ever ischemic stroke: a 10-year follow-up of 6584 men and women: the Tromsø Study

BACKGROUND AND PURPOSE

Carotid plaque and intima-media thickness (IMT) are recognized as risk factors for ischemic stroke, but their predictive value has been debated and varies between studies. The purpose of this longitudinal population-based study was to assess the risk of ischemic stroke associated with plaque area and IMT in the carotid artery.

METHODS

IMT and total plaque area in the right carotid artery were measured with ultrasound in 3240 men and 3344 women aged 25 to 84 years who participated in a population health study in 1994 to 1995. First-ever ischemic strokes were identified through linkage to hospital and national diagnosis registries, with follow-up until December 31, 2005.

RESULTS

Incident ischemic strokes occurred in 7.3% (n=235) of men and 4.8% (n=162) of women. The hazard ratio for 1 SD increase in square-root-transformed plaque area was 1.23 (95% CI, 1.09-1.38; P=0.0009) in men and 1.19 (95% CI, 1.01-1.41; P=0.04) in women when adjusted for other cardiovascular risk factors. The multivariable-adjusted hazard ratio in the highest quartile of plaque area versus no plaque was 1.73 (95% CI, 1.19-2.52; P=0.004) in men and 1.62 (95% CI, 1.04-2.53; P=0.03) in women. The multivariable-adjusted hazard ratio for 1 SD increase in IMT was 1.08 (95% CI, 0.95-1.22; P=0.2) in men and 1.24 (95% CI, 1.05-1.48; P=0.01) in women. There were no differences in stroke risk across quartiles of IMT in multivariable analysis.

CONCLUSIONS

In the present study, total plaque area appears to be a stronger predictor than IMT for first-ever ischemic stroke.

18FDG PET and ultrasound echolucency in carotid artery plaques

OBJECTIVES

The objective was to evaluate inflammation in echolucent carotid artery plaques.

BACKGROUND

Ultrasound echolucency of carotid artery plaques has been proven to differentiate patients at high risk of stroke. On the other hand, positron emission tomography (PET) of plaques with the use of [(18)F]-fluorodeoxyglucose (FDG) identifies highly inflamed plaques, and the combination of molecular imaging and morphology could improve identification of vulnerable plaques.

METHODS

A total of 33 patients with cerebrovascular symptoms and carotid artery plaques were included prospectively for ultrasound and PET imaging. Plaque standardized gray scale medians (GSM) were measured in longitudinal ultrasound images to quantitate echolucency, and GSM values were compared with FDG PET uptake quantified by maximum standardized uptake values (SUV). Symptomatic plaques were compared with contralateral carotid artery plaques considered asymptomatic, and in 17 symptomatic patients, endarterectomized plaque specimens were analyzed for CD68 expression.

RESULTS

There was a negative correlation between GSM and FDG SUV (r = -0.56, p < 0.01). Whereas echo-rich plaques tended to show low FDG uptake, echolucent plaques ranged from high to low inflammatory activity, as depicted with PET. Quantitative FDG SUV differentiated asymptomatic from symptomatic plaques, whereas GSM values did not. There was a positive correlation between CD68 expression and FDG uptake (r = 0.50, p = 0.04).

CONCLUSIONS

Our results substantiate previous findings of an association between plaque FDG uptake and inflammation. Echolucent plaques exhibit a wide range of inflammatory activity, whereas echorich plaques show little inflammation. FDG PET may be useful for further stratification of echolucent plaques being either active (vulnerable) or inactive.

Serum osteoprotegerin, sRANKL and carotid plaque formation and growth in a general population--the Tromsø study

SUMMARY BACKGROUND

Intervention studies in animal models suggest that osteoprotegerin (OPG) functions as an inhibitor or marker of atherosclerosis, whereas one prospective epidemiological study in humans indicated that OPG was an independent risk factor for progression of atherosclerosis.

OBJECTIVE

To study the association between serum levels of OPG, soluble RANK ligand (sRANKL) and carotid artery plaque formation and plaque growth.

PATIENTS/METHODS

The prevalence of carotid plaque and plaque area were assessed by ultrasonographic imaging at baseline and after 7 years follow-up in 2191 men and 2329 women who participated in a population-based study.

RESULTS

OPG was significantly associated with atherosclerotic plaque burden and cardiovascular risk factors such as age, body mass index, blood pressure, total cholesterol, HDL cholesterol, HbA1c and fibrinogen at baseline, but not with sRANKL. In subjects without plaque at baseline, OPG predicted plaque formation in crude analysis in both women and men, but not after adjustment for age and other atherosclerotic risk factors. OPG predicted plaque growth in women (+1.8 mm(2), 0.6-3.0) (mean, 95% CI) per 1 SD increase in OPG (P = 0.003), whereas no associations were demonstrated in men (0.1 mm(2) (-1.3-1.4), P = 0.93). Soluble RANKL did not predict plaque formation or plaque growth.

CONCLUSIONS

OPG was an independent predictor of plaque growth in women, but not in men, suggesting gender-specific actions of OPG in plaque growth. OPG was not associated with novel plaque formation.

A review of noninvasive ultrasound image processing methods in the analysis of carotid plaque morphology for the assessment of stroke risk

Noninvasive ultrasound imaging of carotid plaques allows for the development of plaque-image analysis methods associated with the risk of stroke. This paper presents several plaque-image analysis methods that have been developed over the past years. The paper begins with a review of clinical methods for visual classification that have led to standardized methods for image acquisition, describes methods for image segmentation and denoising, and provides an overview of the several texture-feature extraction and classification methods that have been applied. We provide a summary of emerging trends in 3-D imaging methods and plaque-motion analysis. Finally, we provide a discussion of the emerging trends and future directions in our concluding remarks.

Atherosclerosis in abdominal aortic aneurysms: a causal event or a process running in parallel? The Tromsø study

OBJECTIVE

The pathogenesis of abdominal aortic aneurysm (AAA) formation is poorly understood. We investigated the relationship between carotid, femoral, and coronary atherosclerosis and abdominal aortic diameter, and whether atherosclerosis was a risk marker for AAA.

METHODS AND RESULTS

Ultrasound of the right carotid artery, the common femoral artery, and the abdominal aorta was performed in 6446 men and women from a general population. The burden of atherosclerosis was assessed as carotid total plaque area, common femoral lumen diameter, and self-reported coronary heart disease. An AAA was defined as maximal infrarenal aortic diameter > or =30 mm. No dose-response relationship was found between carotid atherosclerosis and abdominal aortic diameter <27 mm. However, significantly more atherosclerosis and coronary heart disease was found in aortic diameter > or =27 mm and in AAAs. The age- and sex-adjusted odds ratio (OR) (95% CI) for AAA in the top total plaque area quintile was 2.3 (1.5 to 3.4), as compared with subjects without plaques. The adjusted OR (95% CI) was 1.7 (1.1 to 2.6). No independent association was found between femoral lumen diameter and AAA.

CONCLUSIONS

The lack of a consistent dose-response relationship between atherosclerosis and abdominal aortic diameter suggests that atherosclerosis may not be a causal event in AAA but develops in parallel with or secondary to aneurismal dilatation.

Percentage white: a new feature for ultrasound classification of plaque echogenicity in carotid artery atherosclerosis

Atherosclerotic stenotic and nonstenotic plaques of the carotid artery with low echogenicity have been shown to be associated with cardiovascular disease. The aim was to develop a new method for semiautomated ultrasound image analysis to classify nonstenotic carotid plaques, evaluate cases with multiple plaques and examine the association between a new image analysis feature of echogenicity and predictors of cardiovascular disease. The new image analysis feature, percentage white (PW), represents the fraction of bright structures inside a plaque and is integrated in an objective semiautomated method to evaluate echogenicity (SAMEE) in carotid plaques. PW was constructed to take into account overall echogenicity of the image as well as noise surrounding the plaque. Consecutive ultrasound examinations of carotid plaques from a population-based screening of 64-year-old women with varying risk for cardiovascular disease were selected for the present project; 92 far-wall and 47 near-wall plaques were used as a training dataset to develop the SAMEE algorithm with visual classification according to Gray-Weale as reference; 273 plaques were used to validate the method. All plaques were included in an analysis relating predictors of cardiovascular to average PW in all plaques, PW in the biggest plaque and to the plaque with lowest PW in each subject, respectively. In the training dataset the intermethodological variability between SAMEE and visual classification showed a kappa of 0.78 and a sensitivity and specificity of 96% and 81%, respectively. In the validation set, SAMEE and visual classification showed a kappa of 0.77, a sensitivity of 96% and a specificity of 80%. The reproducibility of PW was high, evidenced by r = 0.96 and CV = 9.85% at repeated examinations. Average PW values were associated with several predictors of cardiovascular risk: lipoprotein (a), HbA1c, blood glucose, apolipoproteinB/apolipoproteinA-I; and associated negatively with the levels of adiponectin and apolipoprotein A-I. In conclusion, PW integrated within a SAMEE is a new feature for assessment of echogenicity in carotid plaques and shows excellent reproducibility and agreement with visual assessment.

Atheromatous plaque: quantitative analysis of the echogenicity of different layers

INTRODUCTION AND OBJECTIVES

Echographic studies of the composition of atheromatous plaque make use of the median gray level, which provides an overall measure of echogenicity. We propose adding an additional dimension to this approach by dividing the lesion into layers and generating a curve that shows the variation in echolucency with depth.

METHODS

Femoral and carotid plaque in asymptomatic patients was investigated using both the median gray level and new layer

METHODS

Interobserver variability was assessed for both

METHODS

Three risk factors were studied: age, gender and smoking status. Differences in echogenicity-depth curves between different groups were assessed using two-way ANOVA.

RESULTS

The two methods gave similar results for the mean echogenicity of carotid and femoral plaque. Echogenicity increased as a function of depth (r=0.96; P< .001). With the median gray level method, none of the risk factors produced a change in echogenicity. However, with the layer method, the echogenicity of femoral plaque was found to increase with age (P< .001), though gender had no effect. Moreover, the echogenicity of superficial layers was less in smokers than nonsmokers (P< .01). In carotid plaque, echogenicity increased with age (P< .01) and was higher in men (P< .01). The echogenicity of deep plaque was greater in smokers than nonsmokers (P< .05). The reproducibility of the two methods was similar.

CONCLUSIONS

The layer method was more effective than the median gray level method for identifying the effect of age, sex and smoking status on the echogenicity of atheromatous plaque.

Three-dimensional contrast-enhanced ultrasound of the liver: experience of 92 cases

Three-dimensional contrast-enhanced ultrasound (3D-CEUS) is a combination of three-dimensional ultrasound (3DUS) and contrast-enhanced ultrasound (CEUS). To evaluate the feasibility of 3D-CEUS in liver imaging, investigate possible influencing factors to its image quality, and evaluate the influence of 3D-CEUS to clinical outcome, low acoustic power (mechanical index, 0.08-0.13) 3D-CEUS was carried out in 102 focal liver lesions in 92 patients by using the LOGIQ 9 ultrasound scanner and a volume transducer (frequency range, 2-5 MHz; focusing ability, 2-25 cm in depth; azimuth aperture 5.9 cm). The lesions were classified into two groups: group 1 (n=51) for characterization and group 2 (n=51) for local treatment response evaluation. The factors that influenced the image quality of 3D-CEUS were analyzed. The image quality and usefulness of 3D-CEUS between the two groups were compared by using the chi(2)-test. The results showed that the lesion diameter, location, and scanning route had no significant influence on the image quality in both groups, whereas interfering factors damaged the image quality in group 1. In group 1, during arterial phase, high image quality was more frequently found in hyperenhanced and hypo- or non-enhanced lesions compared with isoenhanced lesions. In group 2, interfering factor and local treatment response had no obvious influence on the image quality. The visualization rate of high image quality was 94.1% (48/51) in group 2 vs. 72.6% (37/51) in group 1 (P=0.012). The investigators found that 3D-CEUS improved confidence but made no change in diagnosis in 19 (37.3%) of 51 lesions in group 1, whereas 41 (80.4%) of 51 lesions in group 2 (P=0.000). 3D-CEUS tends to obtain better image quality and lead to higher diagnostic confidence in the lesions for local treatment response evaluation, and perhaps is more useful in this aspect in future clinical settings.

Relation of common carotid artery lumen diameter to general arterial dilating diathesis and abdominal aortic aneurysms: the Tromsø Study

In a cross-sectional, population-based study in Tromsø, Norway, the authors investigated correlations between lumen diameter in the right common carotid artery (CCA) and the diameters of the femoral artery and abdominal aorta and whether CCA lumen diameter was a risk factor for abdominal aortic aneurysm (AAA). Ultrasonography was performed in 6,400 men and women aged 25-84 years during 1994-1995. An AAA was considered present if the aortic diameter at the level of renal arteries was greater than or equal to 35 mm, the infrarenal aortic diameter was greater than or equal to 5 mm larger than the diameter of the level of renal arteries, or a localized dilation of the aorta was present. CCA lumen diameter was positively correlated with abdominal aortic diameter (r = 0.3, P < 0.01) and femoral artery diameter (r = 0.2, P < 0.01). In a multivariable adjusted model, CCA lumen diameter was a significant predictor of AAA in both men and women (for the fifth quintile vs. the third, odds ratios were 1.9 (95% confidence interval: 1.2, 2.9) and 4.1 (95% confidence interval: 1.5, 10.8), respectively). Thus, CCA lumen diameter was positively correlated with femoral and abdominal aortic artery diameter and was an independent risk factor for AAA.

Prevalence of hypoechoic carotid plaques in coronary artery disease: relationship with coexistent peripheral arterial disease and leukocyte number

Abstract

In coronary artery disease (CAD), a concomitant peripheral arterial disease (PAD) entails a more severe coronary atherosclerosis. We hypothesized that the severity of carotid artery disease is greater in CAD+PAD than in CAD alone. In 90 CAD and 79 CAD+PAD patients, carotid plaque echolucency was measured by gray-scale median (GSM), and the degree of carotid stenosis by routine Doppler criteria. Plaques were absent in 20 (22.2%) CAD and 8 (10.1%) CAD+PAD patients ( p = 0.035), while the prevalence of carotid stenosis ≥ 50% was 16.7% and 25.3%, respectively ( p = 0.166). The GSM score was 45.1 [21.7–67.7] in CAD+PAD vs 60.1 [44.9–83.1] in CAD alone ( p < 0.001). Consistently, hypoechoic plaques (GSM < 25th percentile) were more common in CAD+PAD than in CAD patients (38.0% vs 11.4%, p < 0.001). On multivariate analysis, CAD+PAD was the only variable significantly associated with hypoechoic plaques (OR = 4.16, 95% CI 1.68–10.28). However, when the leukocyte count was added to the model, it showed the strongest association with hypoechoic plaques (OR = 6.70, 95% CI 2.13–21.10). In conclusion, compared with CAD alone patients, those with concomitant PAD showed a greater prevalence of plaques with characteristics of instability. Thus, our data suggest that in CAD+PAD, evaluation of carotid plaque echogenicity could contribute to improve clinical decision-making and differentiate treatments for individual patients.

Elevated levels of platelet microparticles in carotid atherosclerosis and during the postprandial state

BACKGROUND

Platelet microparticles (PMPs) possess proatherogenic and procoagulant properties which may play a role in atherogenesis and subsequent thromboembolic complications. The present study was conducted to investigate the possible relationship between carotid atherosclerosis and plasma concentrations of PMPs, and elucidate if plasma levels of PMPs were affected by postprandial hypertriglyceridemia.

METHODS AND RESULTS

Subjects with ultrasound-assessed carotid atherosclerotic plaques (echogenic; n=20 and echolucent; n=20), assessed by ultrasonography, and subjects without carotid plaques (n=20) were recruited from a population-based study and underwent a standard fat tolerance test. Subjects with carotid plaques had significantly higher levels of large PMPs than subjects without carotid atherosclerotic plaques (96.7+/-50.4 microg/l versus 56.1+/-34.9 microg/l), after adjustments for traditional cardiovascular risk factors and use cardiovascular drugs (p=0.021). Plasma PMPs were not associated with plaque echogenicity. Postprandial hypertriglyceridemia induced a similar increase in plasma PMPs within all groups. Significant correlations were found between an increase in plasma triglycerides and percent elevation in total PMPs (r=0.29, p<0.05) and large PMPs (r=0.34, p<0.01) in the postprandial phase.

CONCLUSIONS

Individuals with echogenic and echolucent carotid atherosclerotic plaques have statistically significant elevation of large plasma PMPs compared to age/sex-matched normal controls. Postprandial hypertriglyceridemia induces a significant, similar increase in plasma PMPs in individuals with and without carotid atherosclerotic plaques which could be of pathophysiological importance in atherogenesis.

Premature atherosclerosis in patients with xanthelasma

BACKGROUND

Only about half the patients with xanthelasma are hyperlipidemic. The clinical significance of xanthelasma as a marker of cardiovascular disease is not yet well defined.

OBJECTIVE

To determine the risk of cardiovascular disease in patients with normolipidemic and hyperlipidemic xanthelasma.

METHODS

Carotid ultrasonography (7 MHz using B-mode images, Advanced Technology Laboratories) was used to detect carotid plaques and measure the intima-media thickness (IMT) of the common carotid arteries. Seventeen patients with normolipidemic and hyperlipidemic xanthelasma were examined and compared with 21 age-matched normal subjects.

RESULTS

The risk of cardiovascular disease was significantly increased in patients with xanthelasma. Carotid plaques were more frequent in patients with xanthelasma than in controls (64.7% and 23.8%, respectively; P = 0.020), and IMT was significantly higher (mean +/- SD: 1.1 +/- 0.1 and 0.6 +/- 0.2 mm, respectively; P < 0.001). The difference of carotid IMT between normolipidemic xanthelasma and hyperlipidemic xanthelasma was not statistically different (mean +/- SD: 1.1 +/- 0.1 and 1.1 +/- 0.2 mm, respectively; P = 0.577).

CONCLUSION

Premature carotid atherosclerosis is observed in patients with normolipidemic and hyperlipidemic xanthelasma. Patients with xanthelasma should be considered to have an increased risk of cardiovascular disease independently to the level of plasma lipids. A larger number of patients is, however, needed to confirm this preliminary study.

The echogenecity of the intima–media complex in the common carotid artery is closely related to the echogenecity in plaques

OBJECTIVE

The echogenecity measured by ultrasound of atherosclerotic plaques is related to future cardiovascular events. The aim of the present study is to relate the grey scale median of the intima-media complex (IM-GSM) of the common carotid artery (CCA) to the echogenecity of carotid plaques.

MATERIAL AND RESULTS

In the Prospective Study of the Vasculature in Uppsala Seniors (PIVUS) study, a population-based study of 1016 subjects aged 70, carotid artery intima-media thickness (IMT) and IM-GSM were evaluated by ultrasound and computerized analysis. Also the occurrence of plaque and plaque GSM were measured. The echogenecity of the plaques was also visually estimated by the Gray-Weale classification. In subjects with a carotid plaque (n=582), IM-GSM in CCA was correlated to GSM in the plaque (r=0.60, p<0.0001) independently of plaque size and IMT. IM-GSM in CCA was also correlated to the visually estimated echogenecity (p<0.0001 for trend).

CONCLUSION

IM-GSM of the CCA is closely related to the echogenecity in overt carotid plaques, regardless if evaluated by the same computerized method or evaluated visually. This finding suggests that IM-GSM of CCA could be an important and easily measurable characteristic of the carotid artery wall that could be obtained in almost all subjects and not only those with an overt plaque.

Brachial artery intima-media thickness and echogenicity in relation to lipids and markers of oxidative stress in elderly subjects:--the prospective investigation of the vasculature in Uppsala Seniors (PIVUS) Study

The aim of the present study was to relate brachial artery intima-media thickness (IMT) and the grey scale median of the intima-media complex (IM-GSM) to traditional cardiovascular risk factors and markers of inflammation and oxidative stress. In the Prospective Study of the Vasculature in Uppsala Seniors (PIVUS) study, a population-based study of 1016 subjects aged 70, brachial artery IMT and IM-GSM, who were evaluated by ultrasound. Lipids, thirteen markers of inflammation and nine markers of oxidative stress were measured. The Framingham risk score was related to IMT (p < 0.0001), but not to the IM-GSM. In univariate analysis, HDL-cholesterol, serum triglycerides, fasting glucose, smoking, HOMA insulin resistance index and oxidized LDL levels were related to IMT. HDL and LDL-cholesterol, triglycerides, VCAM-1, e-selectin, leukocyte count, conjugated diens, baseline conjugated diens (BCD)-LDL, antibodies to oxLDL, the GSSG/GSH glutathione ratio and homocysteine were related to IM-GSM. In multiple regression models, HDL-cholesterol, fasting glucose and oxLDL levels were the independently related to IMT (p = 0.01-0.04), while serum triglycerides, BCD-LDL and the GSSG/GSH ratio were independently related to IM-GSM (p = 0.0001-0.004). In conclusion, in addition to traditional lipid variables, markers of oxidative stress were associated with both thickness and echogenicity of the brachial artery intima-media complex. Thus, both thickness and echogenicity of the brachial artery intima-media complex might be useful biomarkers in the future.

Carotid Atherosclerosis Is a Stronger Predictor of Myocardial Infarction in Women Than in Men

Background and Purpose— Ultrasound of carotid arteries provides measures of intima media thickness (IMT) and plaque, both widely used as surrogate measures of cardiovascular disease. Although IMT and plaques are highly intercorrelated, the relationship between carotid plaque and IMT and cardiovascular disease has been conflicting. In this prospective, population-based study, we measured carotid IMT, total plaque area, and plaque echogenicity as predictors for first-ever myocardial infarction (MI).

Methods— IMT, total plaque area, and plaque echogenicity were measured in 6226 men and women aged 25 to 84 years with no previous MI. The subjects were followed for 6 years and incident MI was registered.

Results— During follow-up, MI occurred in 6.6% of men and 3.0% of women. The adjusted relative risk (RR; 95% CI) between the highest plaque area tertile versus no plaque was 1.56 (1.04 to 2.36) in men and 3.95 (2.16 to 7.19) in women. In women, there was a significant trend toward a higher MI risk with more echolucent plaque. The adjusted RR (95% CI) in the highest versus lowest IMT quartile was 1.73 (0.98 to 3.06) in men and 2.86 (1.07 to 7.65) in women. When we excluded bulb IMT from analyses, IMT did not predict MI in either sex.

Conclusions— In a general population, carotid plaque area was a stronger predictor of first-ever MI than was IMT. Carotid atherosclerosis was a stronger risk factor for MI in women than in men. In women, the risk of MI increased with plaque echolucency.

Proinsulin:insulin and insulin:glucose ratios as predictors of carotid plaque growth: a population-based 7 year follow-up of the Tromsø Study

AIMS/HYPOTHESIS

Proinsulin is increased in persons at cardiovascular risk. Increased secretion of proinsulin relative to insulin has been suggested as a sign of defective conversion of proinsulin to insulin and C-peptide and is associated with beta cell dysfunction. It has also been suggested that proinsulin has more of a pro-atherogenic effect than insulin, the levels of which are also increased in the insulin resistance state. In this prospective population-based study, we examined whether the proinsulin:insulin ratio (PIR) or insulin:glucose ratio (IGR, an insulin resistance surrogate) predicted carotid plaque size in nondiabetic participants.

MATERIALS AND METHODS

The study included 1,859 men and 1,998 women aged 25-82 years from the Tromsø Study, who were examined with B-mode high resolution ultrasound at baseline in 1994-1995 and at follow-up in 2001-2002. All images were computer processed to yield mm(2) measures of plaque. Proinsulin and insulin were measured at baseline. All analyses were stratified for sex.

RESULTS

After adjusting for age, baseline plaque area, BMI, cholesterol, HDL-cholesterol, HbA(1c), IGR, albumin:creatinine ratio, fibrinogen, BP and lifestyle factors (tobacco smoking, alcohol consumption, physical activity), PIR was significantly associated with plaque size at follow-up in women but not men. For each SD in the PIR in women, the mean plaque area increased by 0.97 mm(2) (95% CI 0.44-1.50). IGR was not associated with carotid plaque size.

CONCLUSIONS/INTERPRETATION

The PIR is associated with progressive carotid artery plaque size in women.