B-mode ultrasound assessment of pravastatin treatment effect on carotid and femoral artery walls and its correlations with coronary arteriographic findings: a report of the Regression Growth Evaluation Statin Study (REGRESS)

OBJECTIVES: In this B-mode ultrasound study we assessed pravastatin treatment effects on carotid and femoral artery walls and investigated the correlations between the state and evolution of peripheral and coronary atherosclerosis. BACKGROUND: The Regression Growth Evaluation Statin Study (REGRESS) was an 11-center, 2-year, double-blind, placebo-controlled, prospective study of 885 men with coronary artery disease (CAD) (total cholesterol 4 to 8 mmol/liter). The study primarily investigated pravastatin treatment effects on the coronary lumen. This report focuses on the 255 patients who participated in the REGRESS ultrasound study. METHODS: Carotid and femoral artery walls were imaged at baseline and at 6, 12, 18 and 24 months. Pravastatin treatment effect was defined as the difference in progression of the combined intima-media thicknesses (IMT) between treatment groups. RESULTS: Pravastatin treatment effects were highly significant (combined IMT: p = 0.0085; combined far wall IMT: p < 0.0001; common femoral artery far wall IMT: p = 0.004). Correlations between the IMTs of the arterial wall segments ranged from -0.17 to 0.81. Baseline correlations between IMT and percent coronary lumen stenoses ranged from 0.23 to 0.36. Baseline IMT correlated with the mean coronary segment diameter (r = -0.32, p = 0.001) and minimal coronary obstruction diameter (r = -0.27, p = 0.005). There were no individual correlations between IMT and coronary lumen variables (p > 0.30). CONCLUSIONS: Pravastatin treatment effects on carotid and femoral artery walls were observed. B-mode ultrasound imaging studies of peripheral arterial walls could not describe the state and evolution of the coronary lumen in the individual patient, but proved to be a highly suitable tool for the assessment of antiatherosclerotic properties of agents.     

Effect of ibudilast on microcirculation thrombosis in rat inner ear

Arterial wall thickening may be quantitatively assessed by measuring the intima-media thickness (IMT) with high resolution ultrasound. Previous studies have shown a good inter/intraobserver variability of IMT measurements in the common carotid. In this study we evaluated the inter/intraobserver variability of IMT measurements in 10 randomly selected asymptomatic subjects (age 55.4 +/- 6). Two carotids and two femorals were studied in each subject. IMT for each patient was the average of five IMT measurements at the artery bifurcation. Three observers repeated the scanning and the measurements twice with no knowledge of the previous readings. The between observer coefficient of variation (CV) was 8.45%; the intraobserver CV (mean of carotids and femorals) varied from 4.4 to 5.1% for the three observers who measured IMT three times. The mean absolute difference between the first and the third measurement was 0.0738 mm. In conclusion IMT measurement variability is mostly due to differences between observers. The intraobserver variability is very small. IMT measurements at the carotid and femoral bifurcations have a low variability and are a good expression of atherosclerosis as they consider early lesions at the bifurcation level which may not be observed in the common carotid.     

Relations of intimal-medial thickness among sites within the carotid artery as evaluated by B-mode ultrasound. ARIC Investigators. Atherosclerosis Risk in Communities

BACKGROUND AND PURPOSE: B-mode ultrasound is a widely used technique for the clinical and epidemiological assessment of carotid atherosclerosis. This article describes the relation between arterial intimal-medial thickness (IMT) at different sites within the extracranial carotid artery. METHODS: IMT was measured by B-mode real-time ultrasound as an index of atherosclerotic involvement in the extracranial carotid arteries as part of the population-based Atherosclerosis Risk in Communities (ARIC) study. The relation between IMT at different sites was described by correlation coefficients and percentile regression techniques based on between 4034 and 9386 pairs of measurements (variation in sample size depending on the paired sites). RESULTS: Increased IMT at one site was associated with increased IMT at other sites. The correlation between right and left IMT at the same anatomic location in the carotid artery ranged from .34 to .49; the correlation at different anatomic locations in the carotid artery on the same side ranged from .25 to .43. The distribution of IMT, described by the percentiles of IMT at the inference site as a function of IMT at the index site, showed constricted percentiles of IMT at the inference site for small IMT at the index site and an increase in the spread of percentiles with increasing IMT. CONCLUSIONS: Although increased carotid IMT at one site is positively associated with thickened walls at other carotid sites, the ability to accurately predict wall thickness at a site given the wall thickness at other sites is modest. The general association between sites supports the systemic nature of atherosclerosis, while the lack of tight agreement between sites supports the focal nature of the atherosclerotic process.     

Automated intima-media thickness: the Los Angeles Atherosclerosis Study

Common carotid artery (CCA) intima-media thickness (IMT) from B-mode ultrasound is a widely used measure of early atherosclerosis. This study evaluated within- and between-sonographer reproducibility of automated edge-tracking IMT using a low-cost mobile scanner. B-mode images of the left and right CCA were acquired on two occasions (interval of 2-14 days) by two sonographers for 38 subjects, aged 31-75 y. Reproduciblity error was measured as the mean absolute difference (MAD+/-SEM) and the standard deviation of differences (SDdelta) between repeated measurements. Within-sonographer (MAD=0.027+/-0.006 mm; SDdelta=0.044 mm) and between-sonographer errors (MAD=0.041+/-0.008 mm; SDdelta=0.064) in IMT (mean=0.74, SD=0.14) of a single artery were small compared to those of other protocols. Combined averaging across both body positions and arteries reduced intersonographer MAD by 47% (MAD=0.022+/-0.003 mm; SDdelta=0.029 mm). These data demonstrate that the proposed IMT protocol reduces reproducibility error by more than 50% relative to several protocols used in other major studies.     

Potent inhibitory effect of troglitazone on carotid arterial wall thickness in type 2 diabetes

There is increasing evidence that insulin resistance may be causally related to atherosclerosis. The measurement of common carotid arterial intimal and medial complex thickness (IMT) by B-mode ultrasound technique has been recognized as a powerful and non-invasive method to evaluate early atherosclerotic lesions. We investigated the effect of treatment with troglitazone, an insulin sensitizer, on IMT in a total of 135 Japanese subjects with type 2 diabetes. Troglitazone (400 mg daily) was administered for 6 months in 57 patients. Compared to control group (n = 78), the group given troglitazone showed a significant decrease in IMT as early as 3 months after the administration (IMT change: -0.080[SE 0.016] mm vs. control 0.027[SE 0.007] mm, P < 0.001). The decrease in IMT was also found after 6 months, although further decrease was not observed. Both HbA1c and postprandial serum triglycerides were decreased after troglitazone, but there was no statistically significant relation between a decrease in IMT and those in HbA1c or postprandial triglycerides. These findings indicate that troglitazone has a potent inhibitory effect on progression of early atherosclerotic lesions probably through the decreased insulin resistance in type 2 diabetes.     

Carotid atherosclerosis in adolescents and young adults with IDDM. Relation to urinary endothelin, albumin, free cortisol, and other factors

OBJECTIVE: To investigate 1) alterations of carotid intimal-plus-medial thickness (IMT) in subjects with IDDM and 2) the relation of IMT to indexes of diabetic angiopathy and to risk factors of atherosclerosis. RESEARCH DESIGN AND METHODS: IMT was assessed by ultrasound B-mode imaging in 39 subjects with IDDM (23 male, 16 female young adults aged 17.5 +/- 5.2 years, diabetes duration 8.8 +/- 5.9) and in 22 control subjects (healthy siblings of the IDDM subjects) of comparable age. Urinary endothelin (UET1) and urinary free cortisol (UFC) were determined by radioammunoassay (RIA), urinary albumin by nephelometry, HbA1c by high-performance liquid chromatography (HPLC), and plasma renin by immunoradiometric assay (IRMA). RESULTS: The IMT values were greater in IDDM subjects than in control subjects (0.49 +/- 0.1 mm, 0.44 +/- 0.09 mm, respectively; P = 0.048) and greater in IDDM male subjects than in control male subjects (0.52 +/- 0.09 and 0.44 +/- 0.06 mm, respectively; P = 0.015), with no difference between IDDM and control female subjects. The IMT values were greater in diabetic male subjects than in female subjects (0.52 +/- 0.09 and 0.45 +/- 0.1 mm, respectively; P = 0.017). In IDDM subjects, but not in control subjects, there was a positive correlation of IMT to urinary albumin (P = 0.008), systolic blood pressure (P = 0.023), UET1 (P = 0.016), UFC (P = 0.002), and BMI (P = 0.021). Multiple regression analysis demonstrated that in IDDM subjects the variable that interacts independently with IMT was the BMI (P = 0.001). CONCLUSIONS: IMT, an index of atherosclerosis (macroangiopathy), is increased in IDDM subjects quite early (already in adolescence), and it is positively related to urinary albumin, UET1, blood pressure, and UFC.     

Vascular and cardiac remodeling in world class professional cyclists

BACKGROUND: Numerous studies have demonstrated that left ventricular (LV) hypertrophy is often associated with conditioning. METHODS AND RESULTS: The aim of the study was to evaluate cardiac and carotid artery changes induced by professional cycling. We collected M-mode left ventricle and B-mode right common carotid artery data from 149 male professional cyclists before the 1995 "Tour de France" race and 52 male control subjects. LV mass indexed to body surface area in cyclists was double that in control subjects, with no overlap of 95% confidence intervals (cyclists 100.9 to 187 g/m2 and control subjects 51.8 to 96.3 g/m2). Both mean arterial diameter and mean arterial diastolic intima-media thickness (IMT) were 13% higher in cyclists than in control subjects, with overlap of 95% confidence intervals (for arterial IMT 0.45 to 0.65 mm in cyclists and 0.38 to 0.60 mm in control subjects). CONCLUSIONS: Our results suggest that intense cycling has an effect on the cardiovascular system, more pronounced on the left ventricle and less pronounced on large arteries. Nevertheless, athletic training should be considered as a potential determinant of carotid modification.     

Carotid and femoral artery wall thickness and stiffness in patients at risk for cardiovascular disease, with special emphasis on hyperhomocysteinemia

Recent developments in ultrasound technology enable the noninvasive measurement of structural and functional vessel wall changes. Until now, the effect of homocysteine on the arterial wall has remained unclear: reports on intima-media thickness (IMT) yield conflicting results, whereas data on vessel wall stiffness are lacking. Because several cardiovascular risk factors result in an increased IMT or stiffness, different groups at risk for atherosclerotic disease, with special emphasis on hyperhomocysteinemia, were studied. Nineteen patients homozygous and 14 subjects heterozygous for cystathionine beta-synthase (CBS) deficiency, 21 patients with familial hypercholesterolemia (FH), 15 patients with essential hypertension, 20 smokers, and 28 control subjects were studied. The IMT values (both right and left) of the common carotid artery (CCA), bulb (BUL), internal carotid artery (ICA), and common femoral artery (CFA) were measured in millimeters by high-resolution ultrasound (Biosound). The distensibility (DC, in 10(-3). kPa-1) and compliance (CC in mm2. kPa-1) coefficients of the CCA (right and left) and CFA (right) were determined by a wall track system (Pie Medical). The mean IMT of the posterior wall in the CCA was 0.70+/-0.09 mm in healthy controls. For patients with vascular disease, FH, and hypertension and in smokers, the mean CCA IMT was larger, whereas no major differences in IMT were observed in patients either homozygous or heterozygous for CBS deficiency. The DC and CC in the right CCA were 23.5+/-6.9 (10(-3). kPa-1) and 0.9+/-0.3 (mm2. kPa-1) in healthy subjects, slightly lower in patients homozygous for CBS deficiency, and clearly lower in patients with vascular disease, FH, and hypertension. No positive correlation was found between plasma homocysteine level and either IMT, CC, or DC. Because smoking was a confounder in each risk group, a stepwise regression analysis was carried out to assess the contribution of each risk factor on IMT and arterial wall stiffness. Age explained most of the variation in IMT of the CCA (coefficient of determination R2 of 0.34), whereas R2 values for serum low density lipoprotein cholesterol, smoking (pack-years), and systolic blood pressure were 0.08, 0.07, and 0.06, respectively. Homocysteine did not contribute to variation in IMT in both the CCA and CFA. Age and smoking contributed to the variation in IMT in the CFA. The variation in DC and CC in the right CCA and right CFA could in part be explained by age, low density lipoprotein cholesterol, and blood pressure. Plasma homocysteine concentration explained only a small proportion of the variation in DC in the CCA (R2=0.02) and in CC in the CFA (R2=0.04). In this study, no relationship was found between homocysteine level and the thickness of the arterial wall, with only a marginal influence on stiffness.     

George Lyman Duff Memorial Lecture. Arterial imaging and atherosclerosis reversal

This review explores evidence for the reversibility of atherosclerosis and augmentation of angiography with non-invasive arterial wall imaging. Meta-analysis from coronary angiographic trials demonstrates that regression and stabilization are 1.5 to 2 times more common in treated than placebo subjects, and progression is reduced by half in treated subjects. Odds ratios for clinical coronary events are significantly reduced with treatment. Lesion improvement occurs more readily in women than men and more so in women receiving concomitant estrogen replacement therapy. Lesions with > or = 50% diameter stenosis (%S) at baseline respond more readily to lipid lowering than those < 50% S, whereas reduction in coronary events is related to stabilization of lesions < 50% S. Lipoproteins have a differential effect on lesion progression according to lesion size, and triglyceride-rich lipoproteins play an important role in the progression of coronary artery lesions < 50% S. Improved therapeutic regimens to alter progression of atherosclerosis may require adjunctive therapy, such as with antioxidants or hormone replacement therapy, in concert with low-density lipoprotein cholesterol reduction to prevent new lesion formation or early lesion progression. Sequential coronary angiographic determination of progression evaluated by both quantitative coronary angiography and global change score, a visual assessment of overall lesion change, predicts clinical coronary events. Only inferences about the state of the arterial wall can be made from angiography, because it delineates only the lumen. Therapy testing and study of atherosclerosis progression can be improved with noninvasive B-mode ultrasonographic imaging of the distal common carotid artery far-wall intima-media thickness (IMT), a reliable measure of early preintrusive atherosclerosis. Measurement of common carotid IMT is useful for the study of coronary artery risk factors and can augment studies of coronary artery intrusive lesions, because it is associated with coronary artery disease. B-mode measurement of common carotid IMT has the potential of serving as a noninvasive surrogate end point for clinical coronary events. Screening for peripheral vessel changes indicative of high risk for coronary artery disease is possible and cost-effective with the noninvasive procedures now available.     

Determination of intima-media thickness of the carotid artery: influences of methods, proband and examination variables

AIM: Comparison of two different methods for the measurement of the common carotid artery intima-media thickness (IMT) regarding results and reproducibility, and investigation of the influence of the subjects' characteristics on the results. METHOD: 20 healthy subjects were studied (6 men, 14 women, mean age 27.4 +/- 4.4 years). B-Mode pictures were taken of the carotid arteries on both sides (longitudinal sections from ventral and lateral) and stored for measurement either in systole or in diastole. Maximum IMT was measured conventionally by manual setting of calipers (method 1), the mean IMT over a length of 1 cm was calculated from the area of the intima plus media by means of a computer (method 2). 10 subjects were studied twice for the evaluation of intra- and interobserver variability. RESULTS: Mean IMT was between 0.48 +/- 0.07 mm (method 1/observer 1) and 0.55 +/- 0.07 mm (method 2/observer 2). IMT values resulting from method 2 had a better correlation in repeated measurements (coefficient 0.84/0.93 for inter-/intraobserver comparison) than those resulting from method 1 (0.79/0.67). Age and height were significantly correlated with IMT (coefficients 0.53 and 0.52 for method 2), no correlation was found for body weight, BMI, sex or years of smoking. There was a significant inverse correlation between blood pressure and IMT (-0.21 to -0.32). CONCLUSION: In younger healthy subjects, the results of IMT measurement are influenced by age, height and actual blood pressure. The values resulting from both methods are comparable, whereas method 2 has a better reproducibility.     

Detection of the phosphorylcholine epitope in streptococci, Haemophilus and pathogenic Neisseriae by immunoblotting

Intimal-medial thickness (IMT) of the extracranial carotid arteries measured by B-mode ultrasonography has been used as a marker of systemic and coronary atherosclerosis. Previous studies have indicated that maximum and mean carotid IMT are significantly correlated with the extent and severity of coronary artery disease (CAD), but the clinical usefulness of these markers is limited because they are neither specific nor sensitive enough to identify patients with or without significant CAD. The correlation of a new IMT marker, variance of IMT, with coronary risk factors and coronary atherosclerosis was investigated in 200 patients who underwent carotid ultrasonography and coronary angiography. IMT was measured in 16 sites of the extracranial carotid arteries for the calculation of mean, maximum and variance of IMT. Univariate analysis showed that these three indexes were significantly correlated with age, serum lipoprotein (a) and hypertension. However, age was correlated weakly with variance of IMT. There were significant gender differences in the mean and maximum IMT but not in the variance. There were also significant correlations of mean IMT with smoking, and maximum and variance of IMT with high-density lipoprotein. Multiple logistic regression analysis in 100 age and sex matched patients indicated that the only significant predictor for CAD in this subgroup was variance of IMT (odds ratio = 1.6). These results indicated that each risk factor causes different morphologic manifestations in the carotid atherosclerotic lesion. Variance of IMT, which represents the irregularity of carotid IMT, was correlated well with CAD and appears to be useful for assessing systemic and coronary atherosclerosis.     

Effect of DMPPO, a phosphodiesterase type 5 inhibitor, on hypoxic pulmonary hypertension in rats

PURPOSE: The study was done to improve quantification of multiple arterial stenoses and to investigate a new imaging technique for lower limb arteries. Three-dimensional power Doppler angiography was used to quantify in vitro arterial stenoses. METHODS: We built two types of artery phantoms containing multiple stenoses. One used stenotic porcine arteries, and the other was designed to control the proximal and distal stenoses while we assessed central stenosis of a wall-less agar lumen. Three-dimensional power Doppler angiograms of the flow lumens were generated at different flow rates under steady and pulsatile flow conditions with a PowerPC 8500 computer-based three-dimensional ultrasound imaging system. This experimental system works off-line, performs three-dimensional acquisition, reconstruction, and display of ultrasound images. Images of flow lumens were compared with the measured B-mode images or the true geometry. RESULTS: This technique produces good three-dimensional angiographic images of the flow lumen, and multiple stenoses do not affect the diagnosis of arterial stenoses. With this technique, the average errors for estimating 80% and 50% area reduction stenoses were -10% and 4%, respectively. CONCLUSIONS: Three-dimensional power Doppler angiography has the potential to quantitatively grade multisegmental stenoses in lower limbs and generate a map for vasculature surgery planning.     

Reliability and validity studies of a new computer-assisted crossed-cylinder aberroscope

PURPOSE: We assessed the reliability and validity of a new computer-assisted crossed-cylinder aberroscope technique which measures the monochromatic optical aberrations of the human eye. METHODS: Intra-image variability, the variability occurring when the same image is repeatedly measured, and inter-image variability, the variability occurring when different images collected from the same eye are measured, were assessed using 10 repeated measures on each of 10 different subjects. We compared the measurements made using the computer-assisted technique with manual measurements made when a human operator performed all the aberroscope grid intersection location tasks. RESULTS: One-way repeated measures analyses of variance (ANOVA) on the inter-image and intra-image variability showed that the mean of the measurements made was statistically independent of the occasion on which a group of subjects was measured, and inter-image variability was larger than intra-image variability. A two-way repeated measures ANOVA comparing computer-assisted results with manual results showed that the means of the measurements made with the two methods are not statistically different from one another. The manual results showed greater variability than computer-assisted measurements. CONCLUSIONS: The technique is reliable and valid compared to earlier objective crossed-cylinder aberroscopic techniques.     

Potential advantage of flash echocardiography for digital subtraction of B-mode images acquired during myocardial contrast echocardiography

Optimal assessment of myocardial perfusion with contrast echocardiography by using B-mode imaging often requires image alignment and background subtraction, which are time consuming and need extensive expertise. Flash echocardiography is a new technique in which primary images are gated to the electrocardiogram and secondary images are obtained by transmitting ultrasound pulses in rapid succession after each primary image. Myocardial opacification is seen in the primary image and not in the secondary images because of ultrasound-induced bubble destruction. Because the interval between the primary and first few secondary images is very short, cardiac motion between these images should be minimal. Therefore we hypothesized that 1 or more secondary images could be subtracted from the primary image without the need for image alignment. The ability of ultrasound to destroy microbubbles was assessed by varying the sampling rate, line density, and mechanical index in 6 open-chest dogs. The degree of translation between images was quantified in the x and y directions with the use of computer cross-correlation. At sampling rates of 158 Hz or less and a mechanical index of more than 0.6, videointensity rapidly declined to baseline levels by 25 ms. Significant translation between images was noted only at intervals of more than 112 ms. It is concluded that flash echocardiography can be used for digital subtraction of baseline from contrast-enhanced B-mode images without image alignment. Background subtraction is therefore feasible on-line, potentially eliminating the need for off-line image processing in the future.     

Reproducibility of fat area measurements in young, non-obese subjects by computerized analysis of magnetic resonance images

OBJECTIVE: To assess reproducibility, expressed as both inter-observer variability and intra-observer variability, of fat area measurements on images obtained by magnetic resonance (MR); to compare variability between fat area measurements, calculated from a single image per body region and from the average fat area of three images, and to determine reproducibility of image acquisition at the abdominal level. SUBJECTS: Thirty young, non-obese subjects (reproducibility of image analysis) and nine young, non-obese subjects (reproducibility of image acquisition). METHODS: Three MR images at the level of the abdomen (in 30 subjects) and at the level of the hip and thigh (in 14 of them). Quantification of subcutaneous fat depots (abdomen, hip and thigh) and visceral fat depots using an image-analyzing computer program. Assessment of variability of image analysis for fat area measurements between two observers and within observers. Assessment of reproducibility of image acquisition at the abdominal level (in nine subjects). RESULTS: Subcutaneous fat areas in all body regions were quantified with coefficients of variation (CV) ranging from only 2.1%-4.9%. By contrast, visceral fat area measurements showed markedly higher CVs (range: 9.4%-17.6%). Moreover, relative variability was much larger in small visceral fat areas (CVs up to 25.6%). The majority of CVs, calculated for intra-observer variability and calculated from the average fat area measurements of three images, was lower than calculated for inter-observer variability and for one single image, respectively. In particular, for the visceral fat depot, this reduction in variability had practical consequences for the number of subjects required for a study. Variation of repeated image acquisition was in the same range as variation of repeated measurements on the same image. CONCLUSION: One image per body site is sufficient to obtain a reliable estimate of subcutaneous fat depots. For estimations of the visceral fat depot, the average area measurements of three images reduces variability and increases statistical power. The availability of one single experienced observer during a study adds to accuracy.     

Practical aspects of faculty practice. A model for excellence

The aim of the study was to determine the intrasubject variability of the pressure-transmission ratio (PTR) with various cough intensities in subjects with genuine stress incontinence. Thirty-six patients with genuine stress incontinence underwent multichannel urodynamics and had a series of pressure-transmission ratios (PTRs) determined with the urethral transducer placed at the point of the maximal closure pressure. Patients were asked to cough with increasing intensities and three to four different cough-induced PTRs were recorded for each subject. The data were analysed using regression analysis, repeated measures analysis of variance and comparison of variance. The PTRs showed a high degree of variability within subjects. The mean within subject standard deviation was 18.5%. The effect of parity, maximal urethral closure pressure and age were insignificant on the variability. Cough intensities of greater than 90 cmH2O have a lesser degree of variability. The mean PTR across all cough intensities was fairly constant in the 82%-87% range. It was concluded that the PTR in an individual has a high degree of variability independent of cough intensity, and cannot be relied upon as a diagnostic measure in subjects with genuine stress incontinence. However, the PTR for the population as a whole was consistent across all cough intensities.     

Association of coronary heart disease incidence with carotid arterial wall thickness and major risk factors: the Atherosclerosis Risk in Communities (ARIC) Study, 1987-1993

Few studies have determined whether greater carotid artery intima-media thickness (IMT) in asymptomatic individuals is associated prospectively with increased risk of coronary heart disease (CHD). In the Atherosclerosis Risk in Communities Study, carotid IMT, an index of generalized atherosclerosis, was defined as the mean of IMT measurements at six sites of the carotid arteries using B-mode ultrasound. The authors assessed its relation to CHD incidence over 4-7 years of follow-up (1987-1993) in four US communities (Forsyth County, North Carolina; Jackson, Mississippi; Minneapolis, Minnesota; and Washington County, Maryland) from samples of 7,289 women and 5,552 men aged 45-64 years who were free of clinical CHD at baseline. There were 96 incident events for women and 194 for men. In sex-specific Cox proportional hazards models adjusted only for age, race, and center, the hazard rate ratio comparing extreme mean IMT (> or = 1 mm) to not extreme (< 1 mm) was 5.07 for women (95% confidence interval 3.08-8.36) and 1.85 for men (95% confidence interval 1.28-2.69). The relation was graded (monotonic), and models with cubic splines indicated significant nonlinearity. The strength of the association was reduced by including major CHD risk factors, but remained elevated at higher IMT. Up to 1 mm mean IMT, women had lower adjusted annual event rates than did men, but above 1 mm their event rate was closer to that of men. Thus, mean carotid IMT is a noninvasive predictor of future CHD incidence.     

Increased common carotid intima-media thickness. Adaptive response or a reflection of atherosclerosis? Findings from the Rotterdam Study

BACKGROUND AND PURPOSE: Carotid intima-media thickness (IMT) measurements are used widely to study atherosclerosis. Some have suggested that an increased IMT reflects a nonatherosclerotic adaptive response to changes in shear stress and tensile stress. This stems from the hypothesis that changes in shear stress and subsequently in lumen diameter are followed by changes in IMT to keep tensile stress constant. We studied the relation of common carotid IMT to common carotid end-diastolic lumen diameter and tensile stress, as approximated by mean arterial pressure (lumen diameter/IMT)]. METHODS: A cross-sectional analysis was performed with data obtained from the first 1715 participants in the Rotterdam Study, a population-based cohort study among 7983 subjects aged 55 years and over who underwent ultrasonographic examination of the carotid arteries. End-diastolic lumen diameter and IMT of the common carotid arteries were evaluated and quantified. RESULTS: With increasing IMT, inner and outer lumen diameters increased gradually, and beyond an IMT of 1.10 mm, the inner lumen diameter decreased. Tensile stress increased with increasing lumen diameter instead of being constant. The lumen-to-IMT ratio was constant across levels of mean arterial pressure. CONCLUSIONS: Our findings are compatible with the view that at lower degrees of IMT, the thickening appears to reflect an equilibrium state in which the effects of pressure and flow on the arteries are in balance, given a characteristic relation between shear stress and local transmural pressure. Beyond a certain level, IMT more likely may represent atherosclerosis. Regardless of whether common carotid IMT reflects local atherosclerosis, it may still serve as a graded marker for cardiovascular risk.     

Clinical differentiation of the patient in pain: an introductory guideline for CRNAs

The practical application of colour-coded duplex sonography shows that physico-technical artifacts of colour Doppler imaging may not be obvious in all cases and can lead to misinterpretation. Slice-thickness artifacts are due to restricted transversal resolution, as in the B-mode, and may cause false negative results in vascular occlusions. Specific problems in creating and processing the colour flow image interfere with lateral resolution and lead to errors in the quantification of stenoses from the colour Doppler image. Mirror image artifacts produce phantom pictures that can be easily identified as such in some cases, but may resemble recesses in the arterial wall in other cases. Phenomena of sound shadowing resulting from the same reasons as in B-mode may lead to assume vascular occlusions in cases of long-range stenoses. Artifacts of the sonication angle in case of blood vessel tortuosity may lead to misdiagnosis of a non-existent retrograde flow. The artifacts mentioned do restrict the capacity of colour coded duplex sonography for localising flow in the ultrasound image. Users of the method should therefore be familiar with these artifacts.     

Intrasubject variability of selected force-platform parameters in the quantification of postural control

Platform stabilometry is increasingly applied to monitor or re-educate standing balance in clinical rehabilitation. Consequently, insight is needed into the validity, reliability, and sensitivity of different force-platform parameters. This study focuses on the intrasubject variability as the major source of variance (unreliability) in the study of human motor skills. The intrasubject variability of several, commonly applied force-platform parameters was determined across ten repeated tests of quiet two-legged standing in healthy subjects to identify the most consistent and stable parameters in the quantification of postural control. The variability of the root mean square (RMS) amplitude, peak-to-peak amplitude, mean frequency, and RMS velocity of the fore-aft and lateral components of the center-of-pressure fluctuations was investigated under varying (visual and cognitive) task conditions. The results indicate that all selected parameters show considerable intrasubject variability irrespective of the task context. Nonetheless, both the RMS amplitude and RMS velocity in either direction of sway do not demonstrate a significant trend across repeated tests. Among the selected parameters, the RMS velocity in the fore-aft direction shows the greatest intrasubject consistency, as well as a high sensitivity to, for example, visual deprivation. These findings support the reliability and validity of this parameter in the clinical quantification of postural control.