Ultrasound Lesions of the Carotid Artery and Risk Factors in Men

The Carotid Atherosclerosis Italian Ultrasound Study (CAIUS) is a multicenter double-blind, placebo-controlled randomized investigation of the effects of Pravastatin on progression of asymptomatic carotid atherosclerosis in outpatients with moderate hypercholesterolemia and without symptoms or signs of coronary heart disease. IntimaMedia Thickness changes of the carotid arteries will be evaluated by B-mode ultrasound imaging. This method allows the detection and monitoring of early lesions and their evolution over time. The study involves approximately 305 patients with moderate hypercholesterolemia, and at least one asymptomatic and uncomplicated early carotid artery lesion. Randomized subjects are in the age range between 45 and 65 yrs. For women a natural or artificial menopause was mandatory. The subjects were randomized to receive either a placebo or an HMG CoA reductase inhibitor (Pravastin 40 mg OD), known to act selectively and primarily on liver cholesterol biosynthesis. The patient follow-up of CAIUS will have a duration of at least 36 months. Every 6 months participating subjects are being monitored by B-mode ultrasound as described in the protocol requiring training and certification of sonographers/readers and centralized reading. The study offers a unique opportunity to monitor the natural history of asymptomatic carotid lesions in hypercholesterolemic patients, as well as to evaluate the effect of a potent cholesterol-lowering medication on progression or regression of carotid atherosclerosis.

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Pravastatin intervention trial on carotid artery atherosclerosis in patients with mild hypercholesterolemia: the CAIUS study

Sirtori¹,

Bianchi²,

Bond³

et al. 1995

“…It has been used in individual patients and in population studies for detection and monitoring of atherosclerosis in clinical trials [20]. Atherosclerosis of the carotid artery has additionally been found to have good correlation with risk factors for development of coronary atherosclerosis [21].…”

Section: Peripheral B-mode Ultrasoundmentioning

confidence: 99%

Perspectives in vascular ultrasound imaging: tissue characterization, 3D reconstruction and vascular mechanics

McPherson

Vonesh

1995

Atherosclerosis is a variable morphologic process resulting in heterogeneous plaque components and nonuniform extent and degree of plaque deposition. We and others have developed techniques of arterial imaging, segmental reconstruction and motion analysis to determine regional vascular reactivity in arterial segments having varying and expanding degrees of atherosclerosis. We have developed and validated position registration devices (PRD) for geometric three dimensional reconstruction of coronary and peripheral arteries using intravascular ultrasound. Elaborating upon an algorithm (McKay et al.), we have developed a technique using biplane cine fluoroscopy to identify intravascular ultrasound image catheter coordinates. Initial data demonstrates clinical feasibility for accurate intracoronary three-dimensional ultrasound reconstruction. For intravascular imaging across occlusions, a prototype 20 MHz forward viewing intravascular ultrasound catheter (Cardiovascular Imaging Systems, Sunnyvale, CA) which provides a two dimensional setting distal to the catheter tip, has been developed. Transcutaneous ultrasound has been used for many years to follow atheroma progression. The use of new position registration devices allows for proper orientation such that accurate three dimensional reconstruction of the carotid bifurcation and the ilio-femoral arteries can be performed. Transesophageal echocardiography is used to evaluate different arterial beds and we have shown in familial hyperlipidemic patients undergoing LDL-apheresis, plaque progression, as determined with transesophageal echocardiography, is delayed. The accurate identification of plaque components would aJlow for better prediction of the effects of lipid modification regimens on plaque progression. We utilized a modified intravascular frequency device for such plaque characterization. Similarly, we are performing Doppler wavefonn frequency, finite element stress and finite analytic flow analysis. Data obtained from the femoral arteries to determine alterations in shear stress with expanding and eccentric atheroma. Taken together, these techniques should allow for quantitative evaluation of structural and functional characteristics of the arterial wall in different vascular beds.

“…The main difficulty for sample size determination in CAIUS study came from the very preliminary knowledge about the mean rate of annual increase of intimamedia thickness within the untreated population, and about its standard deviation [7,8]. Using all information available from previous experiences in this field, we estimated in 0.1 mm/year the mean growth of artery wall, and in 0.05 mm its standard deviation.…”

Section: Sample Sizementioning

confidence: 99%

Statistical issues about serial ultrasonographic measurements in longitudinal studies

Gallus

Veglia²

1995

Monitoring progression of atherosclerotic lesions using B-mode ultrasound imaging is an elaborate task, and requires the application and development of refined statistical techniques. Specific procedures, meant to handle the large amount of data to be processed, to control the variability of the single measurements, and to deal with the incomplete visualisation of artery segments, are necessary in order to benefit of the full power of the studies. Currently, the procedure used to control variability is based on averaging measurements taken at different artery segments, but alternative methods of analysis are also examined in this paper. Different procedures have been proposed by some authors in order to face the problem of missing data, and we are presenting a method based on estimation of non-visualised segments using data from different individuals and based on pattern recognition techniques.