50 results match your criteria far- near-wall


Influence of intrauterine growth status on aortic intima-media thickness and aortic diameter in near-term fetuses: a comparative cross-sectional study.

J Dev Orig Health Dis 2021 Jun 15:1-8. Epub 2021 Jun 15.

Maternal Fetal Medicine Unit, Department of Obstetrics and Gynaecology, Aga Khan University, Pakistan.

Intrauterine undernutrition may lead to fetal vascular programming. We compared abdominal aortic intima-media thickness (aIMT) and aortic diameter (aD) between appropriate for gestational age (AGA) and growth-restricted fetuses (GRF). We recruited 136 singleton fetuses at 34-37 weeks of gestation from Fetal Medicine Unit of Aga Khan University Hospital, Karachi (January-November 2017). Read More

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Impact of Applying a Skin Compression with the Ultrasound Probe on Carotid Artery Strain Elastography.

J Ultrasound Med 2021 May 14. Epub 2021 May 14.

Laboratory of Biorheology and Medical Ultrasonics, University of Montreal Hospital Research Center (CRCHUM), Montréal, Québec, Canada.

Objective: To study the impact of varying the external compression exerted by the ultrasound probe when performing a carotid strain elastography exam.

Methods: Nine healthy volunteers (mean age 43 years ±13 years; 6 men) underwent a vascular ultrasound elastography exam using a custom made sound feedback handle embedding the probe, and allowing the sonographer to adjust the applied compression. A clinical standard practice (SP) force was first recorded, and then predetermined compression (PDC) forces were applied, ranging from 0 to 5 N for the left common carotid artery (CCA) or 2-12 N for the left internal carotid artery (ICA). Read More

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Carotid IMT and Stiffness in the KiGGS 2 National Survey: Third-Generation Measurement, Quality Algorithms and Determinants of Completeness.

Ultrasound Med Biol 2021 02 19;47(2):296-308. Epub 2020 Nov 19.

Robert Koch Institute, Department of Epidemiology and Health Monitoring, Berlin, Germany; German Centre for Cardiovascular Research (DZHK), partner site, Berlin, Germany. Electronic address:

Carotid intima-media thickness (cIMT) and carotid stiffness (CS) are important markers of atherosclerotic risk in the young. We assessed a novel third-generation method for its applicability in large population-based epidemiologic studies to determine strengths, limitations, completeness and predictors of unsuccessful measurement. Four thousand seven hundred ninety-eight 14- to 31-y-old participants of the German KiGGS cohort, which is based on a nationally representative sample with 11-y follow-up, underwent B-mode ultrasound examinations of the left and right common carotid artery with semi-automatic edge detection and automatic electrocardiogram-gated real-time quality control based on a sophisticated snake algorithm and subpixel interpolation. Read More

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February 2021

Microstructure of the near-wall layer of filtration-induced colloidal assembly.

Soft Matter 2020 Nov;16(42):9726-9737

Institut de Mécanique des Fluides de Toulouse, Université de Toulouse, CNRS, Toulouse, France.

This paper describes an experimental study of filtration of a colloidal suspension using microfluidic devices. A suspension of micrometer-scale colloids flows through parallel slit-shaped pores at fixed pressure drop. Clogs and cakes are systematically observed at pore entrance, for variable applied pressure drop and ionic strength. Read More

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November 2020

Vascular deformation in human atherosclerotic carotid artery evaluated by 2D analysis of ultrasonography.

Vascular 2020 Aug 27;28(4):441-449. Epub 2020 Feb 27.

Medical Image and Signal Processing Research Center, Isfahan University of Medical Sciences, Isfahan, Iran.

Objectives: Common carotid artery (CCA) remodelling in the atherosclerosis process is an inherent necessary element that decreases the progress of significant lumen compromise. The present study used a semi-automated method to assess relationships of intima-media thickness (IMT), lumen diameter (LD) and inter-adventitial diameter (IAD) using ultrasound B-mode images of atherosclerotic carotid artery.

Methods: In the cross-sectional study, 120 male subjects (age range: 40-60 years) were classified into four research groups namely control, mild, moderate, and severe stenosis. Read More

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Experimental studies of bubble dynamics inside a corner.

Ultrason Sonochem 2020 Jun 28;64:104951. Epub 2019 Dec 28.

School of Mathematics, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom.

The dynamics of a bubble near a corner formed by two flat rigid boundaries (walls), is studied experimentally using a spark-generated bubble. The expansion, collapse, rebound, re-collapse and migration of the bubble, along with jetting and protrusion, are captured using a high-speed camera. Our experimental observations reveal the behaviour of the bubble in terms of the corner angle and the dimensionless standoff distances to the near and far walls in terms of the maximum bubble radius. Read More

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Characterization and estimation of turbulence-related wall shear stress in patient-specific pulsatile blood flow.

J Biomech 2019 03 19;85:108-117. Epub 2019 Jan 19.

Department of Management and Engineering (IEI), Linköping University, Linköping, Sweden; Center for Medical Image Science and Visualization (CMIV), Linköping University, Linköping, Sweden.

Disturbed, turbulent-like blood flow promotes chaotic wall shear stress (WSS) environments, impairing essential endothelial functions and increasing the susceptibility and progression of vascular diseases. These flow characteristics are today frequently detected at various anatomical, lesion and intervention-related sites, while their role as a pathological determinant is less understood. To present-day, numerous WSS-based descriptors have been proposed to characterize the spatiotemporal nature of the WSS disturbances, however, without differentiation between physiological laminar oscillations and turbulence-related WSS (tWSS) fluctuations. Read More

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Intra- and inter-operator reproducibility of automated cloud-based carotid lumen diameter ultrasound measurement.

Indian Heart J 2018 Sep - Oct;70(5):649-664. Epub 2018 Jan 31.

Monitoring and Diagnostic Division, AtheroPointÔ, Roseville, CA, USA, USA; Point-of-Care Devices, Global Biomedical Technologies, Inc., Roseville, CA, USA; Department of Electrical Engineering, University of Idaho (Affl.), ID, USA. Electronic address:

Background: Common carotid artery lumen diameter (LD) ultrasound measurement systems are either manual or semi-automated and lack reproducibility and variability studies. This pilot study presents an automated and cloud-based LD measurements software system (AtheroCloud) and evaluates its: (i) intra/inter-operator reproducibility and (ii) intra/inter-observer variability.

Methods: 100 patients (83M, mean age: 68±11years), IRB approved, consisted of L/R CCA artery (200 ultrasound images), acquired using a 7. Read More

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January 2019

Bulk Flow and Near Wall Hemodynamics of the Rabbit Aortic Arch: A 4D PC-MRI Derived CFD Study.

J Biomech Eng 2018 Aug 21. Epub 2018 Aug 21.

Division of Cardiology, Department of Medicine, Emory University School of Medicine, Atlanta, GA, 30322.

Animal models offer a flexible experimental environment for studying atherosclerosis. The mouse is the most commonly used animal, however, the underlying hemodynamics in larger animals such as the rabbit are far closer to that of humans. The aortic arch is a vessel with complex helical flow and highly heterogeneous shear stress patterns which may influence where atherosclerotic lesions form. Read More

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Relaminarization by Steady Modification of the Streamwise Velocity Profile in a Pipe.

Flow Turbul Combust 2018 9;100(4):919-943. Epub 2018 Mar 9.

Institute of Science and Technology Austria (IST Austria), Am Campus 1, 3400 Klosterneuburg, Austria.

We show that a rather simple, steady modification of the streamwise velocity profile in a pipe can lead to a complete collapse of turbulence and the flow fully relaminarizes. Two different devices, a stationary obstacle (inset) and a device which injects fluid through an annular gap close to the wall, are used to control the flow. Both devices modify the streamwise velocity profile such that the flow in the center of the pipe is decelerated and the flow in the near wall region is accelerated. Read More

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Towards the prediction of flow-induced shear stress distributions experienced by breast cancer cells in the lymphatics.

Biomech Model Mechanobiol 2017 Dec 24;16(6):2051-2062. Epub 2017 Jul 24.

School of Engineering, Bernal Institute, University of Limerick, Limerick, Ireland.

Tumour metastasis in the lymphatics is a crucial step in the progression of breast cancer. The dynamics by which breast cancer cells (BCCs) travel in the lymphatics remains poorly understood. The goal of this work is to develop a model capable of predicting the shear stresses metastasising BCCs experience using numerical and experimental techniques. Read More

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December 2017

Plaque Tissue Morphology-Based Stroke Risk Stratification Using Carotid Ultrasound: A Polling-Based PCA Learning Paradigm.

J Med Syst 2017 Jun 13;41(6):98. Epub 2017 May 13.

Monitoring and Diagnostic Division, AtheroPoint™, Roseville, CA, USA.

Severe atherosclerosis disease in carotid arteries causes stenosis which in turn leads to stroke. Machine learning systems have been previously developed for plaque wall risk assessment using morphology-based characterization. The fundamental assumption in such systems is the extraction of the grayscale features of the plaque region. Read More

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Stroke Risk Stratification and its Validation using Ultrasonic Echolucent Carotid Wall Plaque Morphology: A Machine Learning Paradigm.

Comput Biol Med 2017 01 27;80:77-96. Epub 2016 Nov 27.

Point-of-Care Devices, Global Biomedical Technologies, Inc., Roseville, CA, USA; Monitoring and Diagnostic Division, AtheroPoint™, Roseville, CA, USA; Department of Electrical Engineering, University of Idaho (Affl.), ID, USA. Electronic address:

Stroke risk stratification based on grayscale morphology of the ultrasound carotid wall has recently been shown to have a promise in classification of high risk versus low risk plaque or symptomatic versus asymptomatic plaques. In previous studies, this stratification has been mainly based on analysis of the far wall of the carotid artery. Due to the multifocal nature of atherosclerotic disease, the plaque growth is not restricted to the far wall alone. Read More

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January 2017

Associations of Coronary Heart Disease with Common Carotid Artery Near and Far Wall Intima-Media Thickness: The Multi-Ethnic Study of Atherosclerosis.

J Am Soc Echocardiogr 2015 Sep 2;28(9):1114-21. Epub 2015 May 2.

Department of Radiology, Saint Elizabeth's Medical Center, Tufts University School of Medicine, Boston, Massachusetts.

Background: Intima-media thickness (IMT) measured on ultrasound images of the common carotid artery (CCA) is associated with cardiovascular risk factors and events. Given the physics of ultrasound, CCA far wall IMT measurements are favored over near wall measurements, but this theoretical advantage is not well studied.

Methods: A total of 6,606 members of the Multi-Ethnic Study of Atherosclerosis, a longitudinal cohort study (mean age, 62. Read More

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September 2015

Efficacy and spatial distribution of ultrasound-mediated clot lysis in the absence of thrombolytics.

Thromb Haemost 2015 Jun 26;113(6):1357-69. Epub 2015 Mar 26.

Azzdine Y. Ammi, PhD, Knight Cardiovascular Institute, UHN-62, Oregon Health & Science University, 3181 SW Sam Jackson Park Rd., Portland, OR 97239, USA, Tel.: +1 503 494 8750, Fax: +1 503 494 8550, E-mail:

Ultrasound and microbubble (MB) contrast agents accelerate clot lysis, yet clinical trials have been performed without defining optimal acoustic conditions. Our aim was to assess the effect of acoustic pressure and frequency on the extent and spatial location of clot lysis. Clots from porcine blood were created with a 2-mm central lumen for infusion of lipid-shelled perfluorocarbon MBs (1×10(7) ml(-1)) or saline. Read More

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Lateral migration of a spherical capsule near a plane wall in Stokes flow.

Phys Rev E Stat Nonlin Soft Matter Phys 2014 Oct 15;90(4):043009. Epub 2014 Oct 15.

Department of Bioengineering and Robotics, Tohoku University 6-6-01 Aramaki-aza Aoba, Aoba-ku, Sendai 980-8579, Japan.

Lateral migration is the motion of a particle perpendicular to the direction of the surrounding flow. One of the factors leading to the lateral migration of a deformable particle in Stokes flow is the presence of a nearby wall. We numerically investigate the lateral migration of a capsule in a near-wall simple shear flow using a boundary integral method coupled with a finite element method. Read More

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October 2014

Computational modelling of emboli travel trajectories in cerebral arteries: influence of microembolic particle size and density.

Biomech Model Mechanobiol 2014 Apr 2;13(2):289-302. Epub 2014 Mar 2.

Brunel Institute for Bioengineering, Brunel University, Uxbridge, Middlesex , UB8 3PH, UK.

Ischaemic stroke is responsible for up to 80% of stroke cases. Prevention of the reoccurrence of ischaemic attack or stroke for patients who survived the first symptoms is the major treatment target. Accurate diagnosis of the emboli source for a specific infarction lesion is very important for a better treatment for the patient. Read More

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Transcutaneous very-high resolution ultrasound for the quantification of carotid arterial intima-media thickness in children - feasibility and comparison with conventional high resolution vascular ultrasound imaging.

Atherosclerosis 2012 Sep 27;224(1):102-7. Epub 2012 Jun 27.

Labatt Family Heart Centre, The Hospital for Sick Children, University of Toronto, 555 University Avenue, Toronto, ON M5G 1X8, Canada.

Objective: To study the accuracy and feasibility of very-high resolution ultrasound (VHRU, 25-55 MHz) and conventional high resolution ultrasound (HRU, 12 MHz) in the assessment of common carotid intima-media thickness (IMT) in healthy children between 0 and 18 years of life.

Methods: IMT was measured with VHRU and HRU in 135 children. Seventeen similar sized porcine arterial specimens were imaged with VHRU and HRU, and the IMT measurements compared to histology. Read More

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September 2012

Automatic segmentation of carotid B-mode images using fuzzy classification.

Med Biol Eng Comput 2012 May 14;50(5):533-45. Epub 2012 Mar 14.

INEB-Instituto de Engenharia Biomédica, Rua Dr. Roberto Frias, s/n, 4200-465 Porto, Portugal.

This paper presents a new method for the automatic segmentation of the common carotid artery in B-mode images. This method uses the instantaneous coefficient of variation edge detector, fuzzy classification of edges and dynamic programming. Several discriminating features of the intima and adventitia boundaries are considered, like the edge strength, the intensity gradient orientation, the valley shaped intensity profile and contextual information of the region delimited by those boundaries. Read More

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Dose-dependent artifact in the far wall of the carotid artery at dynamic contrast-enhanced US.

Radiology 2012 Feb 9;262(2):672-9. Epub 2011 Dec 9.

Academic Section of Vascular Surgery and Department of Experimental Medicine, Imperial College London, Hammersmith Hospital, Du Cane Road, London W12 0HS, England.

Purpose: To quantify a pseudoenhancement phenomenon observed during dynamic contrast material-enhanced ultrasonography (US) of the carotid artery, both in vitro and in vivo.

Materials And Methods: Ethical approval was obtained prior to commencing this prospective case series, and each patient gave written informed consent. Thirty-one patients with 50%-99% internal carotid artery stenosis underwent dynamic contrast-enhanced US of the carotid bifurcation with use of 2 mL of microbubbles. Read More

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February 2012

Extensive or restricted ultrasound protocols to measure carotid intima-media thickness: analysis of completeness rates and impact on observed rates of change over time.

J Am Soc Echocardiogr 2012 Jan 7;25(1):91-100. Epub 2011 Oct 7.

Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands.

Background: Ultrasound protocols to measure carotid intima-media thickness (CIMT) vary considerably with regard to carotid sites and angles that are assessed. Measurements from the carotid bifurcation and internal carotid artery are thought to be affected by large numbers of missing data. Actual published quantification of completeness rates and the relation with cardiovascular risk factors, however, is scarce. Read More

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January 2012

Scattering effects at near-wall flow measurements using Doppler global velocimetry.

Appl Opt 2011 Jul;50(21):4068-82

Laboratory for Measurement and Testing Techniques, Technische Universität Dresden, Helmholtzstr. 18, 01062 Dresden, Germany.

Doppler global velocimetry (DGV) is considered to be a useful optical measurement tool for acquiring flow velocity fields. Often near-wall measurements are required, which is still challenging due to errors resulting from background scattering and multiple-particle scattering. Since the magnitudes of both errors are unknown so far, they are investigated by scattering simulations and experiments. Read More

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Relationship between tooth loss and carotid intima-media thickness in Korean adults.

J Adv Prosthodont 2010 Dec 31;2(4):122-7. Epub 2010 Dec 31.

Department of Prosthodontics, Graduate School of Clinical Dentistry, Korea University, Seoul, Korea.

Purpose: The aim of this study was to examine the relationship between tooth loss and sub-clinical atherosclerosis in Korean adults.

Materials And Methods: The subjects were part of a cohort study conducted in Ansan city by the Korea University medical school as part of the Korean Genome project. 749 subjects over than 40 years old were evaluated. Read More

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December 2010

Apolipoprotein B, non-HDL cholesterol and LDL cholesterol for identifying individuals at increased cardiovascular risk.

J Intern Med 2010 Dec;268(6):567-77

Division of Vascular Medicine, Department of General Internal Medicine, Radboud University, Nijmegen Medical Centre, Nijmegen, The Netherlands.

Background: To compare apolipoprotein B (apoB), non-high-density lipoprotein-cholesterol (non-HDL-c) and low-density lipoprotein-cholesterol (LDL-c) for identifying individuals with a deteriorated cardiovascular (CV) risk profile, including a panel of subclinical atherosclerosis measurements and prevalent cardiovascular disease (CVD) in a Dutch population-based cohort.

Methods: Clinical and biochemical measurements and a panel of noninvasive parameters of subclinical atherosclerosis were determined in 1517 individuals, aged 50-70 years.

Results: Both men and women with increasing levels of apoB and non-HDL-c were more obese, had higher blood pressure and fasting glucose levels, and a more atherogenic lipid profile. Read More

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December 2010

Modeling performance of a two-dimensional capsule in a microchannel flow: long-term lateral migration.

Authors:
Hua Li Gang Ma

Phys Rev E Stat Nonlin Soft Matter Phys 2010 Aug 10;82(2 Pt 2):026304. Epub 2010 Aug 10.

Nanyang Technological University, Singapore 639798, Singapore.

The long-term lateral migration of a two-dimensional elastic capsule in a microchannel is studied numerically in this paper. The numerical method combines a finite volume technique for solving the fluid problem with a front tracking technique for capturing and tracking the capsule membrane. The capsule is modeled as a liquid medium enclosed by a thin membrane which has linear elastic properties. Read More

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Evaluation of an algorithm for arterial lumen diameter measurements by means of ultrasound.

Med Biol Eng Comput 2010 Nov 16;48(11):1133-40. Epub 2010 Jul 16.

Electrical Measurements, Faculty of Engineering, LTH, Lund University, Box 118, 221 00, Lund, Sweden.

We have developed an algorithm for arterial luminal diameter measurement by means of ultrasound and evaluated the algorithm on agar vessel phantoms and in vivo. The algorithm utilises relative threshold detection on the inner slopes of the arterial walls before the resolution is improved by solving the equation of a straight line between the samples around the threshold value. Further, correction distances added to compensate for the underestimation when using the inner slopes were found to be 304 μm for the near wall and 415 μm for the far wall. Read More

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November 2010

Completeness of carotid intima media thickness measurements depends on body composition: the RADIANCE 1 and 2 trials.

J Atheroscler Thromb 2010 May 13;17(5):526-35. Epub 2010 Mar 13.

Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, the Netherlands.

Aim: Ultrasound protocols to measure carotid intima media thickness (CIMT) differ considerably with regard to the inclusion of the number of carotid segments and angles used. Detailed information on the completeness of CIMT information is often lacking in published reports, and at most, overall percentages are presented. We therefore decided to study the completeness of CIMT measurements and its relation with vascular risk factors using data from two CIMT intervention studies: one among familial hypercholesterolemia (FH) patients, the Rating Atherosclerotic Disease change by Imaging With A New CETP Inhibitor (RADIANCE 1), and one among mixed dyslipidemia (MD) patients, the Rating Atherosclerotic Disease change by Imaging With A New CETP Inhibitor (RADIANCE 2). Read More

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The intensity correlation function in evanescent wave scattering.

J Chem Phys 2010 Feb;132(7):074704

Institute of Theoretical Physics, University of Warsaw, Hoza 69, 00-681 Warsaw, Poland.

As a first step toward the interpretation of dynamic light scattering with evanescent illumination from suspensions of interacting spheres, in order to probe their near wall dynamics, we develop a theory for the initial slope of the intensity autocorrelation function. An expression for the first cumulant is derived that is valid for arbitrary concentrations, which generalizes a well-known expression for the short-time, wave-vector dependent collective diffusion coefficient in bulk to the case where a wall is present. Explicit expressions and numerical results for the various contributions to the initial slope are obtained within a leading order virial expansion. Read More

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February 2010

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

Ultrasound Med Biol 2010 Feb 16;36(2):218-26. Epub 2009 Dec 16.

Wallenberg Laboratory for Cardiovascular Research, and Center for Cardiovascular and Metabolic Research, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.

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. Read More

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February 2010

Carotid atherosclerosis and the risk factors in early postmenopausal Chinese women.

Maturitas 2009 Jul 13;63(3):233-9. Epub 2009 May 13.

Department of Community and Family Medicine, The Chinese University of Hong Kong, Hong Kong.

Objectives: To describe the distribution of intima-media thickness (IMT) and the prevalence of plaque by carotid segments, walls and sides, and to examine their associated risk factors in asymptomatic, early postmenopausal Chinese women in Hong Kong.

Methods: Between 2002 and 2004, the study recruited 518 postmenopausal women aged 50-64 years. They were examined by B-mode ultrasound to measure the IMT and the prevalence of plaque at the near and far walls of common carotid (CCA), bifurcation (bulb), and internal carotid (ICA) of both the left and right carotid arteries. Read More

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