Improved common carotid elasticity and intima-media thickness measurement from computer analysis of sequential ultrasound frames

Department of Medicine, Division of Cardiology, Atherosclerosis Research Unit, University of Southern California School of Medicine, 2250 Alcazar Street, CSC 132, Los Angeles, CA 90033, USA.
Atherosclerosis (Impact Factor: 3.99). 02/2001; 154(1):185-93. DOI: 10.1016/S0021-9150(00)00461-5
Source: PubMed


B-mode ultrasound has gained popularity as a non-invasive method for direct visualization of superficial vessels. With B-mode ultrasound, arterial stiffness can be directly measured since image acquisition of the arterial wall thickness and vessel diameter can be obtained simultaneously in a dynamic fashion throughout the cardiac cycle. Recently, a method was developed to measure carotid arterial diameter and intima-media thickness (IMT) from B-mode images that utilizes computerized edge tracking-multiframe image processing that automatically measures arterial diameter and IMT in multiple sequential frames spanning several cardiac cycles. To evaluate this method, replicate B-mode common carotid artery ultrasound examinations and blood pressure measurements were obtained in 24 subjects 1-2 weeks apart. Approximately 80 sequential frames spanning two cardiac cycles were analyzed from each ultrasound examination to obtain maximum arterial diameter (D(max)), minimum arterial diameter (D(min)), and IMT using a computerized edge detection method. The intraclass correlations of D(max), D(min), and IMT were 0.97-0.99 and the mean absolute difference for these measurements were 0.03-0.11 mm. The coefficient of variation for D(max) and D(min) were 1.28 and 1.18%, respectively. The intraclass correlation for several standard arterial stiffness indices, Peterson's elastic modulus, Young's modulus, arterial distensibility, compliance, and the beta stiffness index ranged between 0.84 and 0.89. Additionally, it was determined that averaging IMT over five frames centered at D(min) reduced single frame IMT measurement variability by 27% (P=0.005) compared with IMT measured from a single frame corresponding to D(min). Comparison of the phasic relationship of D(max) and D(min) measured from the B-mode ultrasound image with the simultaneously recorded electrocardiogram (ECG) signal in the 24 subjects, provided a more accurate method of frame selection for arterial diameter extrema independent of the ECG signal. The method of computerized edge detection-sequential multiframe image processing presented in this paper represents a technological advance for image analysis of B-mode ultrasound images of common carotid arterial dimensions that is highly reproducible and directly applicable to noninvasive imaging of atherosclerosis.

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Available from: Wendy Mack, Feb 24, 2014
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    • "Several studies hypothesized that arterial stiffness parameters indicate early vascular changes that predict the development of major vascular disease. Indices of arterial stiffness that have been proposed include strain [18], [19], [20], stress [19], [20], elastic modulus or Young's modulus [18], [19], [20], and distensibility coefficient [19], [21], [20]. Van Popele measured carotid wall motion by means of a vessel wall movement detector system [22]. "
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    ABSTRACT: In standard B-mode ultrasound (BMUS), segmentation of the lumen of atherosclerotic carotid arteries and studying the lumen geometry over time are difficult owing to irregular lumen shapes, noise, artifacts, and echolucent plaques. Contrast enhanced ultrasound (CEUS) improves lumen visualization, but lumen segmentation remains challenging owing to varying intensities, CEUS-specific artifacts and lack of tissue visualization. To overcome these challenges, we propose a novel method using simultaneously acquired BMUS&CEUS image sequences. Initially, the method estimates nonrigid motion (NME) from the image sequences, using intensity-based image registration. The motion-compensated image sequence is then averaged to obtain a single 'epitome' image with improved signal-to-noise ratio. The lumen is segmented from the epitome image through an intensity joint-histogram classification and a graph-based segmentation. NME was validated by comparing displacements with manual annotations in eleven carotids. The average root-mean-squareerror (RMSE) was 112 73 μm. Segmentation results were validated against manual delineations in the epitome images of two different datasets, respectively containing eleven (RMSE 191 43 μm) and ten (RMSE 351 176 μm) carotids. From the deformation fields, we derived arterial distensibility with values comparable to the literature. The average errors in all experiments were in the inter-observer variability range. To the best of our knowledge, this is the first study exploiting combined BMUS&CEUS images for atherosclerotic carotid lumen segmentation.
    IEEE Transactions on Medical Imaging 11/2014; 34(4). DOI:10.1109/TMI.2014.2372784 · 3.39 Impact Factor
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    • "Diagram of the experimental setup: the pump pushed the working fluid to circulate and flow through the vessel phantom with elastic walls; pulsatile flow was generated in the vessel; the flow pressure was recorded using the pressure sensor; the B-mode image sequences were acquired using the ultrasonix RP ultrasound system for postprocessing. thickening become perceptible [18], [19], and arterial stiffening plays an important role in the process of CVD. A number of studies examined the ability of arterial stiffness to predict the risk of future fatal and nonfatal cardiovascular events and total mortality [20]–[22]. "
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    ABSTRACT: This study aims to experimentally investigate the impact of vessel stiffness on the flow dynamics of pulsatile vascular flow. Vessel phantoms with elastic walls were fabricated using polyvinyl alcohol cryogel to result in stiffness ranging from 60.9 to 310.3 kPa and tested with pulsatile flows using a flow circulation set-up. Two dimensional instantaneous and time-dependent flow velocity and shear rate vector fields were measured using ultrasonic particle image velocimetry (EchoPIV). The waveforms of peak velocities measured by EchoPIV were compared with the ultrasonic pulse Doppler spectrum, and the measuring accuracy was validated. The cyclic vessel wall motion and flow pressure were obtained as well. The results showed that vessel stiffening influenced the waveforms resulting from vessel wall distension and flow pressure, and the fields of flow velocity and shear rate. The stiffer vessel had smaller inner diameter variation, larger pulse pressure and median pressure. The velocity and shear rate maximized at peak systole for all vessels. The results showed a decrease in wall shear stress for a stiffer vessel, which can initiate the atherosclerotic process. Our study elucidates the impact of vessel stiffness on several flow dynamic parameters, and also demonstrates the EchoPIV technique to be a useful and powerful tool in cardiovascular research.
    IEEE Transactions on Biomedical Engineering 09/2014; 61(9):2444-2450. DOI:10.1109/TBME.2014.2320443 · 2.35 Impact Factor
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    • "The complete ultrasound included: 1) standardized measurements of the far right wall of the distal CCA for IMT, stiffness and lesions and 2) scanning the proximal internal carotid, external carotid and right carotid bulb at the bifurcation for lesions [19]. The ultrasound utilizes computerized and automated edge-tracking multiframe image processing to measure IMT in multiple sequential frames over several cardiac cycles, most frequently 80 frames spanning 2 cardiac cycles [35]. The coefficient of variation was 1.8% (intraclass correlation ¼ 0.98; n ¼ 113) for repeated IMT measurements with the initial images guiding the repeat scans. "
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    ABSTRACT: Background Single nucleotide polymorphisms (SNPs) in the Ryanodine receptor 3 (RYR3) gene are associated with common carotid intima media thickness (CCA cIMT) in HIV-infected men. We evaluated SNPs in the RYR3 gene among HIV-infected women participating in Women's Interagency HIV Study (WIHS). Methods CCA cIMT was measured using B-mode ultrasound and the 838 SNPs in the RYR3 gene region were genotyped using the Illumina HumanOmni2.5-quad beadchip. The CCA cIMT genetic association was assessed using linear regression analyses among 1213 women and also separately among White (n = 139), Black (n = 720) and Hispanic (n = 354) women after adjusting for confounders. A summary measure of pooled association was estimated using a meta-analytic approach by combining the effect estimates from the three races. Haploblocks were inferred using Gabriel's method and haplotype association analyses were conducted among the three races separately. Results SNP rs62012610 was associated with CCA cIMT among the Hispanics (p = 4.41 × 10−5), rs11856930 among Whites (p = 5.62 × 10−4), and rs2572204 among Blacks (p = 2.45 × 10−3). Meta-analysis revealed several associations of SNPs in the same direction and of similar magnitude, particularly among Blacks and Hispanics. Additionally, several haplotypes within three haploblocks containing SNPs previously related with CCA cIMT were also associated in Whites and Hispanics. Discussion Consistent with previous research among HIV-infected men, SNPs within the RYR3 region were associated with subclinical atherosclerosis among HIV-infected women. Allelic heterogeneity observed across the three races suggests that the contribution of the RYR3 gene to CCA cIMT is complex, and warrants future studies to better understand regional SNP function.
    Atherosclerosis 04/2014; 233(2):666–672. DOI:10.1016/j.atherosclerosis.2014.01.035 · 3.99 Impact Factor
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