Carotid plaque morphometric assessment with three-dimensional ultrasound imaging

Abstract

Objective: As investigations into nonsurgical treatment for atherosclerosis expand, the measurement of plaque regression and progression has become an important end point to evaluate. Measurements of three-dimensional (3D) plaque volume are more reliable and sensitive to change than are traditional estimates of stenosis severity or cross-sectional area. 3D ultrasound (3D US) imaging may allow monitoring of plaque volume changes but has not been used routinely due to the cumbersome motorized units required to drive transducers. We investigated the variability, reliability, and the least amount of change detectable by 1D plaque measures, as well as 2D and 3D measures of plaque morphometry, that can be applied in a clinical environment. Methods: 3D US imaging was obtained in 10 patients with carotid stenosis. The lumen and outer wall boundaries were outlined in serial cross-sectional images 1 mm apart. Three observers manually segmented vessel wall volumes (VWVs), and the segmentation was repeated again 4 weeks later. This allowed measurement of interobserver and intraobserver variability of 6 pairs of observations. We measured Bland-Altman statistics, intraclass correlation coefficients, coefficient of variability, and the minimum detectable plaque change for each morphometric measure. Results: The mean VWV of carotid lesions in the study was 1276.8 mm 3 (range, 620.6-1956.3 mm 3). Bland-Altman plots demonstrated low interobserver and intraobserver variability. The interobserver variability of volume measurements as a function of mean volume was 14.8% and interobserver variability was 8.9%. Reliability was 87% as quantified by the interclass correlation and was 95% by the intraclass correlation. The least detectable change in VWV was 12.9% for interobserver variability and 4.5% for intraobserver variability for the three observers. Conclusions: Carotid plaque diameter measurements from B-mode images have high variability. Plaque burden, as estimated by VWV, can be measured reliably with a 3D US technique using a clinical scanner. The volumetric change, with 95% confidence, that must be observed to establish that a plaque has undergone growth or regression is w12.9% for different observers and 4.5% for the same observer performing the follow-up study.

Histopathologic Validation of Grayscale Carotid Plaque Characteristics Related to Plaque Vulnerability

“…All grayscale analyses were performed with 2D ultrasound, utilizing single slice, still images to depict a pulsatile three-dimensional plaque structure, thus leaving room for error in representing the entire plaque throughout the cardiac cycle (Kanber et al 2013b). 3D ultrasound grayscale plaque characterization might offer additional information about the plaque and may be able to provide additional accuracy in evaluating plaque features that are more representative of the histopathology findings (vanEngelen A 2014; AlMuhanna et al 2015). …”

New Insights into Dialysis Vascular Access: Molecular Targets in Arteriovenous Fistula and Arteriovenous Graft Failure and Their Potential to Improve Vascular Access Outcomes

“…High-frequency ultrasound technology has been used in several small studies to evaluate serial intima-medial changes and biomechanics in AVF development (67,68) in the clinical setting and has the potential to serve as a technology to evaluate serial neointimal hyperplasia development and elasticity in a developing AVF. Finally, three-dimensional ultrasonography, which has been used in other fields of vascular disease (69,70) (e.g., carotid atherosclerosis), could also provide a noninvasive method to assess hemodynamic and pathologic changes in AVF development and is potentially translatable to clinical care settings.…”

Non-invasive Carotid Artery Imaging to Identify the Vulnerable Plaque: Current Status and Future Goals

“…29 As 3D US can capture all critical dimensions of the plaque, it has been used in volumetric measurements of the carotid plaque, showing observer variability in the range of 6e15%. 30,31 Although 3D US seems promising, it remains a research tool as solid state 3D probes are in evolution and current techniques are time-consuming. Furthermore, data on the accuracy of 3D ultrasound plaque characterisation with histological validation are limited.…”