A systematic literature review of ultrasonography for morphology and characterization of vulnerable carotid artery plaques

Background and Purpose. - Although ultrasound (US) evaluation of the carotid artery for stenosis is the accepted method for identifying risk factors for cerebrovascular (CV) events, patients with specific plaque morphology may be at increased risk. Plaque characterization via US is a potentially useful adjunct to stenotic grading for identifying vulnerable carotid disease. The aim of this study was to systematically review published clinical trials via the use of US to identify vulnerable plaques among both symptomatic and asymptomatic plaques. Methods. - We used a systematic search using Medline, Embase, and the Cochrane library databases to find relevant studies published between 2001 and 2011. We reviewed randomized, controlled human clinical trials that validated the applicability, diagnostic accuracy, and diagnostic impact of US carotid plaque characterization. For studies reporting qualitative findings, we abstracted information about the study design and technique and the quality of the methodology and analyzed the data using a modified Jadad scale. Results. - In this review, we identified 12 studies related to the evaluation of carotid plaque using US. The studies used a wide range of methodologies to quantify and image the plaque morphology. Published literature on this subject is lacking; however, this deficit may be because current studies are ongoing. Specific plaque characteristics identified as vulnerable included particular echo texture, the presence of echolucency and/or ulceration, surface alterations, and volume assessment using 3-dimensional US (3D US). In a minority of studies investigators used histopathology as the reference standard, and in most they used subsequent clinical observations. All studies demonstrated that US has good accuracy and specificity in identifying possible imaging characteristics related to vulnerable plaques. Conclusion. - The collected evidence shows that US is effectively able to detect specific carotid plaque characteristics related to high-risk plaques vulnerable for CV events. We anticipate that additional well-designed prospective studies will provide more definitive evidence and distinguish specific distinctive findings that may serve as indicators of vulnerable plaques. Our findings must be extended to demonstrate the accuracy and validity in everyday clinical imaging findings.8 page(s

Carotid artery disease imaging : a home-produced, easily made phantom for two- and three-dimensional ultrasound simulation

Background and Purpose: Ultrasound (US) plaque characterization has great potential with regard to maximizing the information traditionally gathered with spectral Doppler examination. It can directly visualize plaque and quantify better features such as surface morphology, geometry, volume, and echotexture via B-mode and the three-dimensional (3D) imaging mechanism. One of the major pitfalls of carotid imaging is the use of freehand manual manipulation. The application of angling, steering, as well as variability in the technical parameters, can increase the interobservation inconsistency. A limited number of commercial phantoms are available to teach this advanced technique but come at a high cost. We developed a home-produced phantom model to practice and teach carotid atherosclerotic disease imaging. We also investigated interobservation variability using two-dimensional (2D) characterization and 3D mechanical planimetry. This study presents a recipe to create an ultrasonic phantom that simulates a diseased carotid artery segment and how it can be used in identifying the 2D and 3D US interobservation variability. Methods: We created five tissue-like phantoms to simulate various types of diseased plaque segments. To simulate the plaque, a piece of frankfurter was cut and detailed to represent various forms of diseased plaque. Each mould contained dissimilar types of mimicked-plaque, including a softplaque, fissured, ulcerated, irregular surfaced, and calcified segment. We used a mixture of gelatin and Metamucil to mimic a previously published soft-tissue mixture. To create a vessel, we used a powder-free, nitrile examination glove. The frankfurter was held in place inside the middle finger of the glove using adhesive gel and filled with mineral oil. Preparation included interval refrigeration of the concoction of the mould. Trained sonographers imaged the plaque using a linear small parts probe for 2D and a mechanical 3D probe for 3D US. Two neuroradiologists assessed the corresponding images and reported their findings including the internal plaque contents, volume, and geometry. Analysis was performed on the inter-observation and inter-reading variability. Results: Interobserver and interreader reliabilities were high, and plaque volume measurement variability decreased with increasing plaque volume. There was increased sensitivity and specificity for each plaque phantom with the use of 3D versus 2D alone. Neuroradiologists reports were 96% sensitive and 97% specific, respectively, when they used combined 2D and 3D US. Conclusion: We created a 2D and 3D vascular US carotid phantom. This phantom is an excellent educational tool to simulate various degrees of diseased carotid segments; moreover, it can be made easily and inexpensively and is reusable. This phantom represents the vessel anatomy and pathology extremely well. We implemented a standardized scanning protocol and created a plaque morphological worksheet to cover all plaque characterization criteria and achieve optimal imaging. Results indicated minimal interobservation and interreader variability. Additional studies are required to address the phantom's longevity and whether or not it can improve the sonographer's skills.5 page(s

Comparison and accuracy of carotid plaque analysis between two- and three-dimensional ultrasound imaging

Plaque characterization using traditional two-dimensional (2D) imaging and/or three-dimensional (3D) ultrasonographic (US) techniques is a new method for evaluating artery wall morphology and plaque risk stratification. The purpose of this study was to assess and compare 2D and 3D US, measuring the interobservation differences for specific plaqueimaging analyses. Phantoms that simulated various types of atherosclerotic plaque pathology were imaged and findings reported by three experienced sonographers. Interobservation agreement and subanalyses were created. For each type of plaque pathology, agreement was moderate; however, conformity increased with the application of 3D US versus 2D US alone. Agreement was best for the identification of fissures, ulcerations, and irregular plaque surface. Advanced sonographic techniques for carotid plaque imaging provide a reproducible method in the analysis and morphologic assessment of simulated carotid atheromatous lesions, with superior interobserver variability. Threedimensional US improves visualization of some pathologies and may provide additional information in the evaluation and risk stratification of vulnerable carotid plaque.8 page(s

Data and code to reproduce: "Initial abundance and stochasticity influence competitive outcome in experimental communities"

This repository contains code and data to reproduce the analyses from:<div><br></div><div>> Dallas,T, G. Legault, B. Melbourne, A.M. Hastings. 2017. "Initial abundance and stochasticity influence competitive outcome in experimental communities"</div><div><br></div

Representative prey population dynamics.

<p>Red and blue lines in each panel give prey dynamics in two patches linked by dispersal, starting from day 20 when dispersal was initiated. (a-d) Failure to achieve synchrony with a dispersal rate of 0.125% per event, (c) slow achievement of synchrony with a dispersal rate of 5% per event, (d) rapid achievement of synchrony with a dispersal rate of 5% per event, (e) failure to achieve synchrony with dispersal rate of 2.5% per event, (f) rapid achievement of synchrony which was subsequently lost with dispersal rate of 2.5% per event, (g-h) rapid achievement of synchrony with a dispersal rate of (g) 9% or (h) 12.5% per event. Compare c-f to <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0079527#pone-0079527-g001" target="_blank">Figure 1</a>.</p

Prey synchrony vs. dispersal rate.

<p>Prey synchrony (<i>z</i>-transformed cross-correlation of log₁₀-transformed prey abundances) as a function of dispersal rate. Each open point gives results from one replicate pair of bottles. The solid curve is <i>y</i> = <i>ax</i>/(<i>b</i>+<i>x</i>) with estimated parameters (95% likelihood profile c.i.) of <i>a</i> = 0.59 (0.39, 1.25), <i>b</i> = 1.27 (0.14,8.50). The curve <i>y</i> = [<i>ax</i>/(<i>b</i>+<i>x</i>)][1+(1-<i>cx</i>)e^−<i>cx</i>] with estimated parameters (95% likelihood profile c.i.) of <i>a</i> = 0.59 (0.45, 1.26), <i>b</i> = 1.22 (0.45, 8.62), <i>c</i> = 14.66 (14.66, 44.64) is hidden by the solid curve. The dotted curve is a piecewise linear regression. The black diamond indicates the estimated location and 95% confidence interval for the discontinuity of the dotted curve. See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0079527#pone.0079527-Hudson1" target="_blank">[34]</a> for review of the concept of profile confidence intervals.</p

Variation in realized synchrony due to demographic stochasticity.

<p>Simulated prey population dynamics in a two-patch Rosenzweig-MacArthur predator-model with demographic stochasticity <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0079527#pone.0079527-Yaari1" target="_blank">[33]</a>. In each panel, red and blue lines show prey dynamics in two patches linked by dispersal of prey and predators at the same per-capita rate. The four panels show four different realizations of the model, using the same parameter values and starting from the same, initially-antisynchronous state. Because the model is stochastic, different realizations can have very different behavior, including (a) slow achievement of synchrony (after ∼50 time units in this example), (b) rapid achievement of synchrony (after ∼12 time units) which is subsequently maintained, (c) failure to achieve synchrony during the simulated time period, and (d) achievement of synchrony (after ∼25 time units) which is subsequently lost. Dynamics were simulated using the SSA algorithm of <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0079527#pone.0079527-Yaari1" target="_blank">[33]</a>, using the following parameter values: attack rate 0.01, handling time 3.0, predator per-capita mortality rate 0.5, predator conversion efficiency 0.4, prey intrinsic rate of increase 2.0 ( =  per-capita birth rate 3.0 - per-capita mortality rate 1.0), prey carrying capacity 1000, prey and predator per-capita dispersal rate 0.05.</p

The CANadian Pediatric Weight management Registry (CANPWR): lessons learned from developing and initiating a national, multi-centre study embedded in pediatric clinical practice

Background: There is increasing recognition of the value of “real-world evidence” in evaluating health care services. Registry-based, observational studies conducted in clinical settings represent a relevant model to achieve this directive. Starting in 2010, we undertook a longitudinal, observational study (the CANadian Pediatric Weight management Registry [CANPWR]), which is embedded in 10 multidisciplinary, pediatric weight management clinics across Canada. The objective of this paper was to share the lessons our team learned from this multi-centre project. Methods: Data sources included a retrospective review of minutes from 120 teleconferences with research staff and investigators, notes taken during clinical site visits made by project leaders, information from quality control processes to ensure data accuracy and completeness, and a study-specific survey that was sent to all sites to solicit feedback from research team members (n = 9). Through an iterative process, the writing group identified key themes that surfaced during review of these information sources and final lessons learned were developed. Results: Several key lessons emerged from our research, including the (1) value of pilot studies and central research coordination, (2) need for effective and regular communication, (3) importance of consensus on determining outcome measures, (4) challenge of embedding research within clinical practice, and (5) difficulty in recruiting and retaining participants. The sites were, in spite of these challenges, enthusiastic about the benefits of participating in multi-centre collaborative studies. Conclusion: Despite some challenges, multi-centre observational studies embedded in pediatric weight management clinics are feasible and can contribute important, practical insights into the effectiveness of health services for managing pediatric obesity in real-world settings.Medicine, Faculty ofNon UBCPediatrics, Department ofReviewedFacult

Additional file 1: of The CANadian Pediatric Weight management Registry (CANPWR): lessons learned from developing and initiating a national, multi-centre study embedded in pediatric clinical practice

Survey utilized to collect data from study sites. (DOC 28 kb