The value of non-invasive vascular elastography (NIVE) in detecting early vascular changes in overweight and obese children

Effects of polyphenol supplementation on hepatic steatosis, intima-media thickness and non-invasive vascular elastography in obese adolescents: a pilot study protocol

INTRODUCTION

Non-alcoholic fatty liver disease (NAFLD) is increasingly prevalent in obese adolescents. Increased systemic inflammation and decreased gut microbial diversity linked to obesity affect the liver and are also associated with cardiovascular diseases in adulthood. However, NAFLD and vascular alterations are reversible.

METHODS AND ANALYSIS

This pilot study evaluated the feasibility of a prospective open-label randomised controlled trial evaluating the effects of polyphenols on NAFLD and vascular parameters in obese adolescents. Children aged 12-18 years with hepatic steatosis (n=60) will be recruited. The participants will be randomised with a 1:1 allocation ratio to receive polyphenol supplementation one time per day for 8 weeks along with the clinician-prescribed treatment (group B, n=30) or to continue the prescribed treatment without taking any polyphenols (group A, n=30). The outcome measures will be collected from both the groups at day 1 before starting polyphenol supplementation, at day 60 after 8 weeks of supplementation and at day 120, that is, 60 days after supplementation. The changes in hepatic steatosis and vascular parameters will be measured using liver and vascular imaging. Furthermore, anthropometric measures, blood tests and stool samples for gut microbiome analysis will be collected. After evaluating the study's feasibility, we hypothesise that, as a secondary outcome, compared with group A, the adolescents in group B will have improved NAFLD, vascular parameters, systemic inflammation and gut microbiome.

ETHICS AND DISSEMINATION

This study is approved by Health Canada and the hospital ethics. Participants and their parents/tutors will both provide consent. Trial results will be communicated to the collaborating gastroenterologists who follow the enrolled participants. Abstracts and scientific articles will be submitted to high-impact radiological societies and journals.

CLINICALTRIALS

gov ID: NCT03994029. Health Canada authorisation referral number: 250 811. Protocole version 13, 2 June 2023.

TRIAL REGISTRATION NUMBER

NCT03994029.

Normal pediatric values of carotid artery intima-media thickness measured by B-mode ultrasound and radiofrequency echo tracking respecting the consensus: a systematic review

BACKGROUND

Carotid artery intima-media thickness (IMT) is a sub-clinical radiologic marker of atherosclerosis in children. It is associated with adult-onset vascular disease.

OBJECTIVE

To determine normal pediatric values of IMT from results observed in the literature.

METHODS

Our systematic review was conducted according to PRISMA guidelines. We reviewed 2298 English articles from inception to February 2023. Inclusion criteria included studies evaluating B-mode and radiofrequency (RF)-based IMT measurements based on the American Heart Association, the Association for European Pediatric Cardiology, the Mannheim Consensus, and the American Society of Echocardiography recommendations. A meta-analysis of aggregate data was conducted to obtain the confidence interval (CI) for IMT, using a 95% confidence level.

RESULTS

We obtained 88 B-mode-based IMT measurement studies with 6184 children and six radiofrequency echo-tracking-based studies with 766 children. Mean IMT in the pediatric population was 0.43 mm, 95% [CI] 0,42 to 0.44, using the B-mode technique, and 0.41 mm, 95% [CI] 0.36 to 0.45 using the radiofrequency technique. No significant relationship was detected between IMT and age (p value = 0.83). Finally, no significant effect of sex on IMT was found (p value = 0.82 for B-mode and p value = 0.62 for RF).

CONCLUSION

Based on the studies selected in this literature review, we were unable to conclude that there was a significant difference between the average IMT of boys and girls. No relationship was demonstrated between age and IMT. IMT is technique-specific, and normal values should be interpreted according to recommendations of recognized consensus to counteract the current heterogeneity in literature.

CLINICAL RELEVANCE STATEMENT

Technique and children-specific Intima media thickness measurements help clinicians and scientists to assess the risk of atherosclerosis in children.

KEY POINTS

• Intima-media thickness (IMT) does not correlate with age in children without risk factors. • According to current literature, there is no difference in IMT between healthy boys and girls. • There is heterogeneity, even with studies abiding by the official consensus.

Non-Invasive Vascular Elastography as a One-Step Imaging Technique to Evaluate Early Vascular Changes in Children Compared to B-Mode-Based Intima-Media Thickness Technique : A Validation Study Using Inter- and Intra-Rater Reliability

Background: Childhood obesity is linked to higher adult mortality and morbidity from atherosclerosis. It is primordial to detect at-risk children earlier-on to prevent disease progression. Carotid intima-media thickness (IMT) is a subclinical radiological marker for early atherosclerosis. B-mode ultrasound is a known technique to assess IMT, but no gold standard technique exists in children. Non-invasive vascular elastography (NIVE) using speckle statistics is an innovative alternative to evaluate IMT and adds by providing translation, strain and shear strain measurements. Validation studies for both techniques lack in children. Purpose: Validate the reproducibility of the 2 techniques in Canadian children. Methods: We conducted a prospective study where anthropometry, blood pressure, IMT and elastography were measured. Six operators obtained 2 measurements for both carotid arteries using both techniques, for a total of 720 measurements. Inter- and intra-class correlation coefficients (ICC) were calculated for each measurement technique and elastography parameters. Results: 30 participants (13.0 ± 1.26 years, 17 girls) were recruited. Twelve were overweight. No significant difference was found in mean IMT between weight groups for either technique (P = .15 and P = .60). We found excellent inter- (ICC = .98 [95% Confidence Interval (CI): .97; .99]) and intra- (ICC = .90-.93) operator reliability for the B-mode technique, and good inter (ICC = .70 [95% CI: .47; .85]) and intra- (ICC = .71-.91) operator reliability for the NIVE-based technique. Poor reliability was found between techniques (ICC = .30 [95% CI: -.31; .65). For elastography parameters, translation was the most reliable (ICC = .94-.95). Conclusion: IMT measurement is reproducible in children but not between techniques. NIVE gives the advantage of evaluating elastography.

Associative Prediction of Carotid Artery Plaques Based on Ultrasound Strain Imaging and Cardiovascular Risk Factors in People Living With HIV and Age-Matched Control Subjects of the CHACS Cohort

BACKGROUND

There is a need for a specific atherosclerotic risk assessment for people living with HIV (PLWH).

SETTING

A machine learning classification model was applied to PLWH and control subjects with low-to-intermediate cardiovascular risks to identify associative predictors of diagnosed carotid artery plaques. Associations with plaques were made using strain elastography in normal sections of the common carotid artery and traditional cardiovascular risk factors.

METHODS

One hundred two PLWH and 84 control subjects were recruited from the prospective Canadian HIV and Aging Cohort Study (57 ± 8 years; 159 men). Plaque presence was based on clinical ultrasound scans of left and right common carotid arteries and internal carotid arteries. A classification task for identifying subjects with plaque was defined using random forest (RF) and logistic regression models. Areas under the receiver operating characteristic curves (AUC-ROCs) were applied to select 5 among 50 combinations of 4 or less features yielding the highest AUC-ROCs.

RESULTS

To retrospectively classify individuals with and without plaques, the 5 most discriminant combinations of features had AUC-ROCs between 0.76 and 0.79. AUC-ROCs from RF were statistically significantly higher than those obtained with logistic regressions ( P = 0.0001). The most discriminant features of RF classifications in PLWH were age, smoking status, maximum axial strain and pulse pressure (equal weights), and sex and antiretroviral therapy exposure (equal weights). When considering the whole population, the HIV status was identified as a cofactor associated with carotid artery plaques.

CONCLUSIONS

Strain elastography adds to traditional cardiovascular risk factors for identifying individuals with carotid artery plaques.

Current applications for measuring pediatric intima-media thickness

Intima-media thickness is a known subclinical radiologic marker of the early manifestations of atherosclerotic disease. It is the thickness of the vessel wall, most often the carotid artery. Intima-media thickness is measured on conventional US manually or automatically. Other measurement techniques include radiofrequency US. Because there is variation in its measurement, especially in children, several recommendations have been set to increase the measurement's validity and comparability among studies. Despite these recommendations, several pitfalls should be avoided, and quality control should be performed to avoid erroneous interpretation. This article summarizes current literature in relation to the clinical applications for intima-media thickness measurement in children with known risk factors such as obesity, liver steatosis, hypercholesterolemia, diabetes, hypertension, systemic inflammatory diseases, cancer survival, kidney and liver transplant, and sickle cell disease or beta thalassemia major. Most potential indications for intima-media thickness measurement remain in the research domain and should be interpreted combined with other markers. The objective of diagnosing an increased intima-media thickness is to start a multidisciplinary treatment approach to prevent disease progression and its sequelae in adulthood.

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

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). Six carotid elastography features, namely maximum and cumulated axial strains, maximum and cumulated shear strains, cumulated axial translation, and cumulated lateral translation were assessed with noninvasive vascular elastography (NIVE) on near and far walls of carotids. The carotid intima media thickness (IMT) and diameter were also measured.

RESULTS

All elastography features on the near wall of both CCA and ICA decreased statistically significantly as the PDC force increased; this association was also observed for half of the features on the far wall. Three NIVE features at the lowest PDC force (out of 72 that were tested) were statistically significantly different than values at the SP force. Overall, NIVE showed some variance to probe compression with linear regression slopes revealing changes of 10.1%-45.6% in magnitude over the whole compression range on both walls. The maximum IMT for the ICA near wall, and carotid lumen diameters of both CCA and ICA were statistically significantly associated with PDC forces; these features underwent a decrease of 10.2%, 36.2%, and 17.6%, respectively, over the whole range of PDC force increase. Other IMT measurements were not statistically significantly associated with applied PDC forces.

CONCLUSION

These results suggest the need of technical guidelines for carotid strain elastography. Using the lowest probe compression while allowing a good B-mode image quality is recommended to improve the robustness of NIVE measurements.

Evaluation of carotid artery stiffness in patients with coronary artery disease using acoustic radiation force impulse elastography

OBJECTIVES

We evaluated carotid artery stiffness in patients with coronary artery disease (CAD) using acoustic radiation force impulse (ARFI) elastography and investigated the relationship between stiffness and CAD.

METHODS

This study examined 76 CAD patients (aged 60.7 ± 11) and 70 healthy individuals (aged 59.6 ± 9). The left common carotid artery mean shear wave velocity (LCmeanSWV) and the right common carotid artery mean shear wave velocity (RCmeanSWV) of the anterior walls were measured using ARFI elastography, and the results of the patient group and the healthy group were compared. The common carotid intima-media thickness (CIMT) was measured in both groups and compared with mean SWV.

RESULTS

The RCmeanSWVs in the patient and healthy groups were 3.47 ± 1 m/s and 2.69 ± 0.90 m/s, respectively (p < 0.001). The LCmeanSWVs in the patient and healthy groups were 3.60 ± 0.9 m/s and 2.90 ± 0.80 m/s, respectively (p < 0.001). A significant correlation was found between the RCmeanSWV and the right CIMT values and between the LCmeanSWV and the left CIMT values (r = 0.231, p = 0.03 and r = 0.331, p = 0.002, respectively).

CONCLUSIONS

The mean SWV values of carotid arteries of CAD patients measured with ARFI elastography were significantly higher than the mean SWV values of the carotid arteries of healthy individuals. Thus, measurement of the carotid artery SWV could be a potential tool in the risk evaluation of cardiovascular disease. Nonetheless, new studies are required to determine whether this method serves as a useful additional tool.

Pulse Wave Imaging Coupled With Vector Flow Mapping: A Phantom, Simulation, and In Vivo Study

Pulse wave imaging (PWI) is an ultrasound imaging modality that estimates the wall stiffness of an imaged arterial segment by tracking the pulse wave propagation. The aim of the present study is to integrate PWI with vector flow imaging, enabling simultaneous and co-localized mapping of vessel wall mechanical properties and 2-D flow patterns. Two vector flow imaging techniques were implemented using the PWI acquisition sequence: 1) multiangle vector Doppler and 2) a cross-correlation-based vector flow imaging (CC VFI) method. The two vector flow imaging techniques were evaluated in vitro using a vessel phantom with an embedded plaque, along with spatially registered fluid structure interaction (FSI) simulations with the same geometry and inlet flow as the phantom setup. The flow magnitude and vector direction obtained through simulations and phantom experiments were compared in a prestenotic and stenotic segment of the phantom and at five different time frames. In most comparisons, CC VFI provided significantly lower bias or precision than the vector Doppler method ( ) indicating better performance. In addition, the proposed technique was applied to the carotid arteries of nonatherosclerotic subjects of different ages to investigate the relationship between PWI-derived compliance of the arterial wall and flow velocity in vivo. Spearman's rank-order test revealed positive correlation between compliance and peak flow velocity magnitude ( rs = 0.90 and ), while significantly lower compliance ( ) and lower peak flow velocity magnitude ( ) were determined in older (54-73 y.o.) compared with young (24-32 y.o.) subjects. Finally, initial feasibility was shown in an atherosclerotic common carotid artery in vivo. The proposed imaging modality successfully provided information on blood flow patterns and arterial wall stiffness and is expected to provide additional insight in studying carotid artery biomechanics, as well as aid in carotid artery disease diagnosis and monitoring.

Absent atherosclerotic risk factors are associated with carotid stiffening quantified with ultrafast ultrasound imaging

OBJECTIVES

To evaluate carotid stiffening in participants without conventional cardiovascular risk factors (CVRFs) by using ultrafast pulse wave velocity (ufPWV).

METHODS

The present study enrolled 517 participants without conventional CVRFs (CVRF-Free total population). Subjects in this population were defined as current non-smokers with untreated blood pressure < 140/90 mmHg, fasting blood glucose (FBG) < 7.0 mmol/L, total cholesterol (TC) < 6.2 mmol/L, low-density lipoprotein cholesterol < 4.1 mmol/L, and high-density lipoprotein cholesterol ≥ 1.0 mmol/L. Participants in the subgroup with optimal CVRFs (CVRF-Optimal subgroup; n = 188) were defined as having blood pressure < 120/80 mmHg, TC < 5.2 mmol/L, and FBG < 5.6 mmol/L. Clinical interviews, physical examinations, serum draw, carotid intima-media thickness (cIMT), and ufPWV were evaluated. Adjusted odds ratios (ORs) with 95% confidence intervals and ordinal logistic regression models were used.

RESULTS

Carotid stiffening was present in 46.2-54.5% of CVRF-Free subjects. Age, male sex, and body mass index (BMI) were independently associated with carotid stiffening in both the CVRF-Free total population and CVRF-Optimal subgroup (OR for age = 1.10-1.11, OR for male sex = 2.65-7.19, OR for BMI = 1.34-1.62; p < 0.05). Carotid stiffening was associated with TC only in the CVRF-Free total population (OR for TC = 1.84; p = 0.034).

CONCLUSIONS

Many CVRF-Free individuals have carotid stiffening. ufPWV for atherosclerotic stiffening aids the assessment of early atherogenesis and may further clarify the true status of healthy adults without CVRFs.

KEY POINTS

• CVRF-Optimal individuals have a lower carotid stiffness than CVRF-Free populations. • ufPWV is a quantitative predictor for the early assessment of AS. • Absent major CVRFs cannot be considered low risk for carotid stiffening and atherosclerosis.

Adaptive Pulse Wave Imaging: Automated Spatial Vessel Wall Inhomogeneity Detection in Phantoms and in-Vivo

Imaging arterial mechanical properties may improve vascular disease diagnosis. Pulse wave velocity (PWV) is a marker of arterial stiffness linked to cardio-vascular mortality. Pulse wave imaging (PWI) is a technique for imaging the pulse wave propagation at high spatial and temporal resolution. In this paper, we introduce adaptive PWI, a technique for the automated partition of heterogeneous arteries into individual segments characterized by most homogeneous pulse wave propagation, allowing for more robust PWV estimation. This technique was validated in a silicone phantom with a soft-stiff interface. The mean detection error of the interface was 4.67 ± 0.73 mm and 3.64 ± 0.14 mm in the stiff-to-soft and soft-to-stiff pulse wave transmission direction, respectively. This technique was tested in monitoring the progression of atherosclerosis in mouse aortas in vivo ( n = 11 ). The PWV was found to already increase at the early stage of 10 weeks of high-fat diet (3.17 ± 0.67 m/sec compared to baseline 2.55 ± 0.47 m/sec, ) and further increase after 20 weeks of high-fat diet (3.76±1.20 m/sec). The number of detected segments of the imaged aortas monotonically increased with the duration of high-fat diet indicating an increase in arterial wall property inhomogeneity. The performance of adaptive PWI was also tested in aneurysmal mouse aortas in vivo. Aneurysmal boundaries were detected with a mean error of 0.68±0.44 mm. Finally, initial feasibility was shown in the carotid arteries of healthy and atherosclerotic human subjects in vivo ( n = 3 each). Consequently, adaptive PWI was successful in detecting stiffness inhomogeneity at its early onset and monitoring atherosclerosis progression in vivo.