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.