Validation of a newly developed B-mode image-processing technique versus wall-tracking ultrasound for the study of wall mechanics in small-calibre arteries

Purpose: To validate a newly developed image‐processing technique for the assessment of arterial wall compliance and distensibility from non‐invasive B‐mode ultrasound compared with the invasive wall‐tracking technique. Materials and methods: Arterial wall compliance and distensibility coefficient were measured invasively by wall‐tracking with an ultrasonic transducer implanted on the vessel wall, and non‐invasively by automatic processing of B‐mode ultrasound images, with a dedicated workstation and software (IO^ 3·1, IO^DP, Paris). Measurements were performed in the normal aorta of five animals, and upstream, at the stent level, and downstream from the stent in eight other animals (immediately after stenting in six, and 3 months later in four), for a total of 35 paired measurements. Results: There was no significant difference between the two techniques for compliance but there was a significant difference in diameter (P<0·005) and distensibility (P<0·05) as external ultrasound measured the inner diameter, while wall‐tracking measured the outer diameter. Agreement between the two methods as assessed by the Bland–Altman approach was acceptable for aortic diameter, compliance and distensibility. Conclusion: Automatic processing of B‐mode ultrasound images is a reliable non‐invasive technique to assess the compliance of small‐calibre arteries.