9.11 VASCULAR PHENOTYPING BY MEANS OF VERY HIGH-RESOLUTION ULTRASOUND IMAGING: A FEASIBILITY ANALYSIS

Abstract

Background: The study of medium and small-size arteries might be useful in the characterization of vascular adaptation, remodeling and wall ultrastructure modifications occurring with aging and in the presence of cardiovascular risk factors. However, to date, these districts have not been extensively explored non-invasively, due to limited spatial resolution power of standard ultrasound (US) machines. Methods: High-frequency US examination by Vevo MD (FUJIFILM, VisualSonics, Toronto, Canada) was performed in 5 healthy volunteers (2 men, mean age: 26.4±3.3 years). Images were obtained at the carotid, brachial and radial artery level, using the 48 MHz (for carotid and brachial) and 70 MHz (for radial) US probes. Mean diameter, relative distension and intima-media thickness (IMT) were obtained using edge detection and contour tracking techniques. Texture analysis was performed on carotid, brachial and radial US images. Contrast, correlation, energy and homogeneity were evaluated from the grey-level co-occurrence matrix calculated on the pixels belonging to the IMT. Results: IMT and relative distension, as well as texture analysis, could be successfully assessed in all the arterial districts evaluated. Correspondent results are reported in Table 1. Conclusions: The multidistrict assessment of wall ultrastructure and mechanics in medium- and small-size arteries is highly feasible in healthy individuals. This kind of analysis might provide novel insight on the development of vascular alterations in previously neglected arterial districts, as well as their clinical significance. Carotid artery Brachial Artery Radial Artery Mean Diameter (mm) 5.9±0.74 3.22±0.65 2.03±0.24 IMT (mm) 0.42±0.05 0.14±0.02 0.12±0.01 Relative distension (%) 10.6±1.8 4±1.7 7.4±2.5 Contrast 0.05±0.008 0.04±0.01 0.05±0.01 Correlation 0.99±0.001 0.99±0.003 0.99±0.001 Energy 0.19±0.05 0.33±0.17 0.23±0.07 Homogeneity 0.97±0.004 0.97±0.005 0.97±0.005