Introduction: The radiofrequency (RF) matrix conveys information on texture and composition of atherosclerotic plaques. Few studies have analyzed the “normal” carotid wall out of plaques. We tested a novel method to measure echoes from the media layer and analyzed their correlation with clinical variables and arterial stiffness in a large population sample.

Methods: We analyzed RF matrices from ultrasound scans of the common carotid in 1,827 untreated subjects recruited from the general population, aged 50 to 75, for the Etude Prospective Parisienne 3. The first strong echo from the blood-intima interface was excluded; media power (MP) was defined as the ratio of amplitude of RF echoes from the media and that from the lumen. Intima-media thickness (IMT) was also measured.

Results: IMT was correlated with carotid diameter, age, pressure, and body size. MP was inversely correlated with body size and serum lipids, but not with age or pressure. IMT was higher, and MP lower, in obesity and metabolic syndrome (MS); obese with MS had higher IMT, and lower MP, than non-obese non-MS; the difference in MP was significant also for these latter vs. non-obese with MS. MP was positively correlated with distensibility (r=0.097, p<0.001) and inversely with Young’s modulus (r=−0.121, p<0.001); IMT had a negative correlation with both.

Conclusion: Obesity and MS decrease echogenicity of the carotid media. MP is influenced by different parameters than IMT, and conveys different information; it is inversely correlated with intrinsic and total vessel stiffness. Its histological and clinical meaning are to be investigated.