High-Frequency Ultrasound for Evaluation of Intimal Thickness

Background: The measurement of carotid intima–medial thickness is a well-validated measure of cardiovascular risk. Although atherosclerosis occurs in the intima, this arterial layer is not measured alone because of the limitation in ultrasound resolution with standard-frequency probes. Methods: We evaluated the feasibility of using a 55-MHz ultrasound system with high resolution to measure intima thickness in several vascular territories compared with a ‘‘standard’’ frequency probe. Results: The intima–medial thickness was measured in the brachial, radial, and tibial arteries in 10 healthy subjects and 5 subjects with peripheral arterial disease. The high-frequency ultrasound probe showed superior resolution compared with the standard-frequency probe, allowing for measurement of intima separately from media. Conclusion: The intima can be measured independently of media with a high degree of reproducibility using a high-frequency probe. This technology may allow for early detection of cardiovascular risk and extend knowledge about the physiologic changes in early atherosclerotic development. (J Am Soc Echocardiogr 2009;22:1129-33.)