M-line processing for real-time investigation of large artery mechanics

This paper describes the application of an integrated ultrasound (US) system to real-time detection of both blood velocity profile and wall displacements in human arteries. The system simultaneously processes the echo-signals generated from the walls as well as from red blood cells. Wall velocity is detected through the modified autocorrelation algorithm, while the blood velocity profile is obtained through spectral analysis. The system was preliminarily tested in the common carotid arteries of a small group of volunteers. In each case, blood flow behaviour was first checked by detecting the velocity profile inside the vessel. The most appropriate transducer position for vessel wall interrogation was rapidly found by observing in real-time both the velocity profile and the displacements of anterior and posterior walls, which are automatically tracked by the system. The diameter distension was measured in 24 subjects (15 normal volunteers and 9 patients with major risk factors for atherosclerosis). The average distension turned out to be in the range 0.11 - 1.02 mm, with a typical standard deviation within measurement epochs of 26 μm.