Noninvasive measurement of the pulse wave velocity (PWV) is of high clinical importance. Pulse Wave Imaging (PWI) has been previously developed by our group to visualize the propagation of the pulse wave and to estimate the regional PWV. The objective of this study was to determine the feasibility of PWI in the human carotid artery in vivo. The left common carotid artery of 8 healthy human subjects (27 ± 4 y.o.) was scanned in a long-axis view. The beam density of the 10 MHz linear array was equal to 16 beams so as to increase the frame rate to 1127 Hz for an imaging depth of 25 mm and width of 38 mm. The RF signals were acquired to estimate the velocity of the arterial wall using a 1D cross-correlation technique. Sequential wall velocity frames depicted the propagation of the pulse wave in the carotid artery within the field of view. Regional PWV was estimated from the spatiotemporal variation of the wall velocities and ranged from 4.0 to 5.2 m/s, in agreement with findings in the literature. PWI was thus proven feasible in the human carotid artery.

The mechanical properties of arteries are implicated in a wide variety of cardiovascular diseases, many of which are expected to involve a strong spatial variation in properties that can be depicted by diagnostic imaging. A pulse wave inverse problem (PWIP) is presented, which can produce spatially resolved estimates of vessel compliance from ultrasound measurements of the vessel wall displacements. The 1D equations governing pulse wave propagation in a flexible tube are parameterized by the spatially varying properties, discrete cosine transform components of the inlet pressure boundary conditions, viscous loss constant and a resistance outlet boundary condition. Gradient descent optimization is used to fit displacements from the model to the measured data by updating the model parameters. Inversion of simulated data showed that the PWIP can accurately recover the correct compliance distribution and inlet pressure under realistic conditions, even with severe simulated measurement noise. Silicone phantoms with known compliance contrast were imaged with a clinical ultrasound system .The PWIP produced spatially and quantitatively accurate maps of the phantom compliance compared to independent static property estimates, and the known locations of stiff inclusions (which were as small as 7mm). The PWIP is necessary for these phantom experiments as the spatiotemporal resolution, measurement noise and compliance contrast does not allow accurate tracking of the pulse wave velocity using traditional approaches (e.g. 50% upstroke markers). Results from simulated data suggest reflections generated from material interfaces may negatively affect wave velocity estimates, whereas these reflections are accounted for in the PWIP and do not cause problems.

Patients with periodontitis and no established cardiovascular disease presented with lower degree of uniformity in the transmission of the pulse wave through the carotid arteries, suggesting an association between periodontitis and arterial stiffness/functional alterations.