Feasibility and Validation of 4-D Pulse Wave Imaging in Phantoms and In Vivo

Abstract

Pulse wave Imaging (PWI) is a noninvasive technique for tracking the propagation of the pulse wave along the arterial wall. 3-D ultrasound imaging would aid in objectively estimating the Pulse Wave Velocity (PWV) vector. This study aims to introduce a novel PWV estimation method along the propagation direction, validate it in phantoms and test its feasibility in vivo. A silicone vessel phantom consisting of a stiff and a soft segment along the longitudinal axis and and a silicone vessel with a plaque were constructed. A 2-D array with a center frequency of 2.5 MHz was used. Propagation was successfully visualized in 3-D in each phantom and in vivo in six healthy subjects. In three of the healthy subjects results were compared against conventional PWI using a linear array. PWVs were estimated in the stiff (3.42 ± 0.23 m · s−1) and soft (2.41 ± 0.07 m · s−1) phantom segments. Good agreement was found with the corresponding static testing values (stiff: 3.41 m · s−1, soft: 2.48 m · s−1). PWI-derived vessel compliance values were validated with dynamic testing. Comprehensive views of pulse propagation in the plaque phantom were generated and compared with conventional PWI acquisitions. Good agreement was found in vivo between the results of 4-D PWI (4.80 ± 1.32 m · s−1) and conventional PWI (4.28±1.20 m · s−1) (n = 3). PWVs derived for all of the healthy subjects (n = 6) were within the physiological range. Thus, 4-D PWI was successfully validated in phantoms and used to image the pulse wave propagation in normal human subjects in vivo.

Non-invasive Evaluation of Aortic Stiffness Dependence with Aortic Blood Pressure and Internal Radius by Shear Wave Elastography and Ultrafast Imaging

“…First of all, the probe can be not perfectly set across the artery, inducing an underestimation of the diameter. An ultrasonic 3D ultrafast image of the artery could be used to overcome this issue [32]- [34]. Finally, the method could provide two index to characterize the mechanical properties in arteries of patients in the clinic.…”

Receive/Transmit Aperture Selection for 3D Ultrasound Imaging with a 2D Matrix Transducer

“…Pulse wave imaging (PWI) is usually conducted based on two-dimensional (2D) images of the pulse wave propagation [10][11][12]. However, it is a 3D phenomenon, and elasticity of the carotid artery varies in different locations [6,13]. Consequently, 2D images impose limitations.…”

“…First, 2D elastography is sensitive to out-of-plane motion of the object, which can occur in carotid imaging [14]. Moreover, with conventional 2D ultrasound imaging, it is assumed that the propagation of the pulse wave is parallel to the imaging plane, which results in inaccuracies in PWV estimation [13]. A 3D assessment could be based on multiple cross-sectional 2D images of the 3D vessel structure, but it requires reproduction of the same imaging planes at later times, which is difficult [15].…”

“…A 3D assessment could be based on multiple cross-sectional 2D images of the 3D vessel structure, but it requires reproduction of the same imaging planes at later times, which is difficult [15]. Thus, it would be of great importance to have a comprehensive view of the arterial walls and generate a 3D elasticity map [13].…”

Quantitative Cardiac Output Assessment Using 4D Ultrafast Doppler Imaging: An in Vitro Study

“…The method relies on the emission of unfocused wave to insonifiate the entire medium in few transmits. Recently, ultrafast imaging was extended to 4D ultrasound imaging [5] for different applications: to image blood flow in small vessels [6], shear waves [7], pulse wave [8], quasi-static [9] and dynamic strain [10]. In the heart, 4D ultrasound ultrafast imaging was performed to image blood flow [5] and fibers [11] in the left ventricle of a human volunteer and tissue displacement in canine's hearts [10].…”