Advances in vascular anatomy and pathophysiology using high resolution and multiparametric sonography

Abstract

B-mode and Color Doppler are the first-line imaging modalities in cardiovascular diseases. However, conventional ultrasound (US) provides a lower spatial and temporal resolution (70-100 frames per second) compared to ultrafast technology which acquires several thousand frames per second. Consequently, the multiparametric ultrafast platforms manage new imaging algorithms as high-frequency ultrasound, contrast-enhanced ultrasound, shear wave elastography, vector flow, and local pulse wave imaging. These advances allow better ultrasound performances, more detailed blood flow visualization and vessel walls' characterization, and many future applications for vascular viscoelastic properties evaluation.In this paper, we provide an overview of each new technique's principles and concepts and the real or potential applications of these modalities on the study of the artery and venous anatomy and pathophysiology of the upper limb before and after creating a native or prosthetic arterio-venous fistula. In particular, we focus on high-frequency ultrasound that could predict cannulation readiness and its potential role in the venous valvular status evaluation before vascular access creation; on contrast-enhanced ultrasound that could improve the peri-operative imaging evaluation during US-guided angioplasty; on shear wave elastography and local pulse wave imaging that could evaluate preoperative vessels stiffness and their potential predictive role in vascular access failure; on vector flow imaging that could better characterize the different components of the vascular access complex flow.

Keywords: Multiparametric ultrasound; high-frequency ultrasound; local pulse wave velocity; shear wave elastography; vascular access; vector flow imaging.

Figure 1.

Cephalic vein valve and IMT evaluated with HFUS. Valve flaps are very well distinguishable (white arrows) and IMT (red line) is measurable at the far wall of the vessel.

Figure 2.

Longitudinal view of a cephalic vein in a distal radio-cephalic AVF using local SWE. The region of interest is adjusted to the IMT of the far wall of the vein. In this case the venous IMT is homogeneous with a stiffness of 47 kPa.

Figure 3.

Longitudinal view of the venous anastomosis in a prosthetic arteriovenous fistula using SWE, which shows the different elastic properties and stiffness of the vessel walls. The portion of the graft is much stiffer (represented in red) at the venous anastomosis than the contiguous venous walls.

Figure 4.

Longitudinal view of a radio-cephalic fistula using VFI, which represents the flow with many colored vectors frame. In this frame at the systolic peak it shows high velocity red vectors at the arterial side just before the fistula anastomosis, with recirculation and reverse flow (1), multidirectional low-velocity green vector against the venous wall on the venous side of the anastomosis (3) and faster vector streamline at the venous side of the fistula (2).

Figure 5.

Ultrafast measurement of the local PWV of the brachial artery. Ultrafast PWV measurements are obtained at the beginning of systole (BS) and the end of systole (ES). The region of interest is adjusted to the entire field of view of the transducer.