13/07/2022 - 11:00
Mapping pulsatile blood flow direction and velocity in the human tibial cortical bone with ultrasound
Sébastien Salles
Salle Modesty Blaise , la salle ce situe au Rez de Chaussée du bâtiment L. de Vinci
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Sébastien SALLES received the Masters degree in Electrical Engineering and the Masters degree in Acoustics from the Lyon National Institute of Applied Sciences (INSA Lyon) in 2012, and the PhD degree in 2015 for his research on the tissue motion estimation using ultrasound imaging at CREATIS (INSA Lyon). After three years post-doctoral position at NTNU, in Trondheim, focused on the detection of cardiac fibrosis, he returned in CREATIS for one year with a post-doctoral project focused on 3D ultrasound beamforming. He arrived at the  Laboratoire d’imagerie Biomédicale (LIB), in Paris, in 2019 for  a post-doctoral position on blood flow estimation in bone. He received ATIP Avenir grant in 2021 allowing him to build a new team focused on cardiac elastography.

résumé :

Intraosseous blood circulation is considered to be a key actor in bone growth and remodeling, bone metabolism, fracture healing and joint diseases. Yet our knowledge of intraosseous blood flow remains extremely scarce compared to other organs, because of a lack of suitable and accurate noninvasive investigation tools for its in vivo quantification.

     The in vivo assessment of intraosseous blood flow in humans has been attempted with dynamic contrast-enhanced magnetic resonance imaging and dynamic positron emission tomography. A drawback of these methods is their inability to measure the direction and pulsatile nature of blood flow. In addition to this, they rely on the slow perfusion of a contrast agent or radiotracer that is not confined to the vasculature.

Our team recently proved that ultrasound is capable of imaging inside the diaphysis of a long bone with a conventional clinical probe, unlike common belief. Capitalizing on this, we showed that ultrasound can measure the direction and velocity of pulsatile blood flow, after spatial averaging over the tibial cortex. Here, we now explore the feasibility of mapping pulsatile blood flow direction and velocity in the human tibial cortex with ultrasound.

Unlike traditional ultrasound imaging, our approach relies on the transmission of steered plane waves. Each image was reconstructed with a delay-and-sum algorithm that corrects for the effect of wave refraction at the outer surface of the tibia and wave speed anisotropy in cortical bone. After suppression of stationary signal in the images, pulsatile blood flow in cortical bone is revealed. Using a phase-based approach to estimate the motion between two consecutive images, blood flow velocity and direction was estimated at each pixel in the cortex of the tibia, and each instant of a 5 second acquisition.