3D measurements of blood flow and biomarker calculation

4D flow MRI provides 3D measurements of blood flow in the human body and calculates bio-markers such as blood flow in vessels, the friction produced by the blood against the vessel walls, blood pressure, pulse wave velocity or eddies formed in certain vessels.
A biomarker is a physical or chemical feature that can help identify and track a pathology quantitatively so as to speed up diagnosis and improve patient management. The low spatial resolution of 4D flow MRI limits its clinical applications, restricting examinations to larger vessels for now and posing still significant challenges for the calculation of bio-markers.

The test bench developed at LHEEA is a Mock Circulation Loop (MCL) which comprises a "vascular ghost " and a kind of artificial heart, precisely reproducing the pulsatile flow conditions of circulation in the vessels. The system was used to validate the 4D flow MRI measurements and a new post-processing algorithm of these measurements, by comparing the velocity and friction results obtained by medical imaging with those obtained on the test bench using Laser Doppler Velocimetry (LDV), a high-precision technique.

For MRI measurements a box - containing a gel that simulates human tissue - is positioned around the ghost. The fluid is a mixture of water and glycerol, which reproduces the physical properties of the blood.

These trials were conducted as part of a PhD thesis supervised by David Le Touzé (LHEEA - Research Laboratory in Hydrodynamics, Energetics & Atmospheric Environment – Centrale Nantes/CNRS), Jean-Michel Serfaty (Institut du Thorax and Nantes University Hospital) and Félicien Bonnefoy (LHEEA – Centrale Nantes/CNRS).