Mapping mean and fluctuating velocities by Bayesian multipoint MR velocity encoding-validation against 3D particle...

Area of Science:

• Cardiovascular Imaging
• Biomedical Engineering
• Fluid Dynamics

Background:

• Accurate measurement of blood flow dynamics is crucial for understanding cardiovascular diseases.
• Particle tracking velocimetry (PTV) is a reference standard for velocity measurements but is invasive.
• Magnetic resonance imaging (MRI) offers non-invasive flow assessment, but speed and accuracy for complex flows remain challenges.

Purpose of the Study:

• To validate Bayesian multipoint MR velocity encoding against PTV for measuring velocity vector fields and fluctuating velocities.
• To assess the accuracy of accelerated MR methods in a realistic aortic arch model with stenosis.

Main Methods:

• Utilized an elastic cast of a human aortic arch with simulated stenosis.
• Employed a pulsatile pump to generate physiological flow conditions, including high velocities and turbulence.
• Acquired velocity data using Bayesian multipoint MR velocity encoding and PTV in the ascending aorta.

Main Results:

• MR velocity encoding showed excellent correlation with PTV for both velocities (r(2) = 0.98) and turbulent kinetic energies (r(2) = 0.98).
• Mean differences were small (-4.8 ± 13.3 cm/s for velocity, -21.8 ± 53.9 J/m(3) for TKE).
• Agreed well in mapping 3D velocity patterns downstream of stenoses and regions of high velocity fluctuations.

Conclusions:

• Accelerated Bayesian multipoint MR velocity encoding is an accurate method for assessing mean and fluctuating velocities.
• The MR technique provides a non-invasive, reliable alternative to PTV for cardiovascular flow analysis.
• This MR method has significant potential for clinically feasible velocity mapping in under 15 minutes.