Phase contrast MRI of creeping flows using stimulated echo

Area of Science:

• Biomedical Engineering
• Medical Imaging
• Fluid Dynamics

Background:

• Creeping flows are vital in physiological processes, including tumor interstitial fluid flow and brain glymphatic flow.
• Current non-invasive methods struggle to measure slow flows in optically opaque tissues in vivo.
• Existing phase-contrast MRI (PC-MRI) is limited by diffusion weighting and hardware imperfections for slow flow quantification.

Purpose of the Study:

• To develop a novel PC-MRI technique capable of measuring very slow physiological flows non-invasively.
• To overcome the limitations of conventional PC-MRI in quantifying slow fluid dynamics in biological tissues.
• To validate the new technique for measuring flows in the micrometer-per-second range.

Main Methods:

• Development of a new PC-MRI technique incorporating stimulated echo preparation.
• Validation using controlled water flow experiments in a pipe at 4.7 Tesla.
• Application of the technique to observe natural convection flows in liquids within a magnet.

Main Results:

• Successfully measured flows as slow as 1 micrometer per second.
• Achieved less than 10% error in flow rate measurements compared to controlled flow.
• Captured and characterized the exponential decay of natural convection flows over time.

Conclusions:

• The developed PC-MRI method enables accurate non-invasive measurement of slow, creeping flows in vivo.
• This technique holds significant potential for studying physiological phenomena like tumor and brain fluid dynamics.
• The method overcomes previous limitations, paving the way for new research in microfluidics within biological tissues.