A perfusion phantom for ASL MRI based on impinging jets

Area of Science:

• Medical Imaging
• Fluid Dynamics
• Biophysics

Background:

• Arterial Spin Labeling (ASL) MRI is crucial for non-invasively measuring brain perfusion.
• Validation of ASL methods requires reliable phantoms that accurately mimic physiological conditions.
• Existing phantoms may not fully capture the complexities of blood flow and mixing.

Purpose of the Study:

• To develop and validate a novel perfusion phantom for ASL perfusion MRI.
• To assess the phantom's ability to simulate perfusion-like mixing and signal changes.
• To evaluate the phantom's utility for testing ASL sequences and protocols.

Main Methods:

• A perfusion phantom utilizing impinging jets and a peristaltic pump was designed.
• ASL-MRI data were acquired using pseudo-continuous ASL sequences with 3D stack-of-spirals and 2D EPI readouts.
• Varying pump rates and post-labeling delays were employed to validate the phantom.

Main Results:

• Fluid dynamics simulations predicted optimal mixing within the phantom's central axis.
• Experimental data showed reproducible signal changes consistent with the Buxton kinetic model.
• Calculated perfusion rates closely matched the volumetric flow rates from the pump, with no observed label outflow.

Conclusions:

• The novel impinging jet phantom effectively simulates perfusion-like conditions and well-mixed compartments.
• The phantom provides reproducible perfusion and transit time values within the physiological range.
• This phantom design offers significant potential for ASL MRI research and clinical applications.