A mathematical model for velocity-selective arterial spin labeling.

Area of Science:

• Medical Imaging
• Biophysics
• Physiological Modeling

Background:

• Velocity selective arterial spin labeling (VSASL) is an advanced neuroimaging technique.
• Accurate quantification in VSASL relies on precise modeling of arterial blood flow.
• Existing models may not fully capture the complexities of velocity-dependent labeling and saturation.

Purpose of the Study:

• To develop a rigorous theoretical framework for velocity selective arterial spin labeling (VSASL).
• To define and analyze key concepts and quantities essential for VSASL.
• To provide a foundation for improving VSASL accuracy and experimental design.

Main Methods:

• Derived an expression for the VSASL arterial delivery function.
• Incorporated velocity and acceleration profiles within the vascular system.
• Analyzed labeling efficiency, effective bolus width, and timing requirements.

Main Results:

• Predicted a flow-dependent negative bias in effective bolus width with combined velocity selective inversion (VSI) and velocity selective saturation (VSS).
• Identified that this bias can be mitigated by adjusting cutoff velocities between VSI and VSS modules.
• Quantified the dependence of labeling efficiency on arterial delivery function characteristics.

Conclusions:

• The developed theoretical framework is general and adaptable to future advancements in VSASL.
• The model offers critical insights for understanding and characterizing VSASL performance.
• This work can guide the design of improved VSASL experiments and novel techniques.