Fluid equations applied to blood flow measurement using digital videodensitometry.

Area of Science:

• Medical Imaging
• Fluid Dynamics
• Biomedical Engineering

Background:

• Accurate measurement of time-dependent fluid flow is essential in vascular imaging.
• Traditional methods often rely on bolus tracking, which can be complex and introduce errors.
• Developing non-invasive techniques for flow quantification is a significant clinical need.

Purpose of the Study:

• To compute time-dependent fluid flow from projection radiographs using fundamental fluid equations.
• To validate a novel algorithm that avoids the need for bolus tracking.
• To assess the accuracy and limitations of the proposed flow computation method.

Main Methods:

• Combined and integrated fluid equations of continuity and incompressibility to derive an instantaneous mass conservation equation.
• Applied the technique to phantom data and patient data acquired via digital subtraction angiography (DSA).
• Evaluated flow rate and velocity computations based on image sequences with varying fluid displacements.

Main Results:

• Successfully computed instantaneous and mean flow rates from DSA image sequences.
• Demonstrated computation of velocities within 13% uncertainty in a phantom study.
• Achieved agreement within 16% for mean flow rates from multiple angiographic projections.

Conclusions:

• The developed technique effectively computes time-dependent flow rates from DSA sequences, even with significant frame-to-frame fluid movement.
• Accuracy is highly influenced by the contrast density gradient magnitude.
• This method offers a promising approach for non-invasive vascular flow assessment.