Arotic Evans blue dye accumulation: its measurement and interpretation

Area of Science:

• Biomedical Engineering
• Physiology
• Optical Imaging

Background:

• Parenteral Evans blue dye (EBD) binds to albumin, serving as an indicator for transvascular protein flux.
• Quantifying protein flux is crucial for understanding vascular permeability and related pathologies.

Purpose of the Study:

• To develop and validate a model relating arterial surface EBD accumulation to reflected light intensity.
• To establish a non-invasive method for assessing transvascular protein flux.

Main Methods:

• A mathematical model was created to correlate EBD accumulation (M) with optical absorbance (rho) derived from reflected light intensities (I/I0).
• Model validity was assessed by comparing predicted and measured optical absorption coefficients for EBD.
• Model predictions of vessel wall stretch were compared against directly measured area changes.

Main Results:

• The model equation M = 3.92 rho + 0.80 rho3 accurately describes EBD accumulation.
• Predicted optical absorption coefficient (0.128 cm2 nmol-1) closely matched the measured value (0.125 cm2 nmol-1).
• Predicted percentage area changes showed a strong linear correlation (R=0.994) with measured changes (Y = 0.09 + 1.01X).

Conclusions:

• The developed model provides a valid and accurate method for quantifying transvascular protein flux using EBD and optical measurements.
• This technique offers a promising approach for in vivo assessment of vascular permeability.
• The model's ability to predict vessel wall mechanics further validates its utility in physiological studies.