Cerebral capillary velocimetry based on temporal OCT speckle contrast

Area of Science:

• Biomedical Optics
• Neuroscience
• Medical Imaging

Background:

• Assessing cerebral microcirculation is crucial for understanding brain function and disease.
• Optical Coherence Tomography (OCT) is a non-invasive imaging technique with potential for hemodynamic monitoring.
• Current methods for measuring capillary blood flow in the brain have limitations.

Purpose of the Study:

• To introduce and validate a novel OCT-based method for measuring single red blood cell (RBC) velocities in rodent brain capillaries.
• To establish a relationship between OCT-derived speckle decorrelation time and RBC flow velocity.
• To demonstrate the applicability of the method for in vivo brain hemodynamics assessment.

Main Methods:

• Utilized quantitative laser speckle contrast analysis on temporal OCT speckle signals to estimate speckle decorrelation rate.
• Acquired M-mode B-frames using a high-speed OCT system on a capillary flow phantom and in vivo mouse brain.
• Analyzed time-varying OCT signals to derive capillary velocities based on the decorrelation time and velocity relationship.

Main Results:

• Demonstrated an inverse relationship between estimated decorrelation time and absolute RBC velocity in a flow phantom.
• Successfully applied the OCT method to measure capillary hemodynamics in vivo in the mouse brain.
• The proposed OCT velocimetry provides quantitative hemodynamic information complementary to OCT angiography.

Conclusions:

• The developed OCT capillary velocimetry method accurately measures RBC velocities in rodent brain capillaries.
• This technique offers a valuable tool for quantitative assessment of microcirculatory flow in the brain.
• The method has the potential to enhance our understanding of brain hemodynamics in health and disease.