Intralipid Contrast Agent for Capillary Blood Flow Imaging
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Solution Overview
Problem
Current methods for imaging blood flow in capillaries, such as Optical Doppler Tomography (ODT), face challenges in detecting minute microcirculation and quantitatively imaging capillary blood flow due to low sensitivity and difficulty in distinguishing between different types of microvasculature, especially in highly scattering media like the brain.
Innovation Solution
Intralipid is injected into the bloodstream to enhance imaging by generating a Doppler frequency shift with a laser beam, allowing for the creation of three-dimensional tomographic images and calculating blood flow velocity, thereby improving the sensitivity and accuracy of capillary flow detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional ODT methods are used to image capillary blood flow, then the imaging can be performed without contrast agents, but the sensitivity is insufficient to detect minute microcirculation and distinguish different types of microvasculature
Solution Approach 1:
Intralipid is introduced as an intermediary contrast agent that mediates between the imaging system and the blood flow being imaged. The lipid microparticles in Intralipid serve as additional scattering centers that enhance the Doppler signal from capillary blood flow, enabling detection of minute microcirculation that would otherwise be below the detection threshold of conventional ODT methods
Solution Approach 2:
The invention changes the optical scattering parameters of the blood by introducing Intralipid, which contains lipid microparticles with specific size distributions (0.03-20 μm). This parameter change enhances the Doppler frequency shift signals from capillary flows, improving the measurement precision of blood flow velocity and flow direction detection in previously undetectable microvasculature
2Reliability
If red blood cells are used as the sole scattering particles for Doppler detection, then the method remains noninvasive, but the latency between red blood cells passing through the detection volume limits continuous flow detection
Solution Approach 1:
Intralipid provides continuous Doppler signals by introducing a high concentration of lipid microparticles that continuously scatter laser light as they flow through the detection volume. This eliminates the gaps in the Doppler signal that occur when using only red blood cells, as the lipid microparticles are present in much higher concentrations and provide uninterrupted scattering events, enabling continuous monitoring of blood flow velocity and direction
Solution Approach 2:
The lipid microparticles in Intralipid act as artificial scattering particles that copy the Doppler scattering function of red blood cells. These microparticles mimic the light-scattering behavior of RBCs but are present in sufficient concentrations to provide continuous signals, effectively creating a surrogate scattering medium that maintains the noninvasive nature of the imaging while solving the latency problem
3Measurement precision
If high spatial resolution is achieved in ODT for imaging tissue structure, then the ability to image both structure and flow is improved, but the detection of minute microcirculation remains challenging in highly scattering media
Solution Approach 1:
The invention enhances the optical contrast in highly scattering media by introducing Intralipid, which modifies the scattering properties of the blood. The lipid microparticles create additional scattering centers that increase the Doppler signal strength from capillary flows, effectively changing the optical interaction characteristics to improve detection of minute microcirculation while maintaining the high spatial resolution structural imaging capability of ODT
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method significantly enhances the detection and quantification of capillary flow, maintaining sensitivity and accuracy for physiological and pharmacological studies, and effectively differentiates between tumor and non-tumor microvasculature, with intralipid providing continuous Doppler signals that overcome the limitations of red blood cell latency.
Implementation Method 1
applying a laser beam to the specific site so as to generate a Doppler frequency shift of the laser caused by the intralipid flowing through the blood vessels at the specific site
Implementation Method 2
ODT is an optical technique for imaging both the tissue structure and the flow velocity of moving particles in highly scattering media
Data Source
AI summary
The present invention provides a method of imaging blood vessels or blood flow in blood vessels in an animal comprising:(i) injecting a lipid solution into the bloodstream of the animal;(ii) imaging the blood vessels by an imaging method; and(iii) calculating the blood flow velocity in the blood vessels.