Intravascular Flow Measurement via OCT Backscattering Contrast
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Solution Overview
Problem
Current methods for determining intravascular blood flow rates are limited by the inability to accurately measure flow velocities due to the dynamic angle of Doppler ultrasound probes and the lack of reliable coronary flow reserve measurements, which also fail to provide structural information about blood vessels.
Innovation Solution
An optical coherence tomography (OCT) or optical frequency-domain imaging (OFDI) system is used to perform cross-sectional imaging of blood vessels, delivering a differential-contrast fluid to determine flow velocities and rates by analyzing scattered light, combined with a catheter system for precise fluid delivery and data collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If intravascular Doppler ultrasound is used to measure blood flow, then flow velocity measurement is possible, but measurement precision deteriorates due to unknown and dynamically changing probe angles
Solution Approach 1:
The patent replaces the mechanical Doppler ultrasound system with an optical coherence tomography (OCT) system that uses light scattering from blood cells to measure flow velocity. This substitution eliminates the angle dependency problem because the OCT system measures the Doppler shift of backscattered light, which is insensitive to the probe angle relative to the vessel axis.
Solution Approach 2:
The patent changes the measurement parameter from acoustic wave frequency shift (Doppler ultrasound) to optical wave frequency shift (OCT). This parameter change allows for more precise flow velocity measurement because optical wavelengths are smaller and provide higher resolution, and the optical Doppler effect in OCT is less sensitive to angle variations.
2Measurement precision
If thermodilution techniques are used to determine blood flow rate, then flow rate measurement is possible, but reliability deteriorates because only a quantity proportional to flow rate can be determined, not the actual flow rate
Solution Approach 1:
The patent replaces the thermodilution technique with an optical backscattering method. Instead of measuring temperature changes of injected saline, the system uses OCT to directly measure the velocity of blood cells through optical Doppler effects. This substitution provides direct flow rate measurement without requiring proportionality constants or calibration factors.
Solution Approach 2:
The patent enables the blood itself to serve as the measurement medium. The natural backscattering of light from blood cells is utilized to measure flow velocity directly, eliminating the need for external indicators (such as temperature-changed saline in thermodilution) and the complex calculations required to convert indicator dilution to flow rate.
3Measurement precision
If continuous thermodilution is used to measure blood flow rate, then accurate flow rate determination is possible under vasodilation conditions, but adaptability deteriorates because baseline conditions cannot be accurately measured
Solution Approach 1:
The patent creates a universal measurement system that can accurately measure blood flow under all conditions (baseline, vasodilation, stress) without requiring different measurement protocols. The optical backscattering method works independently of vessel diameter changes or flow rate changes, providing consistent accuracy across all physiological states, unlike continuous thermodilution which is condition-specific.
4Measurement precision
If thermodilution catheters are used for flow measurement, then flow rate determination is possible, but device complexity increases and imaging capability is lost due to catheter size
Solution Approach 1:
The patent merges the flow measurement function with the imaging function in a single OCT system. The same optical catheter that provides high-resolution intravascular imaging also performs flow velocity measurement through optical Doppler effects. This integration eliminates the need for separate thermodilution catheters and allows simultaneous acquisition of both structural and functional data.
Solution Approach 2:
The OCT catheter serves multiple functions: it provides high-resolution cross-sectional imaging of the vessel wall and lumen, measures blood flow velocity through optical Doppler effects, and can characterize tissue properties. This multi-functionality in a single device reduces overall system complexity and enables comprehensive assessment in one procedure.
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
This approach allows for accurate determination of intravascular flow velocities and rates while enabling simultaneous imaging, overcoming the limitations of existing techniques and providing structural information about vessel conditions.
Implementation Method 1
determining flow velocities and flow rates based on velocity measurements obtained using backscattering contrast
Implementation Method 2
Usage of the Doppler Effect in optical technologies, such as optical coherence tomography
Data Source
AI summary
An apparatus including: an imaging system; a probe for insertion into a vessel, the probe being coupled to the imaging system; a flow delivery system associated with the probe to release a differential-contrast fluid into the vessel at a location proximal to an end of the probe; and a processor to: collect data from the imaging system based on release of the differential-contrast fluid into the vessel, analyze the collected data to identify a presence or absence of the differential-contrast fluid as a function of time, and determine a flow rate in the vessel based on analyzing the collected data.