Blood Flow Measurement Using Alternating OCT Cross Sections
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Solution Overview
Problem
Conventional blood flow measurement techniques using optical coherence tomography (OCT) are time-consuming and prone to reliability issues due to the need for separate measurements of blood vessel orientation and Doppler OCT, which can be affected by object movement, especially in living subjects like the eye.
Innovation Solution
A blood flow measurement apparatus that alternately performs first and second scans of intersecting cross sections using OCT, generating blood flow information by calculating the gradient of the blood vessel based on phase images and specified regions, thereby reducing measurement time and improving reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate measurements for blood vessel orientation estimation and Doppler OCT are performed, then measurement precision is improved, but measurement time is prolonged
Solution Approach 1:
The patent combines blood vessel orientation estimation and Doppler OCT measurements into a single integrated measurement process. The apparatus performs both functions simultaneously by acquiring OCT data from multiple cross-sections and processing them together, eliminating the need for separate measurement sessions and thereby reducing total measurement time while maintaining measurement precision.
Solution Approach 2:
The patent performs preliminary acquisition of OCT data from multiple cross-sections (including both the measurement cross-section and reference cross-sections) before actual blood flow analysis. This preliminary data collection enables simultaneous orientation estimation and Doppler analysis without requiring additional measurement time, as all necessary data is gathered in advance during the initial scanning phase.
2Measurement precision
If Doppler OCT is performed over a sufficient period for blood flow information collection, then measurement precision is improved, but object movement during measurement deteriorates reliability
Solution Approach 1:
The patent divides the measurement into multiple independent cross-sections (measurement cross-section and multiple reference cross-sections). Each cross-section can be processed independently for orientation estimation, and the segmentation allows the system to select or combine results from different sections, reducing the impact of movement artifacts in any single section while maintaining overall measurement precision.
Solution Approach 2:
The patent acquires OCT data from reference cross-sections that serve as copies or alternatives to the primary measurement cross-section. If movement affects the measurement cross-section, the reference cross-sections provide backup data that can be used instead, thereby maintaining reliability without requiring excessively long measurement periods.
3Loss of time
If multiple cross sections are scanned alternately, then measurement time is shortened, but device complexity increases
Solution Approach 1:
The patent makes the OCT apparatus multi-functional by enabling it to perform both orientation estimation and blood flow velocity measurement using the same hardware infrastructure. The scanning system is designed to acquire data from multiple cross-sections that serve dual purposes: defining vessel orientation and measuring Doppler shifts, thereby shortening measurement time without requiring separate dedicated devices for each function.
Solution Approach 2:
The patent transitions from single-cross-section measurement to multi-cross-section measurement by adding spatial dimensionality to the scanning approach. Instead of repeatedly scanning one cross-section, the system scans multiple cross-sections at different positions, utilizing the spatial arrangement of these sections to simultaneously determine orientation and measure flow, thus reducing measurement time while managing complexity through systematic spatial sampling.
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 apparatus significantly shortens measurement time and enhances the reliability of blood flow information by simultaneously scanning multiple cross sections and calculating the blood vessel gradient, minimizing the impact of object movement.
Implementation Method 1
an OCT unit configured to perform optical coherence tomography
Implementation Method 2
the blood flow information is determined based on the Doppler frequency shift
Data Source
AI summary
A scanner of a blood flow measurement apparatus of an embodiment alternately performs first scan and second scan for first and second cross sections both intersecting an interested blood vessel. An image forming unit forms one or more images of the first cross section including a phase image of the first cross section and an image of the second cross section. A blood vessel region specification unit specifies a first blood vessel region in any of the one or more images of the first cross section and a second blood vessel region in the image of the second cross section. A gradient calculation unit calculates a gradient of the interested blood vessel at the first cross section based on the first and second blood vessel regions. A blood flow information generation unit generates blood flow information based on the phase image and the gradient.