Medical Image Processing for Vascular Wall Shear Stress
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Solution Overview
Problem
Conventional MRI techniques for calculating wall shear stress (WSS) face challenges due to low spatial resolution in four-dimensional image data from 4D Flow, making it difficult to accurately identify vascular wall regions and resulting in reduced calculation accuracy of WSS.
Innovation Solution
A medical image processing apparatus and method that calculates fluid information and identifies vascular wall regions based on three-dimensional phase image data from phase contrast MRI, using processing circuitry to set a region of interest, apply filtering, and generate gradient vector maps to accurately determine the vascular wall region for precise WSS calculation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If four-dimensional image data from 4D Flow is used to calculate velocity vector data, then non-invasive blood flow information can be obtained, but the low spatial resolution makes it difficult to accurately identify vascular wall regions
Solution Approach 1:
The patent combines high-resolution anatomical image data with four-dimensional flow data to create composite images that display both vascular structure and blood flow information. This merging allows accurate identification of vascular wall regions from the high-resolution anatomical data while maintaining the functional flow information from the 4D Flow data, thereby resolving the contradiction between spatial resolution and measurement precision.
Solution Approach 2:
The patent uses an intermediary processing step that overlays or fuses the low-resolution velocity vector data with high-resolution anatomical images. This intermediary composite representation allows the system to leverage the spatial accuracy of anatomical images for vascular wall identification while preserving the hemodynamic information from the flow data, thus overcoming the spatial resolution limitation.
2Manufacturing precision
If high-resolution image data is obtained by separate scanning, then detailed vascular structure can be visualized, but changes in vascular wall region caused by cardiac cycles cannot be captured
Solution Approach 1:
The patent merges separately acquired high-resolution anatomical images with four-dimensional flow data that contains temporal information across cardiac cycles. The fusion process integrates the spatial detail from anatomical scanning with the temporal dynamics from phase-contrast MRI, producing composite images that simultaneously display static vascular structure and dynamic blood flow changes throughout the cardiac cycle.
Solution Approach 2:
The patent adds the time dimension to the high-resolution anatomical data by incorporating four-dimensional (three spatial dimensions plus time) flow information. This dimensional expansion allows the system to visualize not only the detailed vascular structure but also the temporal variations in blood flow and vascular wall position across multiple cardiac phases, thereby recovering the temporal information that would be lost in static high-resolution imaging.
3Measurement precision
If conventional techniques use separate scans for high-resolution vascular imaging and flow measurement, then detailed anatomy can be obtained, but calculation accuracy of WSS is reduced due to inability to capture cardiac cycle changes
Solution Approach 1:
The patent merges two separate imaging protocols (high-resolution anatomical scanning and phase-contrast flow imaging) into a unified workflow where the data from both scans are integrated and co-registered. This combination allows the system to utilize the anatomical precision for accurate vascular wall localization and the flow data for velocity measurement, thereby improving WSS calculation accuracy while presenting a streamlined integrated solution to users.
Solution Approach 2:
The patent creates a multi-functional imaging system that can perform both high-resolution anatomical visualization and four-dimensional flow measurement, and combines these functions in post-processing. The system serves multiple purposes: visualizing vascular structure, measuring blood flow dynamics, identifying vascular wall regions, and calculating WSS, all within a single integrated workflow that reduces the practical complexity despite combining multiple imaging capabilities.
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 solution improves the accuracy of WSS calculation by enhancing the identification of vascular wall regions, leading to more precise fluid information and vascular information, thereby improving the overall calculation accuracy of WSS.
Implementation Method 1
A magnetic resonance imaging (MRI) apparatus is an imaging apparatus which excites nuclear spins in a patient placed in a static magnetic field with a radio frequency (RF) signal of Larmor frequency and thereby generates an image by reconstructing a magnetic resonance signal generated from the patient as a result of the excitation
Implementation Method 2
4D Flow uses a technique which is called a phase contrast method and is capable of measuring flow velocity as a phase
Data Source
AI summary
A medical image processing apparatus according to one of present embodiments includes processing circuitry. The processing circuitry is configured to calculate fluid information including a velocity vector based on three-dimensional phase image data in multiple time phases, the three-dimensional phase image data being collected by phase contrast magnetic resonance imaging, and the three-dimensional phase image data representing a fluid flowing through a lumen. The processing circuitry is configured to identify a wall region of the lumen based on the velocity vector. The processing circuitry is configured to calculate wall shear stress using the wall region and the fluid information.