MRI Blood Flow Detection Using Modulated Magnetic Fields
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Solution Overview
Problem
Current MRI systems lack a non-invasive method to continuously detect blood flow within the MR scanner environment, which is crucial for accurate non-contrast MR angiography, as existing methods rely on estimated trigger times or free-running sequences, and mechanical sensors are not effective for continuous blood flow measurement.
Innovation Solution
A method and system using a modulated magnetic field generated by a generator coil, with frequencies measurable by the MRI's RF reception system, to differentiate blood flow from other movements by analyzing response signals from multiple RF antennae, employing blind and semi-blind source separation techniques like Independent Component Analysis to isolate the flow component.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If mechanical sensors or electrodes are used to measure patient movements, then motion artifacts can be detected, but continuous non-invasive blood flow detection is not achieved
Solution Approach 1:
The patent applies multi-functionality by using the existing RF reception system of the MRI scanner to perform both its original function of receiving MR signals and the additional function of detecting blood flow through pilot tone analysis. The same RF antennae and receiver coil are utilized to detect both MR signals and changes in the pilot tone caused by blood flow, eliminating the need for separate dedicated sensors and enabling continuous non-invasive blood flow monitoring.
Solution Approach 2:
The patent introduces a pilot tone signal as an intermediary carrier that mediates between the MRI system and the blood flow measurement. The pilot tone is transmitted through the body and its changes are caused by blood flow, allowing the MRI's RF system to indirectly detect blood flow parameters without direct contact with the blood or invasive sensors.
2Productivity
If the RF reception system is used to detect both MR signals and blood flow, then continuous blood flow detection is enabled, but signal separation becomes complex
Solution Approach 1:
The patent applies segmentation by separating the detection of different signals into distinct frequency domains. The pilot tone is transmitted at a specific frequency that is modulated by blood flow, while MR signals operate at different frequencies. This frequency-based segmentation allows the RF reception system to simultaneously capture both types of signals and enables straightforward separation through frequency filtering and spectral analysis, reducing processing complexity despite the dual-function requirement.
Solution Approach 2:
The patent uses partial action by selectively analyzing only the specific frequency components of the RF signals that correspond to the pilot tone modulation. Rather than processing the entire RF signal spectrum, the system focuses on extracting and analyzing only the relevant pilot tone frequency components that contain blood flow information, thereby simplifying the signal processing while maintaining continuous detection capability.
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
Enables continuous and accurate detection of blood flow, reducing noise artifacts and improving the precision of blood flow measurement in MRI systems by distinguishing flow-induced changes from cardiac and respiratory movements.
Implementation Method 1
a magnetic resonance imaging system with a generator coil and a receiver coil, wherein the generator coil generates a modulated magnetic field
Implementation Method 2
differentiate blood flow from other movements by analyzing response signals from multiple RF antennae
Data Source
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AI summary
The invention describes a method for measuring blood flow comprising the following steps: - generating a modulated magnetic field (M) by a generator coil (20), - recording response signals (S1, S2) of the modulated magnetic field (M) from an object (O) with an RF reception system (7, 21, 17), wherein the response signals (S1, S2) are measured by at least two RF antennae (21) of the RF reception system (7, 21, 17), - separating a flow component of the recorded response signals (S1, S2) from those signal components resulting from movements of the object (O). The invention further describes a system for blood flow measurement, a control unit and a magnetic resonance imaging system.