Magnetic Fluid Detection Apparatus for Sentinel Lymph Node Identification
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for identifying sentinel lymph nodes, such as those using radioactive isotopes or magnetic fluids, face challenges like restricted use of radioactive materials, difficulty in distinguishing lymph nodes due to environmental noise, and the need for expensive and cumbersome high-sensitivity magnetic sensors, making them impractical for widespread use in sentinel lymph node biopsies.
Innovation Solution
A magnetic fluid detection method and apparatus that injects a paramagnetic fluid into tissues, applies a direct-current or alternating-current magnetic field to excite the fluid, and measures the local magnetic field gradient to identify areas of accumulation without external noise interference, using inexpensive sensors and allowing for quick and non-invasive identification of sentinel lymph nodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-sensitivity magnetic sensors (e.g., SQUID) are used to detect magnetic fluid, then measurement precision is improved, but device complexity and cost increase due to expensive shielding and complex cooling systems
Solution Approach 1:
The patent changes the detection parameter from direct magnetic field strength measurement to measurement of magnetic field gradient (spatial derivative). This parameter transformation allows using simpler sensors (Hall elements, magnetoresistive sensors) instead of complex SQUID systems, while still achieving sufficient detection sensitivity for clinical applications.
Solution Approach 2:
The patent replaces complex mechanical cooling systems (required by SQUID sensors operating at near-absolute zero temperatures) with electronic signal processing methods. By measuring magnetic field gradients at multiple positions and calculating differences, the system achieves high-sensitivity detection without requiring cryogenic cooling infrastructure.
2Reliability
If radioactive isotopes are used to identify sentinel lymph nodes, then identification reliability is improved, but safety concerns arise due to restricted use of radioactive materials
Solution Approach 1:
The patent uses paramagnetic fluids with short circulation half-lives (minutes to hours) instead of long-lived radioactive isotopes. The paramagnetic signal naturally decays as the fluid distributes and is cleared from the body, eliminating long-term radioactive exposure risks while maintaining sufficient detection window for surgical identification.
Solution Approach 2:
The patent introduces paramagnetic contrast agents as intermediaries that temporarily enhance magnetic field gradients in sentinel lymph nodes. These agents serve as safe alternatives to radioactive tracers, providing detectable signals during the surgical procedure without the harmful effects of ionizing radiation.
3Measurement precision
If magnetic fluid is injected into tissues to identify sentinel lymph nodes, then identification capability is improved, but external magnetic noise interferes with measurement accuracy
Solution Approach 1:
The patent divides the detection process into multiple spatial measurements taken at different positions around the target area. By measuring magnetic field gradients at multiple points and comparing differences, the system can distinguish localized signals from sentinel lymph nodes against background magnetic noise, effectively segmenting the signal from interference.
Solution Approach 2:
The patent converts the challenge of magnetic noise into an advantage by using differential measurement techniques. External magnetic noise affects all measurement points similarly, while the paramagnetic fluid creates localized gradient changes. By taking differences between measurements, the common-mode noise is rejected while the localized signal is enhanced.
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 reliable, rapid, and cost-effective identification of sentinel lymph nodes without radioactive isotopes, reducing the need for expensive shielding and complex cooling systems, and can be performed safely and efficiently during surgical operations.
Implementation Method 1
the specific magnetic permeability of a magnetic fluid possessing paramagnetism that has been injected into tissues is higher than that of the surrounding substance
Implementation Method 2
applying a direct-current or alternating-current magnetic field to the tissues constituting the object of measurement so that the magnetic fluid is excited
Implementation Method 3
measuring the local magnetic field gradient
Data Source
AI summary
The apparatus of the present invention comprises: an excitation device which excites the measurement site with a local direct-current or alternating-current magnetic field, and a plurality of magnetic field detection devices which are disposed in proximity to each other to measure the magnetic field component that is perpendicular to the exciting magnetic field. A magnetic fluid that possesses paramagnetism is injected from the outside into a substance in which a fluid can flow, and the local magnetic field gradient is then measured while the injected magnetic fluid is excited by the application of a direct-current or alternating-current magnetic field from the outside, thus measuring the presence or absence of distortion of the local magnetic field distribution arising from the fact that the specific magnetic permeability of the magnetic fluid injected into the substance is higher than that of the surrounding substance, so that sites where large amount of the magnetic fluid has accumulated are identified in a non-invasive manner without being affected by external magnetic noise.