MRI Table Motion Sensor Using Self-Resonant Spiral Coil
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Solution Overview
Problem
Traditional respiration monitoring systems for MRI are uncomfortable for patients, require additional clinician time for setup, and prior contactless motion detection systems are unreliable due to limited sensitivity and magnetic field strength, especially for patients with abnormal breathing patterns or larger body sizes.
Innovation Solution
A contactless motion sensor system integrated into the MRI table, utilizing a self-resonant spiral coil and coupling loop to generate and detect a magnetic field, allowing for reliable respiration signal measurement without patient contact or additional setup, with sensors positioned to detect torso motion effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional bellows sensors are used for respiratory monitoring, then respiration waveforms can be detected, but patient comfort deteriorates and additional clinician time is required for setup
Solution Approach 1:
The patent replaces mechanical bellows sensors with a contactless electromagnetic motion sensor system. The sensor uses magnetic field interaction with the patient's torso to detect respiratory motion, eliminating the need for physical contact and manual setup while maintaining detection capability
Solution Approach 2:
The sensor system automatically detects and processes respiratory motion without requiring clinician intervention for sensor placement or calibration. The system self-calibrates and begins monitoring immediately upon activation, eliminating setup time requirements
2Ease of operation
If contactless motion detection systems are used, then patient comfort is improved, but reliability deteriorates due to limited sensitivity and magnetic field strength
Solution Approach 1:
The patent employs a self-resonant spiral coil that operates at a predefined resonant frequency to generate a magnetic field with enhanced strength and penetration depth. This resonant frequency operation allows the sensor to detect subtle motion variations in patients with abnormal breathing patterns and larger body sizes
Solution Approach 2:
The sensor detects respiratory motion by measuring changes in the magnetic field caused by torso movement during respiration. The system captures these subtle vibrations and converts them into electrical signals for analysis, enabling reliable detection of respiratory waveforms
3Ease of operation
If prior contactless motion detection systems are used, then ease of operation is improved, but measurement precision deteriorates for patients with abnormal breathing patterns or larger body sizes
Solution Approach 1:
The sensor system uses a self-resonant spiral coil operating at a specific resonant frequency to generate a magnetic field with enhanced penetration depth and strength. This allows accurate detection of motion in patients with larger body sizes and abnormal breathing patterns that previous systems could not reliably measure
Solution Approach 2:
The magnetic field acts as an intermediary between the sensor and the patient's torso, transmitting motion information without direct contact. The resonant magnetic field penetrates tissue effectively to detect subtle motion variations, serving as a reliable mediator for measuring respiratory motion in diverse patient populations
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 system provides accurate and comfortable respiration monitoring with increased sensitivity and depth of penetration, reducing image degradation from patient motion and eliminating the need for clinician-assisted sensor placement, suitable for various patient positions and breathing styles.
Implementation Method 1
A driver-receiver is coupled to the SRS coil and configured to generate the drive signal to excite the SRS coil and to receive an RF signal from the SRS coil
Implementation Method 2
The motion sensor includes a self-resonant spiral (SRS) coil excited by a drive signal to radiate a magnetic field having a predefined resonant frequency
Implementation Method 3
The coupling loop is inductively coupled to the SRS coil and configured to generate a drive RF signal to excite the SRS coil and receive a reflection RF signal from the SRS coil
Implementation Method 4
A controller is configured to detect patient motion based on the reflection RF signal
Data Source
AI summary
A table for an MRI system includes a top surface for supporting a patient being imaged and a motion sensor for sensing motion of the patient. The motion sensor is located below the top surface and includes a self-resonant spiral (SRS) coil and a coupling loop. The coupling loop generates a drive RF signal to excite the SRS coil to radiate a magnetic field having a predefined resonant frequency. The coupling loop also receives a reflection RF signal from the SRS coil. The motion sensor is located such that at least a portion of a torso of the patient being imaged is within the magnetic field. A controller is configured to detect patient motion based on the reflection RF signal.