Low-Field MRI Using SQUID Detection and Field Cycling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional MRI systems at high magnetic fields cause claustrophobia and image quality issues due to noise, while lower field systems suffer from poor signal quality and image resolution, and existing SQUID-based methods face challenges with pre-polarizing pulses and interference susceptibility.
Innovation Solution
An MRI system using a resonant input at a median field range above 100 gauss, cycling the main field to a low field after a 90-degree pulse to develop T1 differences, with a SQUID-based detection method and superconducting coils to generate a field of 100 to 300 gauss, allowing for enhanced T1 contrast and reduced noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high magnetic field (1 Tesla or more) is used for MRI, then polarisation of hydrogen nuclei and signal strength are improved, but patient comfort deteriorates due to claustrophobia and noise
Solution Approach 1:
The patent changes the operating magnetic field parameter from conventional high field (1 Tesla or more) to low field (2,000-3,000 gauss or 0.2-0.3 Tesla). This parameter change reduces the polarisation and signal strength but improves patient comfort by eliminating claustrophobia and reducing noise from gradient coils
Solution Approach 2:
The patent introduces a SQUID (Superconducting Quantum Interference Device) as an intermediary detection system. The SQUID acts as a highly sensitive mediator that can detect the weak NMR signals at low fields with adequate signal-to-noise ratio, enabling low-field MRI to function effectively
2Object-affected harmful factors
If low magnetic field (2,000-3,000 gauss) is used for MRI, then patient comfort is improved, but signal strength and image quality deteriorate
Solution Approach 1:
The patent introduces a SQUID (Superconducting Quantum Interference Device) as an intermediary detection system. The SQUID acts as a highly sensitive mediator that can detect the weak NMR signals at low fields with adequate signal-to-noise ratio, enabling low-field MRI to function effectively
Solution Approach 2:
The patent changes the detection method parameter from conventional RF amplifiers to SQUID-based detection. This parameter change enables the system to achieve adequate signal-to-noise ratio at low magnetic fields, overcoming the signal strength limitation
3Measurement precision
If SQUID-based detection is used at very low fields (1-200 gauss), then signal detection capability is improved, but device complexity and cryogenic requirements worsen
Solution Approach 1:
The patent changes the operating field parameter from very low field (1-200 gauss) to low field (2,000-3,000 gauss or 0.2-0.3 Tesla). This parameter change reduces the signal detection capability slightly but eliminates the need for cryogenic cooling and complex superconducting infrastructure, making the system more practical
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
This approach provides improved T1 contrast and reduced noise, enabling better detection of tissue abnormalities, particularly cancerous tissues, with a more patient-friendly and cost-effective MRI system that is less claustrophobic and requires less stringent magnet homogeneity.
Implementation Method 1
Another approach to detecting the NMR signals for MRI at low fields, developed in recent years but not yet used in practical systems, is to use a Superconducting Quantum Interference Device known as a SQUID
Implementation Method 2
superconducting coils to generate a field of 100 to 300 gauss
Implementation Method 3
the resonant detection circuits to detect the signals with an adequate signal to noise ratio
Implementation Method 4
By applying magnetic field gradients to the subject, the signal frequency becomes dependant on position
Data Source
AI summary
There is described an MRI system in which the detection of the NMR signal is performed by a resonant input at a median field range above 100 gauss and where the main field is cycled to a low field of below 50% of the resonant frequency after the excitation of the NMR signal for a period sufficient to develop differences in magnetisation (T1). The advantage of this system is that images can be generated at much lower field intensities than prior art systems and is able to detect abnormalities in tissue such as cancerous tissues in a patient.