Low-Field MRI Inversion Recovery Sequence for Stroke Differentiation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current high-field MRI systems are inconvenient for stroke patients due to the need for electromagnetically shielded rooms and are inaccessible to patients with metal implants, and they struggle to accurately differentiate between hemorrhagic and ischemic strokes within the critical time window for treatment.
Innovation Solution
A low-field MRI stroke identification sequence using an inversion recovery sequence with optimized TR and TI values, minimizing T2 effects, and a device configured to implement this sequence for rapid and accurate hemorrhagic stroke diagnosis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-field MRI (1.5T or 3.0T) is used to improve stroke detection accuracy, then the detection rate of acute cerebral infarction and cerebral hemorrhage is improved, but the device requires installation in specialized electromagnetically shielded rooms which delays treatment time and reduces accessibility
Solution Approach 1:
The patent changes the magnetic field strength parameter from high-field (1.5T or 3.0T) to low-field (0.23T), fundamentally altering the operating conditions of the MRI system. This parameter change enables the device to function without requiring electromagnetically shielded rooms, thereby eliminating the time delay associated with specialized facility requirements while maintaining stroke detection capability
Solution Approach 2:
The patent employs a low-field MRI system that is simpler and more portable compared to high-field systems. This approach uses a less complex, more accessible device that can be deployed quickly without the need for expensive, fixed infrastructure, effectively trading some field strength for rapid deployability and accessibility
2Measurement precision
If high-field MRI is used to improve stroke detection, then the detection rate is improved, but patients with metal implants cannot undergo the scan due to heat generation from electromagnetic wave absorption
Solution Approach 1:
By changing the magnetic field strength parameter to a low value (0.23T), the patent reduces the energy absorption by metal implants to safe levels. This parameter modification allows patients with metal implants or medical assistive devices to safely undergo MRI scanning, significantly expanding patient accessibility while maintaining diagnostic capability
3Speed
If CT is used for rapid stroke diagnosis, then the cerebral hemorrhage detection is highly sensitive and fast, but the detection of acute ischemic stroke is not sensitive with inconspicuous lesion images
Solution Approach 1:
The patent makes the low-field MRI system capable of detecting both cerebral hemorrhage and acute ischemic stroke, unlike CT which is highly sensitive to hemorrhage but insensitive to early ischemic changes. The optimized inversion recovery sequence with specific TR and TI parameters enables this universal detection capability, allowing a single modality to perform multiple diagnostic functions
4Measurement precision
If inversion recovery sequence with optimized TR and TI values is used to differentiate hemorrhagic and ischemic stroke, then the differentiation accuracy is improved, but the sequence parameter optimization requires precise control
Solution Approach 1:
The patent identifies and applies specific parameter values (TR=900-1500ms, TI=685-1000ms) that optimize the contrast between hemorrhagic and ischemic stroke. By determining these optimal parameters through research and fixing them in the protocol, the system achieves high differentiation accuracy while simplifying the control process, as these parameters can be pre-set and automatically applied
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 rapid and accurate differentiation between hemorrhagic and ischemic strokes, improving accessibility for patients and reducing the risk of misdiagnosis, especially in the critical time window for stroke treatment.
Implementation Method 1
a formula of a relative signal intensity of the inversion recovery is expressed as follows: S/PD=T1×(1-exp(-TI/T1))/(1-exp(-TR/T1))×exp(-TE/T2) where S represents a relative signal intensity; PD represents a proton density of tissue; TI represents an inversion recovery time of the inversion recovery sequence; T1 represents a T1 relaxation time of the tissue
Implementation Method 2
The TE is set to a minimum value or a near-minimum value achievable by a system, thereby making exp(-TE×(1/T2last-1/T2)) as close to 1 as possible, and minimizing an influence of an T2 effect on the relative signal intensity S
Implementation Method 3
The disclosure relates to the field of magnetic resonance imaging (MRI) technologies, and particularly to a low field MRI stroke identification sequence
Data Source
AI summary
A low field magnetic resonance imaging (MRI) stroke identification sequence uses an inversion recovery sequence. TE is set to the minimum or near-minimum value achievable by a system to minimize an impact of T2 effect on a signal S. Additionally, it selects combinations of TR values and corresponding TI values to make signal from cerebral hemorrhage appear as high signal, and signals from cerebral infarct tissue and cerebral parenchyma appear as isointense or low signal. This allows for rapid and accurate determination of hemorrhagic stroke and, by utilizing low-field magnetic resonance, enhances the accessibility for patients.