MRI Spin-Echo Imaging for Local Susceptibility Detection
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Solution Overview
Problem
Current MRI methods struggle to reliably detect local magnetic susceptibility variations, such as hemorrhaging in the brain, due to small phase shifts caused by hemorrhages being masked by the non-homogeneous main magnetic field, making it difficult to distinguish from other factors causing hypo-intensity in MRI images.
Innovation Solution
Utilizing a combination of spin-echo pulse sequences with varying numbers of refocus pulses and echo times to generate multiple MRI images, applying correction matrices based on calibration images, and superimposing image masks to highlight local susceptibility variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If susceptibility-weighted imaging (SWI) is used to identify hemorrhaging by detecting local phase changes, then hemorrhage locations can be identified, but the small phase shifts caused by hemorrhages (e.g., 10 degrees) are masked by the non-homogeneous main magnetic field, making detection difficult
Solution Approach 1:
The patent changes the magnetic field parameters by applying multiple spin-echo pulse sequences with different echo times (TE values) and different numbers of refocus pulses. This allows the system to capture phase information at multiple time points, enabling the separation of small hemorrhage-induced phase shifts from the larger background field inhomogeneities through temporal and parametric variation.
Solution Approach 2:
The patent performs preliminary calibration by acquiring calibration images without the sample present to characterize the main magnetic field inhomogeneity. This preliminary measurement allows the system to pre-compute correction factors that are then applied to the actual sample images, effectively removing the harmful background field variations before hemorrhage detection.
2Measurement precision
If multiple spin-echo pulse sequences with different refocus pulses and echo times are used, then local susceptibility variations can be accurately detected, but the imaging process becomes more complex
Solution Approach 1:
The patent segments the imaging process into distinct phases: calibration phase (acquiring reference images without sample), data acquisition phase (acquiring multiple spin-echo sequences with different parameters), and processing phase (applying correction matrices and generating susceptibility maps). This segmentation allows each phase to be optimized independently and simplifies the overall workflow despite the multiple parameters involved.
Solution Approach 2:
The patent introduces correction matrices as an intermediary computational element that mediates between the raw multi-parameter spin-echo data and the final susceptibility measurements. These correction matrices, derived from calibration images, serve as a bridge that automatically handles the complexity of parameter variations while providing accurate susceptibility detection.
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
Accurately identifies regions with varying local magnetic susceptibility by reducing the influence of non-uniform magnetic fields, enhancing the detection of hemorrhages and other susceptibility-related anomalies in brain tissues.
Implementation Method 1
magnetic resonance imaging (MRI) device
Implementation Method 2
spin-echo pulse sequence
Data Source
AI summary
Systems and methods of detecting a portion within tissue that has a variation of local magnetic susceptibility using an MRI device, including: transmitting a first spin-echo pulse sequence to the tissue, wherein the first spin-echo pulse sequence includes a first number of refocus pulses and a first TE value; transmitting a second spin-echo pulse sequence to the tissue, wherein the second spin-echo pulse sequence includes a second number of refocus pulses and a second TE value; obtaining a first image and a second image; determining one or more locations within the second image having a signal intensity that is different than the signal intensity of the same one or more locations within the first image; and identifying a portion of tissue that has a varied local magnetic susceptibility based on the determined one or more locations within the second image.