Spin-Echo MRI Susceptibility Mapping for Hemorrhage Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current MRI methods struggle to reliably detect local magnetic susceptibility variations, particularly in brain hemorrhages, due to small phase shifts caused by hemorrhages being masked by the non-homogeneous main magnetic field, making it difficult to differentiate hypo-intense regions accurately.
Innovation Solution
The method involves transmitting two spin-echo pulse sequences with different numbers of refocus pulses and echo times, applying a correction matrix based on calibration images, and generating an image mask to highlight local susceptibility variations, using a permanent magnet MRI device.
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 are masked by the non-homogeneous main magnetic field, making detection difficult
Solution Approach 1:
The patent changes the measurement parameters by acquiring images at multiple different echo times (TE values) and using multiple refocus pulses in the spin-echo sequence. This allows the system to capture different phase evolution states and differentiate between hemorrhage-induced phase shifts and those caused by main field inhomogeneity, thereby improving detection precision and reliability simultaneously
Solution Approach 2:
The patent applies preliminary field mapping and correction by acquiring calibration images and calculating a correction matrix before final hemorrhage detection. This preliminary action compensates for main field inhomogeneity effects, allowing subsequent phase shift measurements to more accurately reflect true hemorrhage locations
2Difficulty of detecting and measuring
If gradient-echo (GRE) sequence with long echo time is used to obtain T2* weighted images, then hemorrhages appear hypo-intense, but other factors such as short T2 relaxation time can also cause hypo-intensity, making accurate declaration difficult
Solution Approach 1:
The patent segments the analysis into multiple independent measurements by acquiring images at different echo times and using different numbers of refocus pulses. This segmentation allows separate evaluation of T2* effects versus susceptibility effects, enabling more precise hemorrhage identification by comparing results across multiple measurement conditions
Solution Approach 2:
The patent introduces an intermediary correction matrix derived from field mapping data. This intermediary element mediates between the raw hypo-intense signals and the final hemorrhage declaration by compensating for confounding factors like main field inhomogeneity and T2 relaxation effects
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 allows for accurate detection of local magnetic susceptibility variations, effectively distinguishing hemorrhages from other hypo-intense regions by emphasizing internal susceptibility gradients, even in non-uniform magnetic fields.
Implementation Method 1
magnetic resonance imaging (MRI) device... transmitting a first spin-echo pulse sequence... transmitting a second spin-echo pulse sequence
Implementation Method 2
first spin-echo pulse sequence includes a first number of refocus pulses and a first echo time (TE) value... second spin-echo pulse sequence includes a second number of refocus pulses and a second TE value
Implementation Method 3
exploits the spin refocusing capability of an adiabatic Carr-Purcell (CP) pulse sequence to measure apparent 1H2O transverse relaxation (T2+) and generate contrast based on microscopic tissue susceptibility
Implementation Method 4
generate contrast based on microscopic tissue susceptibility... Susceptibility contrast was identified
Data Source
Figure 1
Figure 2
Figure 3A~3B
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.