T2 Relaxation Quantification via Bloch Simulation Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for quantifying T2 relaxation times are challenging due to long scan times, contamination from stimulated echoes, and sensitivity to magnetic field inhomogeneities and diffusion weighting, leading to inaccurate T2 value calculations in fast multi-spin echo sequences.
Innovation Solution
The use of Bloch simulations to model coherence pathways and experimental factors in MRI, allowing for time-efficient one-dimensional computer simulations to correct distorted data and generate accurate T2-maps, incorporating RF pulse shapes, spin diffusion, and magnetic field non-uniformities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fast multi spin-echo sequences are used to reduce scan time, then productivity is improved, but measurement precision deteriorates due to contamination from stimulated echoes and indirect echoes
Solution Approach 1:
The patent applies preliminary action by performing Bloch simulations before actual data acquisition to predict and characterize the distortion patterns caused by stimulated echoes. These simulations generate expected distortion curves that are then used to correct the actual measured data, effectively preparing correction factors in advance to eliminate the harmful effects of echo contamination.
Solution Approach 2:
The patent introduces an intermediary element - a distortion correction factor derived from Bloch simulations - that mediates between the raw distorted echo data and the final T2 quantification. This intermediary correction factor acts as a bridge that transforms the contaminated fast multi-echo data into accurate T2 values without requiring full single-echo acquisition times.
2Ease of operation
If conventional exponential decay fitting is applied to fast multi spin-echo data, then ease of operation is improved, but measurement precision deteriorates due to distortion from recurring echoes
Solution Approach 1:
The patent introduces a distortion correction factor as an intermediary that modifies the standard exponential decay model. Instead of directly fitting distorted data to a simple exponential, the method fits the data to an exponential multiplied by a correction factor derived from Bloch simulations, thereby maintaining ease of operation while improving accuracy.
Solution Approach 2:
The patent modifies the fitting model by introducing an additional parameter - the distortion correction factor - that accounts for stimulated echo effects. This parameter change transforms the simple exponential decay model into a more accurate model that captures the complex distortion patterns while still being computationally tractable.
3Measurement precision
If full single-echo spin-echo acquisitions are used to achieve accurate T2 quantification, then measurement precision is improved, but productivity deteriorates due to long scan times of dozens of minutes
Solution Approach 1:
The patent uses Bloch simulations to create a computational copy or model of the expected echo train distortion patterns. Instead of acquiring full single-echo data for each measurement point, the method uses these simulated distortion curves as references to correct faster multi-echo acquisitions, effectively copying the correction information from simulations to actual measurements.
Solution Approach 2:
The patent performs preliminary Bloch simulations to characterize distortion patterns before actual data acquisition. These simulations pre-compute the expected distortion curves that are then used to correct the faster multi-echo measurements, eliminating the need to perform time-consuming full single-echo acquisitions for each measurement.
4Measurement precision
If analytical or numerical stepwise tracing of coherence pathways is used to correct artifacts, then measurement precision may be improved, but device complexity increases due to high numerical complexity
Solution Approach 1:
The patent extracts only the essential distortion characteristics from full Bloch simulations by generating pre-computed distortion correction curves. Instead of performing complete numerical tracing of all coherence pathways during data analysis, the method extracts the key distortion patterns into lookup tables or reference curves that can be applied more simply to correct actual measurements.
Solution Approach 2:
The patent performs the complex numerical tracing of coherence pathways in advance during simulation stages, storing the results as distortion correction factors. This preliminary computation eliminates the need to perform equally complex numerical tracing during actual data analysis, reducing device complexity while maintaining correction accuracy.
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 enables accurate T2 mapping in clinically feasible scan times with reduced error rates, improving the precision of T2 relaxation time quantification and reducing the impact of artifacts, thus enhancing diagnostic capabilities.
Implementation Method 1
fast multi spin-echo nuclear magnetic resonance ('NMR') sequences
Implementation Method 2
full single-echo spin-echo ('SE') acquisitions
Implementation Method 3
contamination of a train of echoes by stimulated and indirect echoes
Implementation Method 4
Bloch simulations of the experimental pulse sequence
Implementation Method 5
single excitation radiofrequency pulse
Data Source
AI summary
A method and a device are provided that improve quantification of the spin-spin relaxation (“T2”) time of an image in nuclear magnetic resonance (“NMR”) applications using fast multi spin-echo sequences. The method employs time-efficient computer simulations for exact modeling of spurious stimulated echoes in multi-dimensional magnetic resonance imaging (“MRI”) runs. The method employs Bloch simulations and can use a plurality of parameters to produce echo modulation curves prior to correcting distorted experimental data based on pre-calculated simulation values.