IG Fitting Technique for T1 Mapping Accuracy
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Solution Overview
Problem
Conventional cardiac MRI techniques, such as Modified Look-Locker Inversion Recovery (MOLLI), require rest periods for full magnetization recovery, leading to inefficiencies and potential errors due to incomplete recovery, especially in patients with faster heart rates or arrhythmias, and result in longer scan times and reduced precision.
Innovation Solution
The IG fitting technique allows for the generation of accurate T1 maps using any combination of inversion groupings and rest periods, including no rest period, by modeling the signal behavior of each inversion grouping independently and combining T1 estimates from individual groupings, thereby reducing scan time and increasing flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If rest periods are used for full magnetization recovery between inversion groupings, then T1 mapping accuracy is improved, but scan time increases and efficiency decreases
Solution Approach 1:
The patent segments the T1 mapping process into multiple inversion groupings, where each grouping is independently fitted to calculate T1 values. This allows data from different groupings to be processed separately without requiring full magnetization recovery between them, thereby eliminating the need for rest periods and reducing scan time while maintaining accuracy.
Solution Approach 2:
The patent changes the fitting approach by introducing grouping-specific parameters (such as offset terms) that account for incomplete magnetization recovery between groupings. This parameter modification allows accurate T1 calculation even when magnetization does not fully recover, resolving the contradiction between accuracy and scan time.
2Measurement precision
If rest periods are used for full magnetization recovery, then precision of T1 fit is improved, but scan efficiency decreases
Solution Approach 1:
By dividing the data into separate inversion groupings and fitting each independently, the patent eliminates the need for rest periods that would otherwise be required to ensure complete magnetization recovery. This segmentation maintains fitting precision while significantly improving scan efficiency.
Solution Approach 2:
The patent accepts that magnetization may not fully recover between inversion groupings (partial action), and compensates through modified fitting algorithms that account for this incomplete recovery. This approach maintains precision without requiring the excessive action of full recovery periods.
3Measurement precision
If conventional MOLLI technique is used with rest periods, then T1 map accuracy is maintained, but flexibility for different heart rates is reduced
Solution Approach 1:
The patent introduces dynamic, grouping-specific parameters in the fitting model that adapt to the actual magnetization state at each inversion grouping. This dynamic approach allows the technique to accommodate varying heart rates and arrhythmias without requiring fixed rest periods, thereby improving flexibility while maintaining accuracy.
Solution Approach 2:
By modifying the fitting parameters to include grouping-specific offsets and by allowing different fitting models for different groupings, the patent creates a versatile system that can accurately handle various heart rates and rhythm conditions without being constrained by fixed rest period requirements.
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 precise T1 mapping with reduced sensitivity to heart rate variability and arrhythmias, allowing for shorter scan times and improved accuracy, while maintaining T1 map accuracy and robustness across different heart rates.
Implementation Method 1
The rate at which the magnetization recovers is referred to as its 'T1 value'. T1 is a characteristic property of tissue.
Data Source
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AI summary
Methods and systems for performing T1 mapping. T1 samples are obtained from an acquisition including one or more inversion groupings. The acquisition may be designed to result in incomplete tissue magnetization recovery between inversion groupings. The acquisition may be designed for the use of non-uniform, non-180° preparatory pulses. The method may also include the combined use of data from different inversion groupings. A model is used in which fit parameters are variable dependent on the inversion grouping.