3D MR Acquisition for High-Resolution T1-T2 Mapping
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Solution Overview
Problem
Conventional T1 and T2 mapping techniques in MRI are limited by partial volume effects at the water-fat interface, leading to inaccurate quantification, and they typically acquire only low-resolution 2D slices during breath holds, which restricts the generation of high-resolution whole-heart images.
Innovation Solution
A method using 3D MR acquisition sequences with different parameters to acquire first, second, and third 3D images, determining signal evolutions, and generating T1 and/or T2 maps by comparing these evolutions to a simulation dictionary, enabling the creation of high-resolution, co-registered 3D whole-heart joint T1-T2 maps without breath holds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional 2D slice acquisition during breath holds is used, then the scanning time is reduced and the subject can hold breath, but the resolution is low and partial volume effects occur at water-fat interface
Solution Approach 1:
The patent transitions from 2D slice acquisition to 3D volumetric imaging, enabling high-resolution whole-heart T1 and T2 mapping without breath holds. The 3D acquisition sequences capture the entire heart volume in multiple directions, eliminating partial volume effects at water-fat interfaces while maintaining quantitative accuracy.
Solution Approach 2:
The patent employs multiple 3D MR acquisition sequences with different parameters (inversion time, echo time, flip angle) to acquire images at different time points. By varying these parameters and comparing signal evolutions across sequences, the method achieves accurate T1 and T2 quantification without requiring breath hold maneuvers.
2Measurement precision
If 3D MR acquisition sequences with multiple parameters are used, then high-resolution whole-heart mapping is achieved, but the device complexity and processing requirements increase
Solution Approach 1:
The patent divides the 3D volumetric acquisition into multiple 3D MR sequences with different parameters (first, second, and third sequences). Each sequence acquires a subset of the required data, and the results are combined through signal evolution comparison. This segmentation makes the complex 3D acquisition more manageable and implementable.
Solution Approach 2:
The patent uses a simulation dictionary that contains pre-computed signal evolutions for various T1 and T2 values. Instead of directly solving the complex inverse problem from the acquired images, the method compares actual signal evolutions against the simulated dictionary entries to determine T1 and T2 maps, simplifying the processing of complex multi-parameter data.
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, high-resolution T1 and T2 mapping, reducing partial volume effects and enabling free-breathing sequences, thus improving tissue characterization and disease identification in cardiac imaging.
Implementation Method 1
an inversion pulse is generated and followed by the acquisition of five images. The five images are acquired during the diastolic period of the cardiac cycle within five successive heartbeats
Implementation Method 2
T1 relaxation time constant, also known as the spin-lattice or longitudinal relaxation time, is a measure of how fast the nuclear spin magnetization returns to its equilibrium state after an excitation pulse
Implementation Method 3
acquiring first, second, and third 3D images of the image volume of the subject, wherein each of the first, second, and third 3D images are acquired at a different time using a 3D MR acquisition sequence
Data Source
AI summary
A method and apparatus for generating a T1 or T2 map for a three-dimensional (3D) image volume of a subject. The method includes acquiring first, second, and third 3D images of the image volume of the subject. Signal evolutions of voxels through the first to third 3D images by comparing voxel intensity levels of corresponding voxel locations in the first, second, and third 3D images. A simulation dictionary representing the signal evolutions for a number of different tissue parameter combinations is obtained. The T1 or T2 map is generated by comparing the determined signal evolutions to entries in the dictionary and by finding, for each of the determined signal evolutions, the entry in the dictionary that best matches the determined signal evolution.