RF Encoding MRF Slice Resolution
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Solution Overview
Problem
Conventional magnetic resonance fingerprinting (MRF) techniques face limitations in achieving high-resolution imaging due to restricted slice resolution in 2D MRF and excessive scanning time, data volume, and computational requirements in 3D MRF methods.
Innovation Solution
A high-resolution MRF method based on radio frequency encoding is introduced, which involves designing and generating multiple magnetic resonance fingerprinting sequences with different radio frequency pulses, scanning, reconstructing k-space data, and matching time evolution signals with a dictionary to obtain quantitative tissue parameter images with increased resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional 2D MRF is used, then scanning time and computational resources are reduced, but slice resolution is limited to 3-5 mm
Solution Approach 1:
The patent divides the excitation profile into n continuous sub-slices, each with thickness of 1/n of the full thickness. By applying phase modulation to different sub-slices using n different radio frequency pulses, the method achieves high-resolution imaging (n times improvement) while maintaining the efficiency of 2D MRF scanning. This segmentation of the excitation profile into manageable sub-slices allows parallel acquisition of multiple slices without proportionally increasing scanning time.
2Measurement precision
If 3D MRF with non-Cartesian trajectory is used, then slice resolution is improved to about 1 mm, but scanning time and computing resources increase significantly
Solution Approach 1:
The patent extracts the slice selection function from a full 3D acquisition and implements it through phase-modulated radio frequency pulses in a 2D MRF framework. By taking out the slice differentiation function and implementing it through frequency-domain encoding rather than spatial 3D sampling, the method achieves high resolution without the computational burden of 3D non-Cartesian trajectory reconstruction.
Solution Approach 2:
The patent replaces the mechanical 3D spatial sampling approach with a frequency-domain encoding approach using radio frequency pulse modulation. Instead of acquiring data through complex 3D non-Cartesian trajectories requiring heavy computational reconstruction, the method uses phase-modulated RF pulses to encode slice information directly in the signal domain, substituting computational complexity with simpler signal processing.
3Measurement precision
If 3D MRF with non-Cartesian trajectory is used, then slice resolution is improved to about 1 mm, but data volume becomes too large for practical application
Solution Approach 1:
The patent segments the excitation profile into n sub-slices and acquires data for each sub-slice independently through phase-modulated RF pulses. This segmentation approach reduces the data volume compared to full 3D acquisition, as each sub-slice acquisition is similar to a standard 2D MRF scan, while still achieving high-resolution imaging through the combined information from all sub-slices.
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
The method achieves a slice resolution increased by n times without reducing the signal-to-noise ratio, as demonstrated by phantom and in vivo brain experiments, providing higher-resolution quantitative imaging results suitable for scientific research and clinical applications.
Implementation Method 1
a corresponding excitation profile of each radio frequency pulse respectively applies a phase modulation of magnitude π to a different sub-slice
Implementation Method 2
establishing a dictionary reflecting a signal timing change based on a Bloch equation
Data Source
AI summary
The present invention is a high-resolution magnetic resonance fingerprinting method based on radio frequency encoding, a device and storage medium, where radio frequency encoding is introduced into MRF, n time evolution signals can be collected by designing and respectively scanning a set of n radio frequency pulse signals, separate time evolution signals representing n sub-slices can be obtained after decoding and calculating according to a encoding process, and then separate quantitative images of the n sub-slices can be obtained through dictionary matching. Compared with conventional MRF, a slice resolution of the quantitative images obtained in the imaging method of the present invention is increased by n times and a signal-to-noise ratio is not reduced. Through a phantom experiment and a human experiment, accuracy of quantitative effect and an effective improvement of the resolution of the present invention are proved, and the present invention can provide higher-resolution quantitative imaging results.