UTE MRI Radial Projection Interleaving for Short T2 Imaging
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Solution Overview
Problem
Magnetic resonance imaging (MRI) techniques face challenges in generating high-resolution images of materials with short transverse relaxation times (T2), such as cortical bone, due to streak artifacts and low signal intensity from fast-relaxing tissues, which limits contrast and spatial resolution.
Innovation Solution
The implementation of ultrashort echo time (UTE) MRI techniques using radial ramp sampling, variable-rate selective excitation, and fast transmit/receive switching, combined with interleaved projection reconstruction and long adiabatic pulses for signal suppression, allows for the acquisition and processing of signals from tissues with short T2 values, reducing streak artifacts and enhancing image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional MRI techniques are used to image short T2 tissues, then standard imaging protocols can be applied, but streak artifacts increase and signal intensity decreases
Solution Approach 1:
The patent implements dynamic adjustment of echo times across multiple groups of radial projections. Different echo times are assigned to different groups, allowing the system to adapt to the fast decay characteristics of short T2 tissues while maintaining adequate signal intensity for image reconstruction, thereby reducing streak artifacts caused by signal loss.
Solution Approach 2:
The acquisition of radial projections is segmented into multiple groups, with each group acquired at a different echo time. This segmentation allows selective optimization for different tissue relaxation characteristics and enables interleaved reconstruction that reduces streak artifacts by distributing artifacts across multiple frequency components.
2Manufacturing precision
If conventional MRI techniques are used for short T2 tissues, then standard acquisition sequences can be employed, but spatial resolution and contrast are limited
Solution Approach 1:
The system dynamically varies echo times across different groups of radial projections to match the fast relaxation characteristics of short T2 tissues. This dynamic approach captures signal before complete decay occurs, maintaining adequate signal intensity while achieving high spatial resolution through the radial sampling scheme.
Solution Approach 2:
The patent changes the echo time parameter across different groups of radial projections. By adjusting this critical timing parameter, the system optimizes signal capture for fast-relaxing tissues, enabling both high spatial resolution and sufficient contrast for short T2 tissue imaging.
3Reliability
If radial projections are acquired at multiple echo times, then short T2 tissue signal can be captured, but data processing complexity increases
Solution Approach 1:
The patent employs interleaved image reconstruction that creates multiple image copies from different groups of radial projections acquired at different echo times. This copying approach allows straightforward reconstruction algorithms to be applied to each group separately, simplifying the overall processing while maintaining signal capture from short T2 tissues.
4Object-affected harmful factors
If interleaved groups of radial projections are used, then streak artifacts are reduced, but acquisition time may increase
Solution Approach 1:
The patent maintains continuous data acquisition by interleaving multiple groups of radial projections across different echo times within a single scan. This continuous sampling approach efficiently captures the decaying signal from short T2 tissues without requiring multiple separate scans, thereby reducing streak artifacts while maintaining clinically acceptable scan times.
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
UTE MRI effectively generates high spatial and spectral resolution images of short T2 tissues with reduced streak artifacts, improving contrast and dynamic range, particularly for tissues like cortical bone, deep cartilage, and tendons, while maintaining clinical scan times.
Implementation Method 1
radio frequency (rf) pulses are applied to a sample to produce magnetic resonance (MR) echo signals from the sample at multiple different echo times
Implementation Method 2
Magnetic field gradients are applied to the sample to select for acquisition components of each of the MR echo signals
Data Source
AI summary
Radio frequency (rf) pulses are applied to a sample to produce magnetic resonance (MR) echo signals from the sample at multiple different echo times. Magnetic field gradients are applied to the sample to select for acquisition components of each MR echo signal. The selected components correspond to groups of radial projections in k-space. Each group is associated with one of the echo times. Each group defines a different set of projection angles in the k-space, and the groups are interleaved to reduce streak artifacts in spectroscopic images associated with a resonance frequency. Images of the sample are generated based on acquired MR signals. In some implementations, an echo time of eight microseconds or less is included in the multiple different echo times.