Unipolar Slab Selection Gradient Pulse for 3D MRI Artifact Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current 3DUTE MRI techniques face challenges in achieving ultrashort echo times while minimizing image artifacts, particularly for musculoskeletal tissues, due to excessive scan durations and artifacts caused by slab selection methods.
Innovation Solution
The method involves applying a unipolar slab selection gradient pulse concurrent with an excitation signal and a minimal-duration rewinder pulse of less than 30 μs immediately after, under the polarizing field, to reduce echo times and minimize artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If conventional slab selection methods are used in 3DUTE MRI, then image coverage is achieved, but echo time increases and image artifacts occur
Solution Approach 1:
The patent changes the polarity parameter of the slab selection gradient pulse from bipolar to unipolar, and adjusts the duration parameter of the rewinder pulse to less than 30 μs. These parameter changes enable achievement of ultrashort echo times (less than 100 μs) while minimizing image artifacts by eliminating the need for long rewinder gradients.
2Object-affected harmful factors
If longer scan durations are used to reduce artifacts, then image quality improves, but productivity decreases
Solution Approach 1:
The patent applies a minimal-duration rewinder pulse (less than 30 μs) that quickly rephases the spins without requiring long scan durations. This allows the system to rush through the necessary gradient rephasing in a very short time, achieving both artifact reduction and high productivity with ultrashort echo times.
3Loss of time
If unipolar slab selection gradient pulse is applied concurrent with excitation signal, then echo time is reduced, but gradient pulse timing precision must be increased
Solution Approach 1:
The patent merges the slab selection gradient pulse with the excitation signal timing, applying them concurrently. This integration simplifies the timing control requirements while achieving ultrashort echo times, as the gradient pulse does not need to be applied separately after the excitation but rather in conjunction with it.
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 significant reduction of echo times to less than 30 μs, achieving high-quality images with reduced artifacts, improving data collection efficiency and image clarity for musculoskeletal tissues.
Implementation Method 1
When a substance such as human tissue is subjected to a uniform magnetic field (a polarizing field B0), the individual magnetic moments of particle spins in the tissue attempt to align with this polarizing field, but precess about it in random order at their characteristic Larmor frequency.
Implementation Method 2
If the substance, or tissue, is subjected to an RF magnetic field (excitation field B1), which defines an x-y plane and varies at a frequency near a Larmor frequency corresponding to spins of selected particles, the net aligned moment, or 'longitudinal magnetization' (M2) of those selected particles, may be rotated, or 'tipped ', into the x-y plane to produce a net transverse magnetic moment M.
Implementation Method 3
After the excitation signal B1 is terminated, the tipped spins 'relax' back into the precession defined by the polarizing field, and by doing so, produce RF signals.
Implementation Method 4
In order to form a pixelated image that a human doctor can interpret, gradient magnetic fields (Gx, Gy, Gz) are applied to localize the tissue response to the excitation signal B1.
Data Source
AI summary
A method for slab selection in ultrashort echo time three-dimensional MRI includes applying an excitation signal to a target under a polarizing field; applying a unipolar slab selection gradient pulse to the target, concurrent with the excitation signal; and applying a rewinder pulse to the target for less than about 30 μs, immediately after the slab selection gradient pulse, and still under the polarizing field.