K-space line acquisition timing for MRI noise reduction
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Solution Overview
Problem
Magnetic resonance systems experience loud vibrations and noise due to rapid changes in magnetic field gradients during MR data acquisition, causing discomfort and anxiety for patients.
Innovation Solution
A method for acquiring MR data by defining shorter time periods for k-space lines in the central region of k-space, reducing the time for switching gradients and thus minimizing loudness, while maintaining image contrast by extending acquisition time for k-space lines outside the central region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the slew rate of magnetic field gradients is increased to improve data acquisition speed, then productivity is improved, but audible noise increases
Solution Approach 1:
The patent divides k-space into multiple regions (central region and outer regions) and applies different acquisition strategies to each region. Central k-space lines are acquired with shorter time periods and higher slew rates, while outer k-space lines are acquired with longer time periods and lower slew rates, segmenting the noise-generating process to minimize overall audible noise while maintaining productivity
Solution Approach 2:
Different quality parameters (time period duration and slew rate) are applied locally to different regions of k-space. The central region receives optimized short time periods for efficiency, while outer regions receive extended time periods for noise reduction, creating local quality variations that resolve the contradiction between speed and noise
2Object-affected harmful factors
If the time period for k-space line acquisition is shortened to reduce loudness, then audible noise is reduced, but measurement precision may be affected
Solution Approach 1:
The patent segments k-space acquisition into different temporal strategies: central lines use short time periods to minimize loudness, while outer lines use longer time periods to preserve measurement precision. This segmentation ensures that the region most critical for contrast (central k-space) is acquired during the quietest phase, while less critical regions can tolerate longer acquisition
Solution Approach 2:
The patent converts the harmful effect of loud noise into a beneficial temporal structure: by accepting that central k-space lines will be acquired during shorter, louder intervals, the overall measurement precision is preserved because the most contrast-critical data is captured efficiently, while outer lines are acquired during quieter, longer intervals that minimize noise impact
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
Significantly reduces the loudness of the magnetic resonance system during data acquisition, with less than 6% of the acquisition time being 'loud', allowing for a quieter measurement process without compromising image quality.
Implementation Method 1
Because the gradient coils by means of which the magnetic field gradients are generated are located within the main magnetic field (B0 field) of the magnetic resonance scanner, this causes a Lorentz force to be generated, which leads to a mechanical excitation of the gradient system
Implementation Method 2
If there is a rapid change in the magnetic field gradients, and hence a rapid change in the Lorentz forces, this results in strong vibrations of the entire structure of the magnetic resonance scanner. These vibrations can also be transmitted via the ambient air
Data Source
AI summary
For each k-space line, a time period is defined that starts with the application of the RF pulse directly prior to the acquisition of the respective k-space line, and ends at the time point of the echo during the acquisition of the MR data of the respective k-space line. This time period is set shorter for those k-space lines that lie in a central region of k-space than for k-space lines that lie outside of the central region.