Motion-Stable Slice Multiplexing in MRI
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Solution Overview
Problem
Current slice multiplexing methods in magnetic resonance imaging (MRI) face challenges in efficiently separating measurement data from multiple slices, especially under physiological motion, leading to artifacts and increased acquisition time due to the need for additional reference data and differing measurement parameters.
Innovation Solution
A method that acquires reference data and measurement data simultaneously using undersampled three-dimensional sampling patterns, ensuring complete k-space sampling in a central region, allowing for effective separation of measurement data from multiple slices while minimizing the influence of physiological motion and reducing the need for additional reference data acquisition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If slice multiplexing methods are used to acquire data from multiple slices simultaneously, then acquisition time is reduced, but separation of measurement data becomes unstable under physiological motion causing artifacts
Solution Approach 1:
The patent applies preliminary action by acquiring reference data at the beginning of the measurement process, before physiological motion occurs. This reference data is then used for separation throughout the measurement, establishing a stable baseline that compensates for subsequent motion artifacts.
Solution Approach 2:
The patent changes the sampling pattern parameter dynamically - using different undersampling patterns for reference data acquisition versus measurement data acquisition. This parameter change allows the system to optimize for both stable separation (reference) and efficient acquisition (measurement) simultaneously.
2Measurement precision
If additional reference data is acquired separately for each slice, then data separation accuracy is improved, but acquisition time and SAR load increase
Solution Approach 1:
The patent merges the acquisition of reference data and measurement data into a single simultaneous process. By acquiring reference data for multiple slices at the same time as measurement data, the system eliminates separate reference acquisition steps, reducing total acquisition time while maintaining separation accuracy.
Solution Approach 2:
The patent makes the reference data acquisition multi-functional by simultaneously serving as reference data for multiple slices. A single reference data acquisition process provides calibration information for separating measurement data from multiple slices, eliminating the need for separate reference acquisitions for each slice.
3Manufacturing precision
If reference data and measurement data are acquired at different times, then complete k-space sampling is achieved, but physiological motion causes artifacts during separation
Solution Approach 1:
The patent ensures continuity of useful action by acquiring both reference data and measurement data continuously during the same physiological state. This simultaneous acquisition eliminates temporal gaps that would otherwise allow physiological motion to occur between reference and measurement acquisitions, preventing motion artifacts.
Solution Approach 2:
The patent performs preliminary acquisition of reference data within the same physiological state as the measurement data. By establishing the reference baseline during the actual measurement conditions rather than beforehand, the system ensures that both datasets are affected equally by physiological motion, enabling accurate separation.
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 stabilizes the separation of measurement data under physiological motion, reduces artifacts, and decreases the overall acquisition time and specific absorption rate (SAR) load, while maintaining high image quality by ensuring both reference and measurement data are acquired during the same physiological state.
Implementation Method 1
Radio-frequency excitation pulses (RF pulses) are applied to the object under examination in order to induce nuclear spin resonances, the induced nuclear spin resonances are measured as so-called k-space data
Implementation Method 2
For spatial coding of the measurement data, the basic magnetic field is superimposed with rapidly switched magnetic gradient fields
Data Source
AI summary
Reference data is acquired by a slice multiplexing technique on the basis of which calibration data is determined and used to separate measurement data that has been acquired in collapsed form also by a slice multiplexing technique from at least two slices and still has to be separated into single-slice measurement data. As a result, both the reference data and the measurement data to be separated are acquired from several slices simultaneously in each case and hence during the same physiological state of motion in each case. This reduces the sensitivity to motion of a separation of the measurement data performed on the basis of the reference data.