MR Sequence Segment Correlation for Motion Artifact Control
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Solution Overview
Problem
Magnetic resonance imaging is hindered by motion artifacts due to patient movements during prolonged acquisition times, particularly in TSE and GRE sequences, which conventional reconstruction methods struggle to address effectively, especially when combined with deep-learning reconstructions.
Innovation Solution
A method that utilizes navigator submodules to acquire and correlate navigator data across sequence segments, discarding or weighting motion-affected data to improve image quality by reducing artifacts, compatible with trained reconstruction functions like unrolled neural networks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If TSE sequences with multiple echo trains are used to improve image quality, then manufacturing precision is improved, but loss of time increases due to prolonged acquisition duration
Solution Approach 1:
The patent applies preliminary action by acquiring navigator data at the beginning of each sequence segment before the actual imaging data acquisition. This preliminary navigator data is then used to predict and correct for motion artifacts that will occur during the subsequent imaging process, allowing for motion compensation without extending the main imaging acquisition time.
2Object-affected harmful factors
If conventional reconstruction methods are used to reduce motion artifacts, then object-affected harmful factors are reduced, but manufacturing precision deteriorates because artifacts are lost in noise
Solution Approach 1:
The patent implements feedback by using acquired navigator data to continuously monitor patient motion and dynamically adjusting the imaging process. The navigator data provides real-time feedback about patient position and motion, which is then used to correct k-space data and compensate for motion artifacts, maintaining image quality while reducing artifacts.
3Loss of time
If trained reconstruction algorithms are used to shorten acquisition time, then loss of time is reduced, but object-affected harmful factors worsen because motion artifacts are reconstructed more visibly
Solution Approach 1:
The patent introduces navigator data as an intermediary element that mediates between the imaging process and motion correction. The navigator data serves as a separate monitoring channel that tracks patient motion independently, allowing trained reconstruction algorithms to process imaging data quickly while using navigator information to identify and correct motion-related artifacts in the reconstruction process.
4Object-affected harmful factors
If navigator data is acquired in each sequence segment to detect motion, then object-affected harmful factors are reduced, but device complexity increases due to additional submodules and processing
Solution Approach 1:
The patent applies merging by combining the navigator data acquisition with the existing sequence segment structure. Instead of adding completely separate navigation sequences, the navigator data is integrated into the same sequence segments that acquire imaging data, using the same radiofrequency pulses and readout mechanisms. This consolidation reduces overall system complexity while maintaining motion detection capabilities.
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
Enhances image quality by significantly reducing motion artifacts while maintaining high-quality reconstructions, even with undersampled data, and is compatible with deep-learning techniques, unlike existing motion correction approaches.
Implementation Method 1
Magnetic resonance imaging is now a frequently used diagnostic and monitoring tool in medical applications
Implementation Method 2
a gradient coil arrangement (23) and a control apparatus (25)
Implementation Method 3
a radiofrequency coil arrangement (24) for receiving magnetic resonance data
Data Source
AI summary
Method for operating an MR apparatus in an acquisition process in accordance with an acquisition protocol including, in at least one repetition, sequence segments of an MR sequence, wherein each sequence segment includes a preparation module and a readout module, and each readout module includes readout submodules, each readout submodule including respective RF pulses followed by respective readout time periods during which MR data is acquired. The method includes: acquiring navigator dataset of the sequence segment for each readout module using a navigator submodule included in the readout module; determining correlation information for each sequence segment by comparing the navigator dataset of the sequence segment with a navigator dataset of a further sequence segment; and evaluating the correlation information to select sequence segments whose MR data is discarded, and/or to assign a weighting to the MR data of some of the sequence segments prior to reconstruction of an MR image.