Magnetic Resonance Navigator Signal Correction for Temporal Stability
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Solution Overview
Problem
Temporal stability in series of temporally successive image data sets in magnetic resonance imaging is not consistently ensured due to fluctuations such as baseline drift or jumps in global image intensity, which complicates the detection of local variations during fMRI examinations.
Innovation Solution
A method is introduced to determine and correct for global image intensity fluctuations by acquiring and evaluating a measure that characterizes the global image intensity value, using navigator signals or external signals to compensate for changes, and applying these corrections to the image data sets, either during acquisition or post-acquisition, to ensure temporal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fast imaging sequences are used to acquire image data sets repeatedly in quick time sequence, then productivity is improved, but temporal stability deteriorates due to baseline drift and global image intensity fluctuations
Solution Approach 1:
The patent introduces a navigator signal as an intermediary measurement that specifically monitors global image intensity changes. This navigator signal acts as a mediator between the fast imaging sequence and the correction process, allowing the system to track and compensate for temporal instabilities without slowing down the main image acquisition.
Solution Approach 2:
The patent implements a feedback mechanism where navigator signals are continuously monitored and used to generate correction factors that are applied back to the image data sets. This closed-loop feedback system automatically compensates for temporal drift and intensity fluctuations, maintaining temporal stability while preserving the fast acquisition rate.
2Stability of the object's composition
If correction methods are applied to compensate for temporal fluctuations, then temporal stability is improved, but device complexity increases
Solution Approach 1:
The patent segments the correction process into distinct, modular components: navigator signal acquisition, global intensity measurement, correction factor calculation, and application to image data. This segmentation allows each component to be optimized independently and simplifies the overall implementation by breaking down the complex correction task into manageable steps.
Solution Approach 2:
The correction method is designed to be self-service in that the navigator signals are acquired automatically as part of the imaging sequence, and the correction factors are calculated and applied automatically without requiring manual intervention. The system self-corrects for temporal instabilities, reducing the operational complexity despite the sophisticated correction algorithms.
3Device complexity
If global image intensity changes are not compensated, then device complexity remains low, but measurement precision deteriorates due to inability to detect local variations
Solution Approach 1:
The patent changes the parameter being monitored by introducing navigator signals that specifically measure global image intensity. This parameter change allows the system to detect and correct for intensity fluctuations that would otherwise go unnoticed, thereby improving measurement precision without requiring complex modifications to the imaging sequence itself.
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 method effectively compensates for global image intensity changes, improving the stability of image data sets and enabling more accurate detection of local variations in fMRI imaging by accounting for fluctuations in the image series, thereby enhancing the reliability of metabolically-induced differences and hemodynamically-dependent correlations in neural activity.
Implementation Method 1
The method thereby utilizes the different magnetic properties of oxygenated and deoxygenated blood (what is known as the BOLD effect—BOLD for 'blood oxygen level dependency')
Implementation Method 2
Radio-frequency excitation pulses are radiated into the examination subject to trigger nuclear magnetic resonances, the triggered nuclear magnetic resonances are measured and MR images are reconstructed based thereon
Data Source
AI summary
In a method and magnetic resonance apparatus for acquisition and processing of a series of temporally successive image data sets of the series of temporally successive image data sets is acquired by magnetic resonance technology, wherein k-space image data corresponding to each image data set are acquired, and for each image data set in the series, a determination is made, in at least one first part of that image data set, of a measure that characterizes a global image intensity value of that image data set. At least one second part of the image data sets is corrected using the determined measures and/or the determined measures are used in an evaluation of at least one third part of the image data sets. A temporal change of the global image intensity value in the series of temporally successive image data sets is compensated or taken into account in this manner.