MRI Z-Spectrum Decomposition for Physiological Change Detection
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Solution Overview
Problem
Current Magnetic Resonance Imaging (MRI) methods using the Chemical Exchange Saturation Transfer (CEST) method focus primarily on signal components within a narrow frequency range of ±1,000 Hz, neglecting broader signal components, and are not sensitive to small changes in physiological states such as exercise, head movement, or drug administration.
Innovation Solution
A magnetic resonance imaging apparatus that executes a first pulse sequence followed by a second pulse sequence after a physiological state change, generating and analyzing Z-spectra to decompose them into Lorentzian spectra, allowing for the detection of changes in cerebral environments and other organs due to physiological changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the CEST method focuses on signal components within a narrow frequency range of ±1,000 Hz, then the imaging specificity for certain proton exchanges is improved, but the detection sensitivity to small physiological changes deteriorates
Solution Approach 1:
The patent segments the Z-spectrum analysis into multiple Lorentzian components, each representing different proton exchange processes. By decomposing the broad frequency spectrum into distinct segments, the method can analyze both narrow-specific and broad-sensitivity signal components separately, resolving the contradiction between imaging specificity and detection sensitivity
Solution Approach 2:
The patent extends the analysis from a one-dimensional frequency spectrum to a two-dimensional analysis by fitting multiple Lorentzian components with different parameters (amplitude, width, center frequency). This dimensional expansion allows simultaneous extraction of both specific narrowband information and broad sensitivity characteristics
2Device complexity
If the CEST method uses a narrow frequency range of ±1,000 Hz, then the processing complexity is reduced, but the information coverage of signal components deteriorates
Solution Approach 1:
The patent segments the broad frequency spectrum into multiple analyzable Lorentzian components. Each component represents a specific proton exchange process with characteristic parameters, allowing comprehensive information coverage while maintaining manageable processing complexity through structured decomposition
Solution Approach 2:
The patent changes the analysis parameters by fitting multiple Lorentzian functions with varying amplitudes, widths, and center frequencies to different regions of the Z-spectrum. This parameter variation enables comprehensive coverage of signal components across the full frequency range while organizing the complex data into interpretable physical parameters
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
Enables the rendering of small impacts on cerebral environments and other organs caused by changes in physiological states, such as exercise or drug administration, which were previously undetectable, and can be applied to various organs like the brain, myocardium, kidney, or liver.
Implementation Method 1
sequence controlling circuitry configured to execute a first pulse sequence including application of a Magnetization Transfer (MT) pulse
Implementation Method 2
a so-called Chemical Exchange Saturation Transfer (CEST) method is known by which specific exchangeable protons are selectively saturated
Implementation Method 3
Magnetic resonance imaging apparatus that executes a first pulse sequence including application of a Magnetization Transfer (MT) pulse
Data Source
AI summary
A magnetic resonance imaging apparatus according to an embodiment includes sequence controlling circuitry and processing circuitry. The sequence controlling circuitry is configured to execute a first pulse sequence including application of a Magnetization Transfer (MT) pulse and to subsequently execute a second pulse sequence including application of an MT pulse after an action that causes a change in a physiological state of a patient. The processing circuitry is configured to generate a first Z-spectrum based on data obtained by executing the first pulse sequence, to generate a second Z-spectrum based on data obtained by executing the second pulse sequence, and to generate data by performing an analysis based on the first Z-spectrum and the second Z-spectrum.