MRI Sequence Controller Magnetization Transfer Pulse Frequency
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Solution Overview
Problem
Conventional magnetic resonance imaging (MRI) techniques struggle to effectively differentiate between restricted protons in macromolecules and free water protons, limiting the ability to accurately assess tissue characteristics and contrast between different tissues, particularly in the brain where grey and white matter differentiation is challenging.
Innovation Solution
The implementation of a magnetic resonance imaging apparatus that applies Magnetization Transfer (MT) pulses with frequencies different from free water protons, acquiring signals across a wide frequency band based on the T2 relaxation time of restricted protons, and utilizing Z-spectra analysis to separate and visualize short and long T2 components, enabling improved tissue contrast and characterization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional MRI techniques are used, then imaging is simple and quick, but the ability to differentiate between restricted protons in macromolecules and free water protons is insufficient
Solution Approach 1:
The patent segments the proton population into two distinct groups: restricted protons in macromolecules and free water protons. By applying MT pulses with specific frequency offsets, the imaging technique selectively targets and differentiates between these two segmented proton populations, enabling precise differentiation of tissue characteristics based on their distinct magnetic resonance properties
Solution Approach 2:
The patent changes the frequency parameter of the applied RF pulses by using MT pulses with frequency offsets different from the Larmor frequency of free water protons. This parameter change allows selective excitation and differentiation of restricted protons versus free water protons, improving measurement precision through frequency-domain separation
2Measurement precision
If MT pulses with frequency offsets are applied to restrict signals of restricted protons, then tissue contrast is improved, but the imaging process becomes more complex and time-consuming
Solution Approach 1:
The patent employs periodic application of MT pulses with specific frequency offsets to repeatedly saturate restricted protons. This periodic action allows the system to accumulate contrast information over multiple pulse cycles while maintaining efficient timing, thereby improving tissue contrast without excessive time penalty
Solution Approach 2:
The patent maintains continuous useful action by applying MT pulses in a sustained manner throughout the imaging sequence, ensuring that the magnetization transfer effect is continuously active. This continuous application maximizes the contrast mechanism's effectiveness while optimizing the balance between contrast quality and acquisition time
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 allows for the detection of macromolecular characteristics in living tissues, providing novel contrast mechanisms and improved differentiation between normal and abnormal tissues, as demonstrated by the successful separation of grey and white matter components in human brains, enhancing diagnostic capabilities.
Implementation Method 1
The MTC effects use magnetic transfer between free water protons and restricted protons. The principle is as follows: first, MT pulses having a resonance frequency different from the resonance frequency of free water protons are applied so as to restrict the signals of restricted protons. The restricted protons are exchanged with the surrounding free-water protons and thus the magnetization of the restricted protons whose signals have been suppressed is transferred to the free water protons, which reduces signals of the free water protons.
Implementation Method 2
CEST is targeting magnetization transfer between restricted protons having a specific frequency (e.g., amine and hydroxyl group protons) and free water protons.
Implementation Method 3
the sequence controller acquires the magnetic resonance signals for each of multiple frequencies while changing the frequency of the MT pulses within a frequency band based on a T2 relaxation time of restricted protons contained in the object to be imaged
Data Source
AI summary
A magnetic resonance imaging apparatus includes a sequence controller. The sequence controller is configured to apply MT (Magnetization Transfer) pulses having a frequency different from a resonance frequency of free water protons and then acquires magnetic resonance signals of an object to be imaged. The sequence controller acquires the magnetic resonance signals for each of multiple frequencies while changing the frequency of MT pulses within a frequency band based on a T2 relaxation time of restricted protons contained in the object to be imaged.