Magnetic Resonance CEST Imaging Frequency Stabilization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Magnetic resonance CEST imaging is sensitive to frequency drift of the main magnetic field, leading to poor performance and excessive fat signal interference in images, which existing post-processing methods cannot adequately correct.
Innovation Solution
A magnetic resonance CEST imaging sequence with a frequency stabilization module that collects non-phase-encoded k-space data at different times to calculate fine and coarse estimates of the main magnetic field frequency drift, adjusting the radio frequency pulse center frequency to correct the drift in real-time and suppress fat signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If data post-processing method is used to correct frequency drift, then frequency correction is achieved, but fat signal suppression is ineffective
Solution Approach 1:
The patent applies preliminary action by performing frequency drift correction at the beginning of the imaging sequence rather than in post-processing. The center frequency of the RF pulse is adjusted based on measured frequency drift before the actual CEST imaging data acquisition, preventing frequency drift from affecting the imaging process in the first place.
Solution Approach 2:
The patent introduces an intermediary measurement process using non-phase-encoded k-space data lines to detect frequency drift. This intermediary measurement enables real-time frequency monitoring and correction, which then serves as a basis for adjusting the main imaging sequence parameters.
2Reliability
If frequency stabilization module is added, then real-time frequency correction and fat signal suppression are achieved, but imaging sequence complexity increases
Solution Approach 1:
The patent segments the imaging sequence into distinct functional modules: a frequency measurement module that acquires non-phase-encoded k-space data, a frequency drift calculation module that computes drift from phase differences, and a frequency correction module that adjusts the center frequency. This segmentation makes the complex sequence more manageable and systematic.
Solution Approach 2:
The patent utilizes parameter changes by measuring frequency drift through phase differences in k-space data and dynamically adjusting the center frequency parameter of the RF pulse. This parameter adjustment is the core mechanism that achieves frequency stabilization without requiring hardware modifications.
3Measurement precision
If three lines of non-phase-encoded k-space data are collected, then frequency drift estimation accuracy is improved, but scanning time increases
Solution Approach 1:
The patent applies partial action by collecting only three specific non-phase-encoded k-space data lines for frequency measurement purposes, rather than acquiring the complete k-space data set. This partial acquisition is sufficient for frequency drift estimation while minimizing the time overhead.
Solution Approach 2:
The frequency measurement using three k-space lines is performed as a preliminary action before the main CEST imaging sequence. By completing the frequency calibration in advance, the patent avoids the need for repeated frequency measurements during the imaging process, thereby reducing total scanning 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 effectively corrects the main magnetic field frequency drift and suppresses fat signals in real-time, improving the quality and reliability of CEST imaging, particularly for tumor detection and classification.
Implementation Method 1
Magnetic resonance CEST (Chemical Exchange Saturation Transfer) imaging is an important molecular magnetic resonance imaging technology
Implementation Method 2
obtaining a fine estimated value of a main magnetic field frequency drift by calculating a phase difference between a first line of non-phase-encoded k-space data and a second line of non-phase encoded k-space data
Data Source
AI summary
A magnetic resonance CEST imaging sequence and device based on a frequency stabilization module are provided. It includes following steps: first, in the frequency stabilization module, exciting a target slice with a small-flip-angle radio frequency pulse, and collecting three lines of non-phase-encoded k-space data; second, obtaining an estimated value of the frequency drift of the main magnetic field by calculating the phase difference between the three lines of non-phase encoded k-space data; third, adjusting a center frequency of the radio frequency pulse based on the calculation result of the frequency drift of the main magnetic field, to realize a real-time correction of the frequency drift of the main magnetic field; and fourth, performing conventional magnetic resonance CEST imaging.