Multi-Nucleus Cardiac MR Imaging with Respiratory Motion Compensation
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Solution Overview
Problem
Clinical cardiac MR spectroscopy is hindered by long examination times and motion artifacts from cardiac and respiratory movements, which reduce spectral resolution and contaminate 1H MR spectra, particularly due to epicardial fat and respiratory motion affecting water suppression and shim optimization.
Innovation Solution
An MR imaging system that adaptively switches between two RF frequencies within a single scan to acquire imaging data sets, using one frequency to track respiratory movement and another to image a spatially localized region, employing 1D/2D PACE navigator gating and volume tracking to correct for respiratory motion, thereby improving spectral resolution and reproducibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a single RF frequency is used for cardiac MR spectroscopy, then the examination time is reduced, but motion artifacts from respiratory movement contaminate the spectrum and reduce spectral resolution
Solution Approach 1:
The patent divides the examination into two separate frequency acquisitions within a single scan: one frequency for respiratory tracking and another for spectroscopy. This segmentation allows simultaneous pursuit of both fast acquisition and motion-free spectroscopy data
Solution Approach 2:
The patent introduces an intermediary respiratory tracking signal acquired at the first RF frequency that serves as a navigator to detect and correct respiratory motion. This intermediary measurement enables the second frequency acquisition to be corrected for motion artifacts
2Measurement precision
If respiratory motion correction is applied, then spectral resolution is improved, but the examination time increases due to additional navigator acquisitions
Solution Approach 1:
The patent merges the respiratory tracking function with the spectroscopy acquisition by using two different RF frequencies within a single scan. The navigator data and spectroscopy data are acquired simultaneously in the same scan time, eliminating the need for separate navigator acquisitions that would extend examination time
Solution Approach 2:
The patent makes the single scan serve multiple functions: acquiring both respiratory tracking information at the first frequency and spectroscopy data at the second frequency. This multi-functionality allows motion correction without extending the examination time
3Adaptability or versatility
If multi-nucleus spectroscopy is performed, then metabolic information is enhanced, but the system complexity increases due to frequency switching requirements
Solution Approach 1:
The patent implements dynamic RF frequency switching during the scan, adapting the transmission frequency based on the nucleus being imaged. The system dynamically transitions between first and second RF frequencies to match the resonant frequencies of different nuclei, enabling versatile multi-nucleus spectroscopy
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 significantly enhances the reliability of cardiac MR spectroscopy by minimizing motion artifacts and optimizing imaging conditions, leading to improved spectral resolution and reproducibility of metabolic imaging of the myocardial triglyceride.
Implementation Method 1
MR spectroscopy (MRS) is used for the non-invasive study of cardiac metabolism... Nuclei of interest for metabolic MRS studies include 1H, 13C, 19F, 23Na, 31P, 39K, 87Rb
Data Source
AI summary
A system for respiratory motion compensated MR imaging or spectroscopy, comprises an MR imaging system. The MR imaging system performs a single imaging scan including, acquiring a first imaging data set representing a spatially localized first imaging region located on a patient diaphragm, using a first RF excitation pulse sequence and by transmitting a nuclei excitation first resonant frequency and receiving data substantially at the first resonant frequency. The MR imaging system derives data representing diaphragm position over a respiratory cycle using the first imaging data set, in the single imaging scan. The MR imaging system in response to determining the diaphragm position is within a predetermined window, acquires a second anatomical imaging data set representing a spatially localized second imaging region using a second RF excitation pulse sequence and by transmitting a nuclei excitation second resonant frequency different to the first resonant frequency and receiving data substantially at the second resonant frequency in the single imaging scan.