Contrast Enhanced MRA Fat Suppression via Dixon Technique
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Solution Overview
Problem
Conventional contrast-enhanced magnetic resonance angiography (CE-MRA) techniques require multiple acquisitions, are time-consuming, and struggle with fat signal suppression, especially during first pass imaging, where timing is critical and motion can lead to misalignment issues.
Innovation Solution
A method using a single- or multi-echo data acquisition technique with flexible echo times and a generalized Dixon water-fat separation technique for fat suppression, allowing for fast and reliable CE-MRA imaging without the need for separate baseline scans, enabling accurate timing with the contrast agent's arrival and effective elimination of fat signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional CE-MRA uses repetitive RF pulses for background suppression, then fat signal suppression is achieved, but scan time increases and requires multiple acquisitions
Solution Approach 1:
The patent changes the parameter of echo time (TE) to achieve fat suppression. By acquiring signals at specific echo times where fat and water signals have different phase characteristics, the system can separate and suppress fat signals without requiring multiple acquisitions or repetitive RF pulses, thus reducing scan time while maintaining effective fat suppression
Solution Approach 2:
The patent replaces the mechanical/repetitive approach (repetitive RF pulses) with a signal processing approach (Dixon method). Instead of using multiple repetitive scans to suppress fat, the system uses a single acquisition with specific echo times and processes the signals mathematically to separate fat and water components, achieving the same fat suppression effect with reduced scan time
2Object-affected harmful factors
If conventional CE-MRA uses mask image subtraction, then fat signal elimination is achieved, but motion causes misalignment and reduces reliability
Solution Approach 1:
The patent performs preliminary separation of fat and water signals during the single acquisition process. By using the Dixon method to separately reconstruct fat and water images from the signal data, the system eliminates the need for subsequent subtraction operations, thereby avoiding misalignment issues that arise when subtracting mask images that may have moved between acquisitions
3Object-affected harmful factors
If conventional Dixon method is used for water-fat separation, then fat suppression is achieved, but echo times are too long for first pass imaging
Solution Approach 1:
The patent applies a modified Dixon method that requires fewer and shorter echo times than the conventional approach. Instead of requiring multiple long echo times for complete water-fat separation, the system uses a reduced set of echo times that is still sufficient to achieve effective fat suppression, making it compatible with the fast timing requirements of first pass contrast-enhanced MRA
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 fast and reliable fat suppression in CE-MRA, reducing scan time and improving image quality by allowing flexible echo times, which is crucial for first pass imaging, and is applicable in scenarios with potential motion, such as breath holds or cardiac motion.
Implementation Method 1
The magnetic field produces different energy levels for the individual nuclear spins in dependence on the applied magnetic field strength which spins can be excited (spin resonance) by application of an alternating electromagnetic field (RF field) of defined frequency, the so called Larmor frequency or MR frequency
Implementation Method 2
Any variation of the magnetization can be detected by means of receiving RF antennas, which are arranged and oriented within an examination volume of the MR device in such a manner that the variation of the magnetization is measured in the direction perpendicular to the z-axis
Implementation Method 3
In order to realize spatial resolution in the body, linear magnetic field gradients extending along the three main axes are superposed on the uniform magnetic field, leading to a linear spatial dependency of the spin resonance frequency
Implementation Method 4
processing the datasets using a generalized Dixon water-fat separation technique to eliminate the signal originating from the fat from the background
Data Source
AI summary
The invention relates to a method of performing contrast enhanced first pass magnetic resonance angiography, the method comprising: acquiring (302) magnetic resonance datasets of a region of interest using a single- or multi-echo data acquisition technique, wherein the echo times of the one or multiple echoes are flexible, wherein at the time of the data acquisition the region of interest comprises fat, water and a contrast agent, processing (304) the datasets using a generalized Dixon water-fat separation technique to eliminate the signal originating from the fat from the background for reconstruction of an image data set.