MRI Apparatus Velocity Encoding Gradient Pulse Preparation
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Solution Overview
Problem
Magnetic resonance imaging (MRI) techniques face challenges in achieving high-quality images, particularly in areas like the trunk and lower thighs, due to motion artifacts and limited versatility, especially when imaging blood vessels with similar T1 and T2 values and parallel orientations.
Innovation Solution
A magnetic resonance imaging apparatus that executes a preparation sequence involving RF pulses and velocity encoding gradient pulses to differentiate signal intensities based on fluid velocity, allowing for improved image quality by emphasizing moving structures without the need for contrast media.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the FBI method is used to create MRA images by picking up images at multiple timings and using difference values, then image contrast is improved, but body motion artifacts arise significantly and images may be blurred by T2 attenuation
Solution Approach 1:
The patent applies a preparation sequence before the main imaging sequence to pre-magnetize moving fluids (blood) and suppress static tissue signals. This preliminary action enhances the signal from moving blood while suppressing signals from stationary tissues, thereby improving MRA image contrast without requiring multiple timing acquisitions that would be susceptible to body motion artifacts.
2Adaptability or versatility
If conventional imaging methods are used, then imaging can be performed, but the imaging area is restricted resulting in poor versatility
Solution Approach 1:
The patent utilizes velocity encoding gradient pulses that can be adjusted in strength and duration to encode different velocity ranges. By changing the gradient parameters, the imaging system can adapt to different anatomical regions and flow velocities, thereby expanding the imaging area coverage and versatility while maintaining image quality across various conditions.
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
The apparatus enhances image quality and versatility by effectively reducing motion artifacts and improving contrast between moving and static tissues, particularly in areas with challenging anatomy.
Implementation Method 1
a velocity encoding gradient pulse to mutually shift, in the spins flipped by the first RF pulse, the phase of spins of a first velocity and the phase of spin of a second velocity different from the first velocity
Implementation Method 2
a first RF pulse to flip spins oriented in a magnetostatic direction in the subject along a first plane including the magnetostatic direction and a first direction orthogonal to the magnetostatic direction
Implementation Method 3
a killer pulse to generate a gradient magnetic field which extinguishes the transverse magnetization of said spins flipped by said second RF pulse
Data Source
AI summary
Versatility and the quality of images are to be improved. As preparation pulses, a first RF pulse to flip along the yz plane spins oriented in a magnetostatic field direction in a subject; a velocity encoding gradient pulse which, in spins flipped by that first RF pulse, mutually shifts the phase of spins in a static state and the phase of spins in a moving state; and a second RF pulse to flip along the yz plane spins whose phase has been shifted by the velocity encoding gradient pulse are successively transmitted. After that, a killer pulse is transmitted to extinguish the transverse magnetizations of the spins flipped by the second RF pulse.