3D MRI Vessel Wall Imaging Motion Robustness
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Solution Overview
Problem
Current 3D MRI techniques for carotid vessel wall imaging face challenges with motion artifacts due to arterial pulsation, breathing, and involuntary patient movement, leading to poor image quality and long imaging times, while radial k-space sampling struggles to maintain effective magnetization preparation for blood and fat signal nulling.
Innovation Solution
A 3D MRI system combining magnetization preparation sequences for blood and fat signal suppression with a stack-of-stars k-space sampling technique, which oversamples data near the Kz axis to reduce motion artifacts, using a sequence of dark-blood and fat-saturation pulses followed by data readouts, and sampling k-space lines in radial directions in a Cartesian order to maintain effective signal nulling and fat saturation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If 3D MRI techniques are used for carotid vessel wall imaging, then volumetric spatial coverage and imaging efficiency are improved, but motion artifacts increase due to long imaging times
Solution Approach 1:
The patent applies magnetization preparation sequences (dark-blood preparation and fat saturation) before the actual imaging readout to pre-suppress unwanted signals. This preliminary action ensures that blood and fat signals are nulled before data acquisition begins, maintaining signal suppression effectiveness throughout the 3D imaging process despite motion artifacts
Solution Approach 2:
The patent employs a stack-of-stars radial k-space sampling trajectory that dynamically adapts to motion by continuously oversampling the center of k-space. This dynamic sampling approach allows the imaging system to maintain robustness against motion artifacts while achieving complete volumetric coverage, resolving the contradiction between imaging efficiency and image quality
2Reliability
If radial k-space sampling is used to reduce motion artifacts, then motion robustness is improved, but magnetization preparation effectiveness deteriorates
Solution Approach 1:
The patent applies different sampling densities to different regions of k-space, with oversampling concentrated at the center (origin) and progressively less sampling toward the periphery. This local quality approach ensures that the most critical region for motion robustness receives enhanced sampling while maintaining overall imaging efficiency and preserving magnetization preparation effectiveness
Solution Approach 2:
The patent extends the radial sampling approach from 2D to 3D k-space using a stack-of-stars trajectory. This dimensional extension allows the method to maintain motion robustness in three-dimensional volumetric imaging while preserving the benefits of magnetization preparation by ensuring adequate sampling density throughout the entire k-space volume
3Manufacturing precision
If imaging time is extended to achieve high-resolution volumetric images, then manufacturing precision is improved, but loss of time increases
Solution Approach 1:
The patent implements partial oversampling of k-space by concentrating sampling efforts at the center region and using fewer samples toward the periphery. This partial action approach achieves adequate image resolution for clinical plaque assessment without requiring complete high-resolution sampling of the entire k-space, thereby reducing imaging time while maintaining diagnostic quality
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 system achieves optimal background suppression and reduced motion artifacts, resulting in high-quality, motion-insensitive 3D images of carotid vessel walls with improved imaging efficiency and robustness against patient movement.
Implementation Method 1
magnetic resonance imaging (MRI) system configured to provide a 3D imaging sequence for improved imaging of a vessel wall
Implementation Method 2
The 3D imaging sequence includes a magnetization preparation sequence for suppression of both blood and fat signals
Implementation Method 3
a stack-of-stars (SoS) k-space sampling technique to obtain image data that oversamples image data near the Kz axis in k-space
Data Source
AI summary
A magnetic resonance method and system are provided for providing improved 3D imaging of blood vessels and the like, which provides suppression of both blood and fat signals and is insensitive to subject motion, thereby facilitating improved visualization of vessel walls. The image data pulse sequence includes a plurality of pulse series, where each series includes a dark-blood sequence, a fat-suppression sequence, and a data readout sequence. Each data readout sequence samples a particular radial direction within each partition (Kz value) that passes through the Kz axis, and different radial orientations are sampled in subsequent series to provide a stack-of-stars sampling scheme.