Ultrafast MRI System Using 3D Coil Array and Gradient Reversal
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Solution Overview
Problem
Conventional MRI systems face limitations in achieving rapid 3D spatial encoding due to reliance on magnetic gradient switching and RF pulses, leading to noise, image degradation, and restricted acceleration factors, which hinder the acquisition of high-quality images with sufficient signal-to-noise ratio (SNR) and resolution.
Innovation Solution
A novel MRI system employing a 3D array of small MR signal receiving coils that acquire signals from the entire imaging volume without additional RF pulses or gradient reversals, utilizing a steady gradient field and spatial sensitivity encoding to generate high-quality 3D images, allowing for improved SNR and reduced noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetic gradient switching and RF pulses are used for spatial encoding, then spatial encoding is achieved, but image degradation and noise increase
Solution Approach 1:
The patent extracts and eliminates the harmful gradient switching and RF pulses from the imaging process. By using a single RF excitation pulse followed by gradient reversals for spatial encoding, the system removes the need for repeated gradient switching that causes noise and image degradation, while maintaining spatial encoding capability through the gradient reversal technique
Solution Approach 2:
The patent inverts the conventional approach by using gradient reversals instead of gradient switching. Instead of applying successive gradients in different directions, the system applies a single gradient that is repeatedly reversed, achieving spatial encoding through the inversion mechanism rather than through sequential gradient application
2Productivity
If gradient reversals are used for spatial encoding, then acquisition speed is increased, but sensitivity to susceptibility changes and magnetic field inhomogeneities increases
Solution Approach 1:
The patent merges parallel MRI techniques with gradient reversal encoding. By combining multiple receiver coils that capture spatially encoded signals simultaneously with gradient reversals, the system achieves fast acquisition while using signal processing algorithms to compensate for susceptibility artifacts and field inhomogeneities
Solution Approach 2:
The patent employs signal processing and reconstruction algorithms that act as feedback mechanisms to correct for susceptibility changes and field inhomogeneities. The system captures the effects of these variations and uses computational methods to compensate, maintaining reliability while achieving fast acquisition speeds
3Productivity
If parallel MRI with multiple receiver coils is used, then acquisition speed is increased, but signal-to-noise ratio is reduced
Solution Approach 1:
The patent changes the operational parameters of the receiver coils by optimizing their configuration, spacing, and sensitivity profiles. By carefully selecting and positioning multiple coils with complementary spatial sensitivities, the system maintains high signal-to-noise ratio while achieving parallel imaging acceleration
Solution Approach 2:
The patent creates a composite receiver coil array where multiple coils with different spatial sensitivities work together as an integrated system. This composite arrangement allows the system to capture sufficient signal from multiple sources simultaneously, maintaining signal-to-noise ratio while enabling fast parallel acquisition
4Measurement precision
If hybrid gradient and spatial sensitivity encoding is used, then ultimate signal-to-noise is achieved, but device complexity increases
Solution Approach 1:
The patent segments the encoding function between gradient reversals and receiver coil spatial sensitivities. By dividing the spatial encoding task into these two components, the system achieves high signal-to-noise ratio through the combined effect while managing complexity through functional separation rather than requiring a single complex encoding mechanism
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 enables faster image acquisition, higher resolution, and significantly improved SNR, making it possible to acquire images with a much lower main magnetic field strength, potentially eliminating the need for a traditional MRI magnet and reducing acoustic noise, while maintaining image quality comparable to conventional systems.
Implementation Method 1
a magnet configured to generate a main magnetic field B0 in an imaging volume
Implementation Method 2
a gradient field generator configured to generate a steady gradient field g in the imaging volume
Implementation Method 3
a radio-frequency (RF) pulse generator configured to apply an excitation RF pulse to the imaging volume
Implementation Method 4
Each of the receiver coils is configured to simultaneously receive RF energy from the entire imaging volume during MR signal acquisition
Data Source
AI summary
A Magnetic Resonance Imaging (MM) system, called ULTRA (Unlimited Trains of Radio Acquisitions), can operate with essentially no magnetic gradient reversals. Each of a multitude of small receiver coils arranged in a 3D array around the imaging volume simultaneously acquires MR signal from the entire volume. This greatly increases the rate of MR signal acquisition and allows a full MR image to be reconstructed in as little as 1 millisecond. Both electrical and audible noise is greatly reduced.