3D MRI System Using Steady Gradient and Coil Array
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Solution Overview
Problem
Conventional MRI techniques face limitations in achieving high signal-to-noise ratio (SNR) and rapid image acquisition due to reliance on gradient reversals and RF pulses, which introduce noise and require multiple magnetic gradients, leading to image degradation and increased noise levels.
Innovation Solution
A 3D MRI system using a multitude of small receiver coils arranged around the imaging volume, where spatial encoding is achieved with a steady magnetic gradient and initial RF pulse, allowing for refocusing and additional echo creation without frequent gradient reversals or RF pulses, thereby reducing noise and enhancing SNR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If gradient reversals and RF pulses are used for spatial encoding, then image acquisition can be performed, but noise levels increase and signal-to-noise ratio decreases
Solution Approach 1:
The imaging volume is divided into multiple slices that can be acquired simultaneously or sequentially using different coil elements, allowing parallel acquisition that reduces total scan time without requiring frequent gradient reversals
Solution Approach 2:
The patent introduces a temporal dimension to the encoding scheme by using time-varying coil sensitivities and multiple time points to encode spatial information, replacing the need for gradient reversals in the spatial encoding process
2Measurement precision
If multiple magnetic gradients are applied for spatial encoding, then image resolution can be achieved, but image degradation occurs due to noise and inhomogeneities
Solution Approach 1:
Multiple coil elements create redundant copies of the signal from different spatial locations, and these copies are combined through sensitivity encoding to reconstruct the image, providing robustness against noise and inhomogeneities
Solution Approach 2:
The system exploits changes in coil sensitivity parameters over time and space, using the temporal evolution of induced signals to encode spatial information without requiring strong gradient fields
3Object-affected harmful factors
If conventional MRI systems use strong magnets for high signal-to-noise ratio, then image quality improves, but system complexity and cost increase
Solution Approach 1:
The receiver system is segmented into multiple independent coil elements, each contributing to the overall signal-to-noise ratio through parallel acquisition and sensitivity encoding, replacing the need for a single strong magnet
Solution Approach 2:
Multiple coil signals are merged through sensitivity encoding algorithms to produce the final image, combining the weak signals from multiple coils to achieve the same or better signal-to-noise ratio that would require a strong magnet in conventional systems
4Productivity
If gradient switching is performed frequently for rapid imaging, then acquisition speed increases, but acoustic noise increases
Solution Approach 1:
Multiple coil elements create redundant signal copies that can be acquired simultaneously, enabling rapid imaging without the need for frequent gradient switching that generates acoustic noise
Solution Approach 2:
The system uses periodic RF excitation pulses combined with time-varying coil sensitivities to encode spatial information over time, replacing the need for frequent gradient reversals that generate acoustic noise
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 significantly improved SNR and faster image acquisition with lower magnetic field strengths, allowing for higher resolution images and reduced noise, potentially eliminating the need for strong magnets and minimizing acoustic noise, resulting in images comparable to conventional MRI systems but acquired in much shorter times.
Implementation Method 1
A 3D MRI system uses a main magnetic field to polarize nuclear spins in an imaging volume
Implementation Method 2
spatial encoding is achieved with a steady magnetic gradient
Implementation Method 3
spatial encoding is achieved with a steady magnetic gradient and initial RF pulse, allowing for refocusing and additional echo creation
Data Source
AI summary
Magnetic Resonance Imaging (MRI), which is given the acronym ULTRA (Unlimited Trains of Radio Acquisitions), allows simultaneous MR signal acquisition from the entire object volume in each of a multitude of very small receiver coils arranged in a 3D array around the imaging volume, except for gradient reversals and/or RF pulses for refocusing spins into echoes. This permits a rate of MR signal acquisition that is greatly increased (e.g., 256 times) compared with known existing techniques, with a full 3D image constructed in as little as 1 millisecond. Furthermore, noise—both audible and electrical—is substantially reduced. Clinical imaging can be completed in seconds or less, with good signal-to-noise ratio; signal-to-noise ratio further increases by reducing or eliminating RF noise due to gradient switching; real-time functional MRI can be on millisecond timescales; high quality imaging of thorax and abdomen can be in a single breath hold; ands; and audible noise and vibration are greatly reduced.