RF Spatial Encoding in MRI Without B0-Gradient Coils
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Solution Overview
Problem
Conventional MRI systems are costly and inaccessible due to the high financial burden of infrastructure and noise generation by B0-gradient coils, limiting their availability to wealthy institutions.
Innovation Solution
Implementing a method for magnetic resonance imaging using frequency-modulated RF pulses to encode spatial information, eliminating the need for B0-gradient coils by utilizing RF coils for phase encoding, enabling silent and cost-effective MRI systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional B0-gradient coils are used for spatial encoding in MRI, then spatial encoding capability is achieved, but the system requires significant infrastructure including space, power, water cooling, and produces noise
Solution Approach 1:
The patent extracts the spatial encoding function from the conventional B0-gradient coil system and implements it using only RF pulses. By removing the B0-gradient coils entirely and using frequency-modulated RF pulses to create B1 gradients, the system eliminates the need for complex infrastructure while maintaining spatial encoding capability through alternative physical mechanisms
Solution Approach 2:
The patent replaces the mechanical/electrical B0-gradient coil system with an electromagnetic RF-based system. Instead of using physical gradient coils that require power supplies and cooling systems, the invention uses frequency-modulated RF pulses that generate spatially varying B1 fields, substituting a simpler electromagnetic approach for the complex mechanical-electrical system
2Device complexity
If B0-gradient coils are removed to reduce infrastructure needs, then cost and complexity are reduced, but spatial encoding capability is lost
Solution Approach 1:
The patent changes the fundamental parameter used for spatial encoding from B0 field gradients to B1 field gradients. By applying frequency-modulated RF pulses that create spatially varying B1 amplitudes and phases, the system achieves spatial encoding through parameter modulation of the RF field rather than through B0 field gradients, maintaining encoding capability without infrastructure
Solution Approach 2:
The RF pulse system performs multiple functions: it provides both the excitation function and the spatial encoding function that were traditionally separated in conventional MRI. The frequency-modulated RF pulses simultaneously excite spins and encode spatial information through their spatially varying amplitude and phase profiles, eliminating the need for separate gradient coil systems
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 reduces the cost and infrastructure requirements of MRI systems, allowing for widespread distribution and silent imaging, particularly beneficial for pediatric patients and lower-cost, portable systems.
Implementation Method 1
frequency-modulated RF pulses to generate a B1 RF gradient for spatial encoding of magnetic resonance data
Implementation Method 2
utilizing adiabatic full-passage pulses and hyperbolic secant pulses in spin-echo sequences
Implementation Method 3
Magnetic resonance imaging permits robust, high-resolution imaging with tunable image contrast that is free of ionizing radiation
Data Source
AI summary
Radio frequency (“RF”) gradient based magnetic resonance imaging (“MRI”) is provided by establishing a gradient in the RF transmit (B1) field using frequency-modulated RF pulses. A difference between the time-bandwidth product of the frequency-modulated RF pulses can be varied to provide impart different phases to magnetic resonance signals, where these different phases provide phase encoding of the acquired data. The time-bandwidth product difference can be created and varied by changing the pulse duration of one frequency-modulated RF pulse relative to the other while keeping the bandwidth of the pulses constant.