Split DC Loop RF Coils for MRI iPRES Shimming
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Solution Overview
Problem
Current MRI technologies face challenges in achieving homogeneous magnetic fields, particularly with strong localized inhomogeneities, as conventional shimming methods like spherical harmonic coils are limited in correcting high-order distortions and require additional space, reducing signal-to-noise ratio and increasing RF power consumption.
Innovation Solution
The integration of parallel reception, excitation, and shimming (iPRES) using a new coil design that allows RF current and direct current to flow simultaneously in the same coil elements, enabling effective B0 shimming with split DC loops, which increases spatial resolution and flexibility, and eliminates the need for separate shim coils, thereby improving signal-to-noise ratio and reducing electromagnetic interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate shim coils are used for B0 shimming, then shimming capability is improved, but device complexity and space requirements increase
Solution Approach 1:
The patent combines B0 shimming function with RF coil elements by integrating DC loops directly into the RF coil structure. Each RF coil element incorporates one or more DC loops that can carry direct current to generate localized B0 fields for shimming, eliminating the need for separate shim coil arrays and reducing overall system complexity while maintaining effective shimming capability
Solution Approach 2:
The RF coil elements are designed to perform multiple functions simultaneously: RF signal transmission/reception and B0 field shimming. The DC loops integrated into the RF coil elements can carry DC current for shimming while the same structural elements handle RF operations, making the coil array universal and multi-functional
2Reliability
If separate shim coils are placed within the RF coil array, then shimming is achieved, but signal-to-noise ratio decreases due to RF damping and electromagnetic interference
Solution Approach 1:
By merging the shimming function into the RF coil elements themselves rather than placing separate shim coils within the array, the patent eliminates the problematic interaction between separate RF and shim coil arrays. The integrated DC loops are part of the RF coil structure, so there is no RF damping or electromagnetic interference between separate arrays, preserving signal-to-noise ratio while achieving effective shimming
3Stability of the object's composition
If spherical harmonic coils are used for shimming, then homogeneous B0 field is improved, but ability to correct high-order localized distortions is limited
Solution Approach 1:
The patent segments the shimming function into multiple independent DC loops distributed across different RF coil elements. Each DC loop can be independently controlled to generate localized B0 field corrections, enabling the system to address high-order localized distortions that cannot be corrected by global spherical harmonic coils alone, while still maintaining overall field homogeneity
4Measurement precision
If RF coil elements have split DC loops, then spatial resolution and flexibility for shimming are improved, but device complexity increases
Solution Approach 1:
The DC loops are segmented into multiple smaller loops within each RF coil element, with each loop independently controllable. This segmentation provides finer spatial resolution for localized shimming corrections and greater flexibility in addressing specific field inhomogeneities, while the modular integration into existing RF coil elements keeps the complexity increase manageable
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 provides more effective B0 shimming than conventional methods, allowing for uniform magnetic fields across biological tissue, increased signal-to-noise ratio, and reduced RF power consumption by integrating shimming functions into the RF coil array, enhancing imaging quality and efficiency.
Implementation Method 1
respective coil elements having split DC loops and configured to be simultaneously operative in both (i) an RF mode for at least one of transmit or receive and (ii) a direct current (DC) mode with DC current flow in the respective coil elements to generate local B0 magnetic fields
Data Source
AI summary
Systems, methods and devices are configured for integrated parallel reception, excitation, and shimming (iPRES) with RF coil elements with split DC loops. Parallel transmit/receive (which can include B1 shimming and/or parallel imaging capabilities) and B0 shimming employ the same set of localized coils or transverse electromagnetic (TEM) coil elements, with each coil or TEM element working in both an RF mode (for transmit/receive and B1 shimming) and a direct current (DC) mode (for B0 shimming) simultaneously. Both an RF and a DC current (in split DC loops) can flow in the same coil element simultaneously but independently with no electromagnetic interference between the two modes.