RF Volume Coil Segmentation for MRI Access and Homogeneity
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Solution Overview
Problem
In magnetic resonance examination systems, birdcage resonators provide homogeneous radio frequency magnetic excitation fields but pose challenges in accessing the subject and positioning auxiliary devices due to the increasing complexity with more rungs, restricting access and space for monitoring or therapy.
Innovation Solution
A radio frequency volume coil design with a pair of conductive loop members and axially arranged conductive members that create an installation space, allowing improved access and positioning of auxiliary devices while maintaining homogeneity of the magnetic excitation field and signal sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the number of rungs in a birdcage coil is increased to improve field homogeneity, then the radio frequency magnetic excitation field homogeneity is improved, but the access to the subject and space for auxiliary devices is restricted
Solution Approach 1:
The coil structure is divided into two separate conductive loop members instead of a single continuous structure with multiple rungs. This segmentation maintains field homogeneity through the distributed capacitor configuration while opening up access spaces between the two loop members for subject access and auxiliary device placement.
Solution Approach 2:
The invention transitions from a traditional planar birdcage structure to a three-dimensional configuration with two spaced loop members. This dimensional change creates volumetric access spaces while maintaining the electrical properties needed for homogeneous field generation through the specific capacitor arrangement.
2Manufacturing precision
If the number of rungs in a birdcage coil is increased to improve field homogeneity, then the radio frequency magnetic excitation field homogeneity is improved, but the space for auxiliary devices is reduced
Solution Approach 1:
By segmenting the coil into two separate loop members, the invention creates volumetric spaces between and around the loops that can accommodate auxiliary devices. This segmentation maintains field homogeneity through the distributed capacitor configuration while providing necessary space for additional equipment.
Solution Approach 2:
The two conductive loop members are positioned to create nested or interlaced configurations that maximize the use of available space. This nesting approach allows auxiliary devices to be placed in the spaces between the loops while maintaining the overall compact structure needed for field homogeneity.
3Ease of operation
If the birdcage coil structure is simplified to improve access and space, then the access to subject and space for auxiliary devices is improved, but the homogeneity of the magnetic excitation field may be compromised
Solution Approach 1:
The invention changes the electrical parameters by introducing distributed capacitors at specific positions on the two loop members. This parameter change allows the simplified two-loop structure to generate homogeneous magnetic fields through resonant operation, compensating for the reduced structural complexity while maintaining field uniformity.
Solution Approach 2:
The two conductive loop members serve multiple functions: they generate the homogeneous magnetic field through their resonant operation, they create access spaces for subject positioning, and they provide volumetric space for auxiliary devices. This multi-functionality resolves the contradiction between structural simplification and field homogeneity.
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 design enhances access to the subject and accommodates auxiliary devices close to the coil, increasing comfort and operational efficiency during examinations by providing additional space and maintaining the homogeneity of the radio frequency magnetic excitation field.
Implementation Method 1
a pair of conductive loop members spaced along a common longitudinal axis and a plurality of axially arranged conductive members electrically connected to at least one of the conductive loop members... generating a radio frequency magnetic excitation field B1
Implementation Method 2
They are usually operated in resonance at a radio frequency corresponding to the Larmor frequency, which depends on the strength of the static magnetic field B0 and the gyromagnetic magnetic ratio of the species of nuclei under consideration
Data Source
Figure 1
Figure 2a~2b
Figure 3a~3b
AI summary
A radio frequency volume coil (136; 236) for use in a magnetic resonance examination system (10), comprising: - a radio frequency shield (148; 248), - a pair of radio frequency conductive loop members (138; 238) spaced along a common longitudinal axis (140; 240), - a plurality of axially arranged radio frequency conductive members electrically connected to at least one of the radio frequency conductive loop members (138; 238), wherein - at least two axially arranged radio frequency conductive members electrically interconnect the radio frequency conductive loop members (138; 238) as interconnecting members (144; 244), and - at least two of the axially arranged radio frequency conductive members are axially arranged in an aligned manner at an azimuthal position within the range between azimuthal positions of the at least two interconnecting members (144; 244), and electrically serve as shield-connecting members (146; 246) for one of the two radio frequency conductive loop members (138; 238) to the radio frequency shield (148; 248), - at least one installation space (152; 252) within an inner volume of the radio frequency volume coil (136; 236) that is accessible from outside the radio frequency volume coil (136; 236) at least in a radial direction (56) within the range between the two different azimuthal positions of the two interconnecting members (144; 244), and within a range of the axial direction between axial positions of ends of the shield-connecting members (146; 246) that are distal to the radio frequency conductive loop member (138; 238) they are connected to; and - a magnetic resonance examination system (10) comprising such radio frequency volume coil (136; 236).