MRI RF Coil with Uneven Meander Spacing for Comfortable Bore
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Solution Overview
Problem
Tunnel-type MRI apparatuses face challenges in creating a comfortable examination space for large subjects and those with claustrophobia due to the limited internal diameter, which increases manufacturing costs when attempting to enlarge the static magnetic field magnet, and existing volume antennas do not accommodate the human body shape effectively.
Innovation Solution
An RF coil with a hollow cylindrical outer conductive element and internal strip-shaped conductive elements made of meandering or straight lines, where the distances between these elements and the outer conductive element are uneven, providing a larger internal space without increasing the size of the static magnetic field magnet, and featuring capacitors connected in series for uniform sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the internal diameter of the static magnetic field magnet is increased to secure a comfortable examination space, then the examination space is improved, but the manufacturing cost increases markedly
Solution Approach 1:
The invention divides the examination space optimization into two independent parts: maintaining the static magnetic field magnet size while optimizing the RF coil internal space. The RF coil is segmented into an outer conductive element and inner conductive elements with specific spacing, allowing the examination space to be enlarged without changing the magnet dimensions, thereby avoiding increased manufacturing costs.
Solution Approach 2:
The invention applies nesting by placing inner conductive elements inside the hollow cylindrical outer conductive element of the RF coil. This nested structure allows the RF coil to provide a larger internal examination space while maintaining a compact outer diameter that fits within the existing static magnetic field magnet, thus avoiding the need to enlarge the magnet.
2Ease of manufacture
If conventional volume antennas with equal spacing are used, then the manufacturing is simple, but they do not accommodate the human body shape effectively and provide limited sensitivity regions
Solution Approach 1:
The invention applies local quality by setting different spacing intervals for the inner conductive elements along the axial direction of the RF coil. The spacing is configured to be smaller in regions corresponding to the shoulder width of the human body and larger in other regions, allowing the antenna to accommodate the human body shape effectively while maintaining manufacturing feasibility.
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 configuration secures a comfortable examination space in tunnel-type MRI apparatuses without increasing manufacturing costs or sacrificing performance, enhancing sensitivity and accommodating the human body shape by adjusting the internal space, particularly at the shoulder level.
Implementation Method 1
each strip-shaped conductive element has electrically one turning conductive element part, one or more capacitors connected to the conductive element in series, and a feeding and receiving means connected in parallel with one of the capacitors, and resonates at a desired resonance frequency
Implementation Method 2
one or more capacitors connected to the conductive element in series, and a feeding and receiving means connected in parallel with one of the capacitors
Implementation Method 3
imaging of a subject is attained by irradiating the subject stayed in a uniform static magnetic field generated by a static magnetic field magnet with electromagnetic waves to induce excitation of nuclear spins in the subject, receiving electromagnetic waves generated by the nuclear spins
Data Source
AI summary
There is provided a technique for securing a comfortable examination space in a tunnel type MRI apparatus without increasing the manufacturing cost of the MRI apparatus and sacrificing performance thereof. In an RF coil provided with a hollow-shaped outer conductive element and a strip-shaped conductive element disposed along the outer conductive element in the axial direction, meander lines constituting the strip-shaped conductive element are disposed at uneven distances from the outer conductive element to secure an internal space. In order to obtain uniform sensitivity at the center of the RF coil, the strip-shaped conductive element is constituted with N of connected meander lines, and length of the strip-shaped conductive element is adjusted so that, in the strip-shaped conductive element resonating at resonance frequency of the antenna, nodes are formed in a number of (M+1)×N−1, wherein M is 0 or a natural number of 1 or larger.