Orthogonal radio frequency coil structure for head magnetic resonance imaging

Abstract

An orthogonal radio frequency coil structure for magnetic resonance imaging of the head is described. The radio frequency coil is composed of a plurality of convex coils and a plurality of spiral coils arranged orthogonally. The coils are attached to a supporting inner shell. The convex coils and spiral coils are arranged on a cylindrical, spherical, curved, or conical surface and are used to receive magnetic resonance echo signals. The coils of the convex coils and spiral coils arranged on the cylindrical, spherical, or curved surface are unevenly distributed with alternating density to improve the uniformity of the radio frequency magnetic field and the signal-to-noise ratio of the radio frequency coil. The present invention effectively improves the uniformity of the radio frequency magnetic field and the signal-to-noise ratio of the radio frequency coil through the coil shape design and the uneven distribution of winding spacing.

Description

Technical field

[0001] The present invention relates to the field of magnetic resonance technology for medical diagnosis, and in particular to an orthogonal radio frequency coil structure for head magnetic resonance imaging. [Background Technology]

[0002] Magnetic resonance imaging (MRI) boasts unmatched advantages over other imaging techniques, such as high spatial resolution and excellent spatial localization, and is widely used in numerous fields, including scientific research and clinical medicine. Existing MRI systems primarily consist of a main magnet, gradient coils, radiofrequency coils, computer systems, and other auxiliary equipment. The radiofrequency coil is a key component of an MRI system, consisting of a transmitting coil and a receiving coil. The receiving coil receives signals from the region of interest with a high signal-to-noise ratio. The closer the receiving coil is to the examination site, the stronger the received signal, while the smaller the coil, the lower the noise received. Therefore, specialized coils are often developed for different imaging sites, such as head coils, joint coils, and cardiac coils.

[0003] In low-field MRI applications, since magnetic field strength is much lower than in medium- and high-field systems, improving the signal-to-noise ratio (SNR) of MRI signals by optimizing the RF coil structure is particularly important. Traditional orthogonal RF coil structures typically consist of a receiving coil combining a toroidal coil and a saddle coil. Using both a toroidal coil and a saddle coil simultaneously allows for the simultaneous acquisition of two-channel MRI signals, increasing the image's SNR by a factor of √2. However, current saddle coils are typically manufactured using a regular shape and uniform winding method, making it difficult to further improve the coil's detection sensitivity and uniformity. [Summary of the invention]

[0004] The present invention aims to solve the above-mentioned problems and provides an orthogonal RF receiving coil structure for an MRI head, which aims to maximize the uniformity of the coil magnetic field and the signal-to-noise ratio. The structure effectively improves the uniformity of the RF magnetic field and the signal-to-noise ratio of the RF coil by non-uniformly distributing the coil winding spacing.

[0005] To achieve the above objectives, the present invention provides an orthogonal radio frequency coil structure for head magnetic resonance imaging. The radio frequency coil is composed of a plurality of convex coils and a plurality of spiral coils arranged orthogonally. The convex coils and spiral coils are attached to a supporting inner shell and are used to receive magnetic resonance echo signals from the human brain.

[0006] The convex coil is composed of an upper semicircular arc coil and a lower saddle coil. The convex coil is oriented in the Y-axis direction and is used to receive horizontal magnetic resonance signals in the imaging area. The spiral coil is oriented in the Z-axis direction and is used to receive vertical magnetic resonance signals in the imaging area. The magnetic fields generated by the two coils are perpendicular to each other.

[0007] The support inner shell is formed by an upper half and a lower half to form a cavity for accommodating the human head. The upper half is one of a hemispherical, arched, and conical shape, and the lower half is one of a cylindrical, elliptical, or polygonal shape. The end near the neck is open and the end near the top of the head is closed.

[0008] The outer surface of the supporting inner shell is a cylindrical surface, a spherical surface, an arc surface or a conical surface. The convex coils and the spiral coils arranged on the cylindrical surface, the spherical surface, the arc surface or the conical surface have a smaller coil arrangement spacing in the lower half of the head, and a larger coil arrangement spacing in the upper half of the head. The coils are unevenly distributed in a sparse and dense manner, forming an irregular streamlined arrangement. The density is obtained with the goal of maximizing the uniformity of the coil magnetic field and maximizing the signal-to-noise ratio.

[0009] The diameters of the convex coil and the spiral coil gradually decrease from the open end to the closed end of the supporting inner shell, and the size and position of the coils can be adjusted according to actual imaging quality.

[0010] The contribution of the present invention is that it effectively solves the problems of weak receiving capability, limited imaging area effect, and poor imaging quality of existing radio frequency receiving coils. The present invention distributes the radio frequency coils orthogonally in convex and spiral shapes, and distributes the turns of the convex coils and spiral coils unevenly in a sparse and dense alternating manner, thereby effectively improving the uniformity of the radio frequency magnetic field and improving the signal-to-noise ratio of the radio frequency coil, thereby achieving maximum coil magnetic field uniformity and maximum signal-to-noise ratio.

Brief Description of the Drawings

[0011] Figure 1 It is a schematic diagram of the three-dimensional structure of the orthogonal radio frequency coil of the present invention.

[0012] Figure 2 It is a three-dimensional schematic diagram of the saddle-shaped radio frequency coil supporting inner shell of the present invention.

[0013] FIG3 is a schematic diagram of the structure of a convex radio frequency coil of the present invention, wherein: Figure 3A A three-dimensional schematic diagram. Figure 3B It is a plan diagram.

[0014] FIG4 is a schematic diagram of the helical coil structure of the present invention, wherein: Figure 4A A three-dimensional schematic diagram. Figure 4B Schematic diagram of coil spacing. [Specific implementation method]

[0015] The following examples are provided to further explain and illustrate the present invention and do not constitute any limitation to the present invention.

[0016] See Figure 1 、 Figure 2 , Figure 1The orthogonal radio frequency coil structure for head magnetic resonance imaging of the present invention is an orthogonal radio frequency coil structure for head magnetic resonance imaging, which is composed of a convex coil 10 and a spiral coil 20 orthogonally combined. Figure 2 The supporting inner shell 30 is composed of an upper half 31 and a lower half 32 to form a cavity for accommodating the human head. The upper half 31 is one of hemispherical, arched, and conical shapes, and the lower half 32 is one of cylindrical, elliptical, or polygonal shapes. It is open at one end near the neck and closed at one end near the top of the head. The outer surface of the supporting inner shell 30 is a cylindrical, spherical, curved, or conical surface 33.

[0017] like Figure 3A 、 Figure 3B As shown, the convex coil 10 has a semicircular arc coil at the top and a saddle coil at the bottom. The coils of the convex coil 10 are unevenly distributed, with alternating density, to improve the uniformity of the RF magnetic field and the signal-to-noise ratio of the RF coil. The convex coil 10 can be mounted on a cylindrical, spherical, arc-shaped, or conical surface for receiving magnetic resonance signals. The cylindrical surface can be a circular cylinder, an elliptical cylinder, or a polygonal prism. In this embodiment, the convex coil 10 is mounted on a curved surface with a spherical upper half and a cylindrical lower half. The cylindrical and spherical surfaces serve as the housing for the convex coil 10, and their internal spaces form the space required for head imaging. To improve the uniformity of the RF magnetic field and the signal-to-noise ratio of the RF coil, the coils of the convex coil 10 on the cylindrical and spherical surfaces are unevenly distributed, with alternating density, to form an irregular, streamlined, and surrounding arrangement. This embodiment uses the convex coil 10 distributed on the cylindrical and spherical surfaces as an example. The convex coil 10 can be appropriately curved in the areas corresponding to the ears on its left and right sides. This curved path is optimized and calculated to maximize the coil's magnetic field uniformity and signal-to-noise ratio. The coil spacing gradually decreases in the area corresponding to the top of the head, significantly improving the coil's signal-to-noise ratio. In the area corresponding to the lower part of the head, the turns of the convex coil 10 are spaced more closely together, while the coil spacing at the top of the head is more sparse. This advantage is that the coils at the top of the head are closer to the brain, and the sparse distribution of the coils prevents the concentration of magnetic field lines, which can lead to excessive local magnetic fields, thereby improving magnetic field uniformity. In areas farther from the top of the head, the smaller coil spacing allows for the concentration of magnetic field lines, enhancing magnetic field uniformity at the brain. The density and number of coil turns at different coil locations can be optimized based on magnetic field uniformity and signal-to-noise ratio. The convex coil 10 is used to receive horizontal magnetic resonance echo signals and can be arranged symmetrically, either left-right or front-to-back, relative to the head. The coil size and position of the convex coil 10 can be adjusted based on the actual imaging quality.

[0018] like Figure 4A 、 Figure 4BAs shown, the turns of the helical coil 20 are distributed in a spiral shape, and the turns of the helical coil 20 are unevenly distributed in a sparse and dense manner to improve the uniformity of the radio frequency magnetic field and the signal-to-noise ratio of the radio frequency coil. The helical coil 20 can be set on a cylindrical surface, which can be a cylindrical surface, an elliptical cylindrical surface or a polygonal cylindrical surface, for receiving magnetic resonance signals. In this embodiment, the convex coil 10 is set on a cylindrical surface. The cylindrical surface is a shell supported by the helical coil 20, and its inner cavity space forms the space required for head imaging. In order to improve the uniformity of the radio frequency magnetic field and the signal-to-noise ratio of the radio frequency coil, the turns of the helical coil 20 distributed on the cylindrical surface are unevenly distributed in a sparse and dense manner to form an irregular streamlined surrounding arrangement. This embodiment takes the helical coil 20 distributed on the cylindrical surface as an example. As Figure 4A 、 Figure 4B As shown, the coil spacing is larger in the area corresponding to the top of the human head. The coil spacing gradually shrinks in the area corresponding to the top of the human head, and the diameter of the coil gradually becomes smaller, so that each coil is as close to the head as possible to improve the signal-to-noise ratio of the coil. The density and number of wire turns at different positions of the coil can be optimized and calculated based on the magnetic field uniformity and signal-to-noise ratio. The spiral coil 20 is used to receive vertical magnetic resonance echo signals and can be arranged symmetrically left and right or front and back relative to the human head. The coil size and position of the spiral coil 20 can be adjusted according to the actual imaging quality.

[0019] The present invention forms an orthogonal radio frequency coil structure for head magnetic resonance imaging by arranging convex coils 10 and solenoid coils 20 that are unevenly distributed in a sparse and dense manner. In this embodiment, while ensuring a coil bandwidth >15kHz and using a sphere with a radius of 150mm as the target area, the orthogonal coils of the present invention achieve an improvement in signal-to-noise ratio of more than 50% and an improvement in magnetic field uniformity of more than 1 times compared to the receiving coils composed of the orthogonal combination of traditional solenoid coils and saddle coils. Overall, the optimized orthogonal coils have significantly improved performance in all aspects compared to traditional orthogonal coils. A performance comparison of the optimized orthogonal coils of the present invention and traditional orthogonal coils is shown in Table 1.

[0020] Table 1 Performance comparison between optimized orthogonal coil and traditional orthogonal coil

[0021]

[0022] Thus, the present invention provides an orthogonal radio frequency coil structure for head magnetic resonance imaging by arranging convex coils 10 and spiral coils 20 that are unevenly distributed in a sparse and dense manner to form an orthogonal combination. This can effectively improve the uniformity of the radio frequency magnetic field and simultaneously improve the signal-to-noise ratio of the radio frequency coil, thereby maximizing the coil magnetic field uniformity and the signal-to-noise ratio, thereby achieving the best detection effect of the head magnetic resonance signal.

[0023] Although the present invention is disclosed through the above embodiments, the protection scope of the present invention is not limited thereto. Without departing from the concept of the present invention, any deformation or replacement of the above components shall fall within the scope of the claims of the present invention.

Claims

1. An orthogonal radio frequency coil structure for head magnetic resonance imaging, characterized in that: The radio frequency coil is composed of a plurality of convex coils (10) and a plurality of spiral coils (20) distributed orthogonally. The convex coils (10) and the spiral coils (20) are attached to a supporting inner shell (30) and are used to receive magnetic resonance echo signals of the human brain. The outer surface of the supporting inner shell (30) is a cylindrical surface, a spherical surface, a curved surface or a conical surface (33). The convex coils (10) and the spiral coils (20) arranged on the cylindrical surface, the spherical surface, the curved surface or the conical surface (33) have a smaller coil arrangement spacing in the lower half (32) of the head and a larger coil arrangement spacing in the upper half (31) of the head. The coils are unevenly distributed in a sparse and dense alternating manner to form an irregular streamlined arrangement. The density is obtained by maximizing the uniformity of the coil magnetic field and maximizing the signal-to-noise ratio.

2. The orthogonal radio frequency coil structure for head magnetic resonance imaging according to claim 1, wherein: The convex coil (10) is composed of an upper semicircular arc coil and a lower saddle coil. The convex coil has an axial direction in the Y-axis direction and is used to receive magnetic resonance signals in the horizontal direction of the imaging area. The spiral coil (20) has an axial direction in the Z-axis direction and is used to receive magnetic resonance signals in the vertical direction of the imaging area. The magnetic fields generated by the two coils are perpendicular to each other.

3. The orthogonal radio frequency coil structure for head magnetic resonance imaging according to claim 1, wherein: The supporting inner shell (30) is formed integrally by an upper half (31) and a lower half (32) to form a cavity for accommodating a human head, wherein the upper half (31) is in the shape of a hemisphere, an arch, or a cone, and the lower half (32) is in the shape of a cylinder, an elliptical cylinder, or a polygonal column, with an end near the neck being open and an end near the top of the head being closed.

4. The orthogonal radio frequency coil structure for head magnetic resonance imaging according to claim 3, wherein: The convex coil (10) and the spiral coil (20) have coil diameters that gradually decrease from the open end to the closed end of the supporting inner shell (30), and the size and position of the coils can be adjusted according to actual imaging quality.

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