A radio frequency coil control system

Abstract

The invention relates to the technical field of radio frequency coil control systems, and proposes a radio frequency coil control system for improving the signal-to-noise ratio and image quality of infant imaging. The radio frequency coil control system comprises a top antenna module, a head circumference antenna module and a headrest antenna module. The top antenna module comprises at least 7 non-flexible coil units, the head circumference antenna module comprises at least 7 flexible coil units, the headrest antenna module comprises at least 18 non-flexible coil units, the number of coil electrical units is large, a ring-shaped coil unit design is adopted, and the coil unit is distributed in a high density, so that the control system better fits the imaging area of ​​the infant's head.

Description

Technical Field

[0001] The present invention relates to the technical field of radio frequency coil control systems, and in particular to a radio frequency coil control system. Background Art

[0002] Infant MRI is an important tool for clinical diagnosis and research. It has become the first choice for clinical pediatric imaging and plays an important role in the screening, early diagnosis, and staging of infant tumors. The accuracy of diagnosis depends largely on image quality and resolution. Neonatal cranial MRI examinations play an important role in evaluating brain development, diagnosing brain damage, and judging prognosis. However, due to the particularity of newborns, there are certain restrictions and requirements for the selection and use of MRI coils. When obtaining optimal signal reception in early infant brain MRI applications, a tightly fitting coil design is essential to obtain maximum sensitivity from a high-density coil array.

[0003] However, in clinical practice, due to the special physiological structure of newborns, the design and manufacture of special coils require higher technical requirements. In recent years, compared with low-field MRI, 1.5T and 3T equipment are the current mainstream MRI imaging systems. However, compared with the MRI coils used for adults, the number of head coils designed specifically for infants is relatively small, and the number of coil channels is relatively small. The coil structure is simple, mostly birdcage and cylindrical structures. The rigid imaging device and structure are difficult to fit closely to the imaging site, and due to the small number of imaging channels, the image signal-to-noise ratio is greatly lost under high acceleration.

[0004] At present, many hospitals do not have dedicated neonatal coils. Most use adult coils instead of dedicated infant coils, which cannot fit closely to the imaging site. The reduction in noise signal strength limits the ability to obtain high-resolution and signal-to-noise ratio images. In addition, the existing infant coils have a single structure, mostly birdcage and cylindrical structures. Most of them are rigid structures that are difficult to fit closely to the imaging site, and the number of coil unit channels is small. Under high acceleration, the image signal-to-noise ratio is greatly lost, and it cannot support high-acceleration imaging. It is difficult to meet clinical imaging needs. Long-term acquisition is required to maintain a sufficient signal-to-noise ratio, but infants and young children are sedated during scanning to reduce the impact of motion artifacts. Long scanning time will affect the physiological state of infant patients, so strict restrictions are imposed on scanning time. Summary of the invention

[0005] One of the purposes of the present invention is to provide a radio frequency coil control system to improve the signal-to-noise ratio and image quality of infant imaging.

[0006] The technical solution of the present invention is as follows:

[0007] A radio frequency coil control system comprises a head top antenna module, a head circumference antenna module and a headrest antenna module, wherein the head top antenna module comprises at least 7 non-flexible coil units, the head circumference antenna module comprises at least 7 flexible coil units, and the headrest antenna module comprises at least 18 non-flexible coil units.

[0008] Furthermore, each antenna unit in the overhead antenna module and each antenna unit in the headrest antenna module are arranged in a circular structure, and each flexible antenna unit in the head circumference antenna module is arranged linearly.

[0009] Furthermore, the non-flexible coil unit includes a resonant circuit, a matching circuit, an active detuning circuit, a passive detuning circuit, a preamplifier protection circuit, a preamplifier decoupling circuit, a radio frequency trap and a radio frequency choke circuit.

[0010] Furthermore, each of the non-flexible coil units is tuned to 123.3 MHz and matched to 50 ohms.

[0011] Furthermore, the active detuning circuit includes a high-power PIN diode and is arranged at an input end before the preamplifier protection circuit.

[0012] Furthermore, the flexible coil unit includes a flexible high-impedance coaxial line and a preamplifier circuit, and the preamplifier circuit is arranged at the input end of the flexible coil unit.

[0013] Furthermore, each of the non-flexible coil units and the flexible coil unit is arranged as a whole to form a spherical structure.

[0014] Furthermore, the non-flexible coil unit includes a rectangular loop formed by copper skin.

[0015] The working principle and beneficial effects of the present invention are:

[0016] The present invention achieves a higher coil distribution density in the imaging area by reasonably designing 32-channel electrical units, and adopts semi-flexible coils to design the electrical units on the left and right sides, thereby ensuring the flexibility and large bending degree of the coil array, which can fit closely into the imaging area and support 2 times imaging acceleration in the left and right directions, up and down directions, and front and back directions, thereby improving the signal-to-noise ratio and image quality of infant imaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0018] Figure 1 The figure is a schematic diagram of the distribution position of the antenna module (receiving array) in the present invention, and the device in the figure is a head fixing device of an MRI imaging device;

[0019] Figure 2Schematic diagram of the arrangement of numbers CH1-CH7;

[0020] Figure 3 is a schematic diagram of the arrangement numbered CH8-CH14;

[0021] Figure 4 It is a schematic diagram of the arrangement of numbers CH15-CH32;

[0022] Figure 5 This is the circuit diagram of the non-flexible coil unit;

[0023] Figure 6 This is the circuit diagram of the flexible coil unit;

[0024] Figure 7 The noise matrix distribution diagram of different coil arrays;

[0025] Figure 8 This is a schematic diagram of the acceleration capabilities of the coils in each direction;

[0026] Fig. 9 This is the signal-to-noise ratio distribution diagram of different receiving arrays.

[0027] In the figure: 1. The location of the overhead antenna module; 2. The location of the head circumference antenna module; 3. The location of the headrest antenna module. DETAILED DESCRIPTION

[0028] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0029] Embodiment 1

[0030] like Figure 1 As shown, a radio frequency coil control system is mainly used in MRI equipment, including a semi-flexible 32-channel radio frequency receiving coil array for high-field 3T magnetic resonance equipment, which is divided into a head top antenna module, a head circumference antenna module and a headrest antenna module. The three antenna modules are respectively located on the upper side of the head, the left and right sides, and the lower part of the headrest.

[0031] Among them, Figure 2 As shown, the overhead antenna module includes at least 7 non-flexible coil units, numbered CH1-CH7. Figure 3 As shown, the head circumference antenna module includes at least 7 flexible coil units, numbered CH8-CH14. Figure 4 As shown, the headrest antenna module includes at least 18 non-flexible coil units, numbered CH15-CH32.

[0032] In this embodiment, each antenna unit in the overhead antenna module and each antenna unit in the headrest antenna module are arranged in a circular structure, or a hemispherical structure, to adapt to the upper and lower shapes of the human head. The flexible antenna units in the head circumference antenna module are arranged linearly, such as on the same horizontal plane, arranged around the head. All coil units (including each non-flexible coil unit and the flexible coil unit) are arranged as a whole to form a spherical structure, which adapts to the near-spherical load (head area) to accommodate changes in the size of the newborn's head circumference, and also helps to reduce the electromagnetic coupling between the coil and the imaging object.

[0033] Specifically, Figure 5 As shown, the non-flexible coil unit in this embodiment includes but is not limited to a rectangular loop composed of copper foil (left side of the figure), a resonant circuit, a matching circuit, an active detuning circuit, a passive detuning circuit, a preamplifier protection circuit, a preamplifier decoupling circuit, a radio frequency trap and a radio frequency choke circuit, wherein the preamplifier circuit is arranged at the input end of the flexible coil unit, and the connection relationship of each specific component in the circuit is arranged as shown in FIG. Figure 5 As shown, this embodiment will not be described in detail. And each non-flexible coil unit is tuned to 123.3 MHz and matched to 50 ohms, which minimizes the impedance of the preamplifier noise coefficient, that is, low input impedance.

[0034] At the same time, a parallel resonant active detuning circuit (active detuning) with a high-power PIN diode is designed in the non-flexible coil unit circuit and placed at the input end before the amplifier for active detuning protection, so that when the high-power RF pulse is excited, the receiving array does not work, and when the RF pulse stops exciting, the receiving array starts working. The detuning protection circuit can further ensure the safety of the preamplifier.

[0035] like Figure 6 As shown, the circuit part of the flexible (or semi-flexible) coil unit in this embodiment includes but is not limited to a flexible high-impedance coaxial line (in the upper part of the figure) and a preamplifier circuit. The preamplifier circuit is provided at the input end of the flexible coil unit. The connection relationship of the remaining components in the circuit is as shown in FIG. Figure 6 The circuit design of the flexible coil unit can ensure that the fluctuation range of electrical parameters such as resonance, matching, decoupling and other performances is small under the premise of variable size, thereby ensuring that the electrical performance of the coil unit remains unchanged when the coil is bent, having high robustness and ensuring imaging stability.

[0036] Among them, the design method of using coaxial line instead of traditional copper sheet can make use of the high impedance characteristics of coaxial line to realize the high energy storage (high Q factor) design of coil electrical unit, and its shielding effect can effectively prevent electromagnetic interference and radio frequency interference, ensure the accuracy of signal transmission, and reduce radio frequency transmission loss. At the same time, the flexibility of the selected coaxial line provides better flexibility and bendability of the coil electrical unit, and the coil position can be adjusted within a suitable range according to the size of the head circumference or the size of the device housing to better fit the human body, so as to obtain a higher image signal-to-noise ratio.

[0037] The preamplifier in the flexible coil unit circuit is placed directly at the input of each coil unit, and the side components are connected to their respective preamplifiers located in the rear section of the equipment (such as MRI) housing through 10cm flexible coaxial cables. Each multi-conductor cable is wound into a large choke before leaving the housing. The common mode current on the ground shield of the coaxial cable is placed, and three cable traps are used at the same time to enhance the common mode current suppression.

[0038] In addition, this embodiment comprehensively considers factors such as matching the brain area and reserving space to accommodate support structures and fillers, and designs the accommodating inner diameter size to be 17.5mm*17.5mm*17.5mm. Except for the flexible coil unit, all coil units are attached to the surface of the inner shell printed by 3D machinery.

[0039] like Figure 7-9 As shown, this embodiment evaluates the performance of the semi-flexible RF receiving array control system by evaluating the image signal-to-noise ratio, noise level, noise correlation matrix and geometric acceleration factor, and compares its performance with the commercial coil used for adult imaging in the hospital. It is confirmed that the semi-flexible magnetic resonance RF receiving array system has a better noise matrix, lower noise, and a better image signal-to-noise ratio.

[0040] In summary, this embodiment designs a semi-flexible radio frequency receiving array control system for infant magnetic resonance imaging, which is characterized by a large number of coil array units, a high distribution density of coil units, and supports 2 times imaging acceleration in the left-right direction, the up-down direction, and the front-back direction. The rigid-flexible electrical unit design ensures the flexibility and large bending degree of the array unit, and can fit closely to the imaging area, thereby improving the infant imaging signal-to-noise ratio and image quality. Overlapping decoupling is used between adjacent channels, and inductive decoupling is used between non-adjacent channels to reduce electromagnetic coupling between channels, so that the array system has a lower noise coefficient and reduces the loss and noise of magnetic resonance signals.

[0041] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A radio frequency coil control system, characterized in that: It includes a head-top antenna module, a head-circumference antenna module and a headrest antenna module. The head-top antenna module includes at least 7 non-flexible coil units, the head-circumference antenna module includes at least 7 flexible coil units, and the headrest antenna module includes at least 18 non-flexible coil units.

2. A radio frequency coil control system as claimed in claim 2, characterized in that: The antenna units in the overhead antenna module and the antenna units in the headrest antenna module are arranged in a circular structure, and the flexible antenna units in the head circumference antenna module are arranged linearly.

3. A radio frequency coil control system according to claim 1 or 2, characterized in that: The non-flexible coil unit includes a resonant circuit, a matching circuit, an active detuning circuit, a passive detuning circuit, a preamplifier protection circuit, a preamplifier decoupling circuit, a radio frequency trap and a radio frequency choke circuit.

4. A radio frequency coil control system as claimed in claim 3, characterized in that: Each of the non-flexible coil units is tuned to 123.3 MHz and matched to 50 ohms.

5. The radio frequency coil control system according to claim 3, characterized in that: The active detuning circuit includes a high-power PIN diode and is arranged at an input end before the preamplifier protection circuit.

6. A radio frequency coil control system according to claim 1 or 2, characterized in that: The flexible coil unit comprises a flexible high-impedance coaxial line and a preamplifier circuit, and the preamplifier circuit is arranged at the input end of the flexible coil unit.

7. A radio frequency coil control system according to claim 1 or 2, characterized in that: Each of the non-flexible coil units and the flexible coil unit is arranged as a whole to form a spherical structure.

8. A radio frequency coil control system according to claim 1 or 2, characterized in that: The non-flexible coil unit includes a rectangular loop formed by copper skin.

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