Magnetic resonance imaging scanner with coil serving as inductor of power amplifier

• US 10,641,847 B2
• Filed: 11/14/2017
• Issued: 05/05/2020
• Est. Priority Date: 05/14/2015
• Status: Active Grant

• Current Assignee: Bilkent University
• Original Assignee: Bilkent University
• Inventors: Atalar, Ergin, Poni, Redi
• Primary Examiner(s): Hoque, Farhana A
• Application Number:
  US15/812,421
• Publication Number:
  US 20180081003A1
• Time in Patent Office: 903 Days
• Field of Search: 324300-322, 600407-435, 382128-131
• CPC Class Codes: A61B 5/01 Measuring temperature of body parts ; Diagnostic temperature sensing, e.g. for malignant or inflamed tissue clinical contact thermometers G01K13/20
• CPC Class Codes: A61B 5/055 involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
• CPC Class Codes: A61B 5/0816 Measuring devices for examining respiratory frequency measuring frequency of electric signals G01R23/00
• CPC Class Codes: A61B 5/318 Heart-related electrical modalities, e.g. electrocardiography [ECG]
• CPC Class Codes: G01R 33/3607 RF waveform generators, e.g. frequency generators, amplitude-, frequency- or phase modulators or shifters, pulse programmers, digital to analog converters for the RF signal, means for filtering or attenuating of the RF signal
• CPC Class Codes: G01R 33/3614 RF power amplifiers

Abstract

According to an embodiment of the present disclosure, disclosed is an apparatus for generating a radio frequency (RF) pulse in a magnetic resonance imaging (MRI) scanner. The apparatus for generating a radio frequency (RF) pulse in a magnetic resonance imaging scanner includes: a control module controlling a power amplifier and a signal generator; the signal generator configured to generate a signal of a predetermined waveform based on control by the control module and supply the generated signal of the predetermined waveform to the power amplifier in electromagnetic connection therewith; a power amplifier amplifying the signal supplied from the signal generator based on the control by control module and outputting the amplified signal to a coil; and the coil serving as an inductor of the power amplifier and transferring the amplified signal to the object so that an object is excited.

Claims

1. An apparatus for generating a radio frequency (RF) pulse in a magnetic resonance imaging (MRI) scanner, the apparatus comprising:

a plurality of control modules controlling a plurality of Class E power amplifiers,

wherein based on control by each control module of the plurality of control modules each amplifier of the plurality of amplifiers is configured to receive a predetermined supply signal and amplify the signal, such that the signal on each amplifier is independent; and

a plurality of coils, each amplifier being electrically connected to a coil of the plurality of coils and each amplifier outputting the amplified signal to

the electrically connected coil thereto,

wherein each output amplified signal is configured such that its waveform, period, and/or amplitude to the coil is independently controlled, and

wherein each coil of the plurality of coils serves as an inductor for its electrically connected power amplifier and further transfers the amplified signal to the object so that the object is excited.

2. The apparatus of claim 1, wherein each power amplifier comprises:

a choke inductance component receiving power supplied from a signal generator,

a switching transistor controlled by each control module, and

one or more capacitors capable of storing electric charges.

3. The apparatus of claim 2, wherein the signal generator supplies a normal square waveform to at least one of the power amplifiers.

4. The apparatus of claim 2, wherein each control module is configured based on an FPGA, generates a binary bitstream, and turns on or off the switching transistor of each power amplifier.

5. The apparatus of claim 4, wherein a period of a bit of each of binary bitstream signals generated by each control module is a half of a switching period of each power amplifier.

6. The apparatus of claim 4, wherein each control module determines parameters of a circuit by pre-scanning the circuit of each power amplifier and supplies the binary bitstream signal to each power amplifier based on the determined parameters.

7. The apparatus of claim 2, further comprising a converter electrically connecting each coil and control module so as to transfer the signal, wherein each control module controls each power amplifier and signal generator based on a feedback signal transferred through the converter.

8. The magnetic resonance imaging scanner of claim 2, wherein the choke inductance component is configured by a choke inductor.

9. The magnetic resonance imaging scanner of claim 8, wherein the transmission line is selected from the group consisting of a coaxial cable, a microstrip, and a strip line.

10. The apparatus of claim 2, wherein the apparatus is characterized by an impedance for the choke inductance component is such that the impedance is the same for both a length of transmission line and for a choke inductor.

11. The apparatus of claim 2, wherein the choke inductance component is configured by a transmission line.

12. The apparatus of claim 1, wherein each power amplifier is characterized by a sum of coil resistance and object resistance.

13. The apparatus of claim 1, wherein the coil is a capacitor and an LC leg.

14. A magnetic resonance imaging scanner, comprising:

an RF pulse generating apparatus,

wherein the RF pulse generating apparatus comprises;

a plurality of control modules controlling a plurality of Class E power amplifiers,

wherein based on control by each control module of the plurality of control modules each amplifier of the plurality of amplifiers is configured to receive a predetermined supply signal and amplify the signal, such that the signal on each amplifier is independent; and

a plurality of coils, each amplifier being electrically connected to a coil of the plurality of coils and each amplifier outputting the amplified signal to

the electrically connected coil thereto,

wherein each output amplified signal is configured such that its waveform, period, and/or amplitude to the coil is independently controlled, and

wherein each coil of the plurality of coils serves as an inductor for its electrically connected power amplifier and further transfers the amplified signal to the object so that the object is excited.

15. The magnetic resonance imaging scanner of claim 14, wherein each power amplifier comprises:

a choke inductance component receiving power supplied from a signal generator,

a switching transistor controlled by the control module, and

one or more capacitors capable of storing electric charges.

16. The magnetic resonance imaging scanner of claim 15, wherein the choke inductance component is configured by a transmission line.

17. The magnetic resonance imaging scanner of claim 15, wherein the choke inductance component is configured by a choke inductor.

18. The magnetic resonance imaging scanner of claim 17, wherein the transmission line is selected from the group consisting of a coaxial cable, a microstrip, and a strip line.

19. The magnetic resonance imaging scanner of claim 15, wherein the apparatus is characterized by an impedance for the choke inductance component is such that the impedance is the same for both a length of the transmission line and for a choke inductor.