Method for improving imaging resolution of electrical impedance tomography

• US 9,962,105 B2
• Filed: 12/28/2012
• Issued: 05/08/2018
• Est. Priority Date: 12/30/2011
• Status: Active Grant

• Current Assignee: National Chiao Tung University (Government of The Republic of China)
• Original Assignee: National Chiao Tung University (Government of The Republic of China)
• Inventors: Choi, Charles Tak Ming, Sun, Shu-Hai
• Primary Examiner(s): Stoklosa, Joseph
• Assistant Examiner(s): ANTISKAY, BRIAN MICHAEL
• Application Number:
  US13/729,811
• Publication Number:
  US 20130172718A1
• Time in Patent Office: 1,957 Days
• Field of Search: 600533, 600547
• CPC Class Codes: A61B 5/0536 Impedance imaging, e.g. by tomography
• CPC Class Codes: A61B 5/12 Audiometering
• CPC Class Codes: A61B 5/4064 Evaluating the brain A61B5/031, A61B5/369, A61B5/14553 take precedence
• CPC Class Codes: A61B 5/407 Evaluating the spinal cord A61B5/4896 takes precedence
• CPC Class Codes: A61B 5/6814 Head
• CPC Class Codes: A61B 5/6822 Neck
• CPC Class Codes: A61B 5/6823 Trunk, e.g., chest, back, abdomen, hip
• CPC Class Codes: A61B 5/6868 Brain
• CPC Class Codes: A61B 5/7225 Details of analog processing, e.g. isolation amplifier, gain or sensitivity adjustment, filtering, baseline or drift compensation A61B5/30, A61B5/316 take precedence; transformers for specific applications H01F38/00; amplifiers H03F
• CPC Class Codes: A61B 5/7278 Artificial waveform generation or derivation, e.g. synthesising signals from measured signals A61B5/327 takes precedence

Abstract

The present disclosure provides a method for improving imaging resolution of electrical impedance tomography (EIT). More specifically, the present disclosure forms virtual electrode(s) using an electric current steering technique, which is used to improve imaging resolution of an EIT system without physically increasing a number of conducting electrodes. The EIT system of the present disclosure may includes a plurality of conducting electrodes, at least one signal generator, at least one signal receiver and at least one electric current steering device. In other words, the present disclosure applies both the electric current steering technique and the virtual electrode technique to EIT. Consequently, imaging resolution of EIT can be improved without physically increasing the number of conducting electrodes.

Claims

1. A method for improving imaging resolution of electrical impedance tomography (EIT) using a plurality of conducting electrodes surrounding or inside a tissue structure, comprising the steps of:

(1) inputting an electric current, by an electric current source, into the tissue structure through at least two of the plurality of conducting electrodes, and outputting the electric current from at least an other one of the plurality of conducting electrodes;

(2) adjusting an electric current ratio of the inputted electric current according to an electric current steering device connected to the electric current source to form a virtual electrode between the at least two of the plurality of conducting electrodes, wherein the virtual electrode is located between the at least two of the plurality of conducting electrodes corresponding to the electric current ratio for inputting the electric current;

(3) measuring an electric potential using the at least two of the plurality of conducting electrodes, except these conducting electrodes for inputting and outputting the electric current, to obtain electric current and electric potential distributions corresponding to the plurality of conducting electrodes and the virtual electrode in the tissue structure; and

(4) performing an image conversion processing according to the electric current and electric potential distributions to profile an image for a specific region in the tissue structure.

2. The method of claim 1, wherein the electric current ratio is between 0%-100%.

3. The method of claim 1, wherein step (1) is performed by a signal generator, step (2) is performed by the electric current steering device connected with the signal generator, step (3) is performed by a signal receiver connected with the signal generator, and in step (4), the image conversion processing is performed by mathematical computing software and model parameters matching.

4. The method of claim 1, wherein the plurality of conducting electrodes are microelectrodes which are formed into an electrode array.

5. The method of claim 1, wherein the tissue structure is a brain, cochlea, spinal cord, a neck region or a chest region.

16. The method of claim 1, wherein a relation between the electric current ratio and the electric current is expressed as α

I;

(1−

α

)I, wherein I is the electric current and α

is the electric current ratio for inputting the electric current, and wherein 0≤

α

≤

1.

17. The method of claim 1, wherein a relation between the electric current ratio and the electric current is expressed as α

I;

β

I;

(1−

α

−

β

)I, wherein I is the electric current, α and

β

are the electric current ratios for inputting the electric current, and wherein 0≤

α

≤

1 and 0≤

β

≤

1.

6. A method for improving imaging resolution of electrical impedance tomography (EIT) using a plurality of conducting electrodes surrounding or inside a tissue structure, comprising the steps of:

(1) inputting an electric current, by an electric current source, into the tissue structure through at least one of the plurality of conducting electrodes, and outputting the electric current from at least other two of the plurality of conducting electrodes;

(2) adjusting an electric current ratio of the outputted electric current according to an electric current steering device connected to the electric current source to form a virtual electrode between the at least other two of the plurality of conducting electrodes, wherein the virtual electrode is located between the at least other two of the plurality of conducting electrodes corresponding to the electric current ratio for outputting the electric current;

(3) measuring an electric potential using the at least two of the plurality of conducting electrodes, except these conducting electrodes for inputting and outputting the electric current, to obtain electric current and electric potential distributions corresponding to the plurality of conducting electrodes and the virtual electrode in the tissue structure; and

(4) performing an image conversion processing according to the electric current and electric potential distributions to profile an image of a specific region in the tissue structure.

7. The method of claim 6, wherein the electric current ratio is between 0%-100%.

8. The method of claim 6, wherein step (1) is performed by a signal generator, step (2) is performed by the electric current steering device connected with the signal generator, step (3) is performed by a signal receiver connected with the signal generator, and in step (4), the image conversion processing is performed by mathematical computing software and model parameters matching.

9. The method of claim 6, wherein the plurality of conducting electrodes are microelectrodes which are formed into an electrode array.

10. The method of claim 6, wherein the tissue structure is a brain, cochlea, spinal cord, a neck region or a chest region.

18. The method of claim 6, wherein a relation between the electric current ratio and the electric current is expressed as α

I;

(1−

α

)I, wherein I is the electric current and a is the electric current ratio for outputting the electric current, and wherein 0≤

α

≤

1.

19. The method of claim 6, wherein a relation between the electric current ratio and the electric current is expressed as α

I;

β

I;

(1−

α

−

β

)I, wherein I is the electric current, α and

β

are the electric current ratios for outputting the electric current, and wherein 0≤

α

≤

1 and 0≤

β

≤

1.

11. A method for improving imaging resolution of electrical impedance tomography (EIT) using a plurality of conducting electrodes surrounding or inside a tissue structure, comprising the steps of:

(1) inputting an electric current, by an electric current source, into the tissue structure through at least two of the plurality of conducting electrodes, and outputting the electric current from at least other two of the conducting electrodes;

(2) adjusting at least two electric current ratios of the inputted and outputted electric currents according to an electric current steering device connected to the electric current source to form at least two virtual electrodes between the at least two of the plurality of conducting electrodes, wherein the virtual electrodes are located between the at least two of the plurality of conducting electrodes corresponding to the electric current ratio for inputting the electric current and between the at least other two of the conducting electrodes for outputting the electric current;

(3) measuring an electric potential using the at least two of the plurality of conducting electrodes, except these conducting electrodes for inputting and outputting the electric current, to obtain electric current and electric potential distributions corresponding to the plurality of conducting electrodes and the virtual electrodes in the tissue structure; and

(4) performing an image conversion processing according to the electric current and electric potential distributions to profile an image of a specific region in the tissue structure.

12. The method of claim 11, wherein the electric current ratios are between 0%-100%.

13. The method of claim 11, wherein step (1) is performed by a signal generator, step (2) is performed by the electric current steering device connected with the signal generator, step (3) is performed by a signal receiver connected with the signal generator, and in step (4), the image conversion processing is performed by mathematical computing software and parameter model matching.

14. The method of claim 11, wherein the plurality of conducting electrodes are microelectrodes which are formed into an electrode array.

15. The method of claim 11, wherein the tissue structure is a brain, cochlea, spinal cord, a neck region or a chest region.

20. The method of claim 11, wherein relations between the electric current ratio and the electric current are expressed as α

I;

(1−

α

)I and β

I;

(1−

β

)I, wherein I is the electric current, α

is the electric current ratio for inputting the electric current and β

is the electric current ratio for outputting the electric current, and wherein 0≤

α

≤

1 and 0≤

β

≤

1.