Spatial measurement of EEG electrodes

• US 5,817,029 A
• Filed: 06/26/1997
• Issued: 10/06/1998
• Est. Priority Date: 06/26/1997
• Status: Expired due to Fees

• Current Assignee: SAM Technology, Inc.
• Original Assignee: SAM Technology, Inc.
• Inventors: Le, Jian, Gevins, Alan S.
• Primary Examiner(s): Hindenburg, Max
• Assistant Examiner(s): MARMOR II, CHARLES ALAN
• Application Number:
  US08/883,022
• Time in Patent Office: 467 Days
• Field of Search: 600/544, 600/545, 600/383, 600/595
• US Class Current: 600/544
• CPC Class Codes: A61B 5/291 for electroencephalography [EEG]

Abstract

A method which is accurate and yet relatively simple, rapid and inexpensive for estimating 3-D coordinates of EEG (electroencephalograph) electrode positions on the head. The electrode positions of any number of scalp electrodes placed according to the standard 10/10 electrode position system are computed by a computer system based on 14 manually measured inter-electrode distances and 9 electrode-to-skull landmark straight-line distances. The measurements are made manually using digital calipers.

Claims

1. A method of locating the 3-D (3-dimensional) positions of a set of 32 or more EEG (electroencephalograph) electrodes removably positioned on the head of a subject comprising:

(a) placing the electrodes on the head with eleven of the electrodes positioned in a 10/10 placement;

(b) placing the other electrodes on the head in predetermined spaced relationship between the eleven electrodes of (a);

(c) measuring the distances between the eleven electrodes of (a);

(d) entering the measured distances of (c) into a computer system and based thereon computing estimates of the 3-D positions of the other electrodes of the set of electrodes.

2. A method as in claim 1 wherein the set consists of 64 EEG electrodes.

3. A method as in claim 1 wherein the other electrodes of (b) are placed at equal distances from the eleven electrodes or from each other.

4. A method as in claim 1 wherein the measurements are made by operation of digital calipers.

5. A method as in claim 1 wherein the computation of (d) is based upon imaginary curves formed in a plurality of planes.

6. A method as in claim 5 wherein the curves are ellipsoids.

7. A method as in claim 5 wherein at least three of the planes are spaced apart.

8. A method as in claim 1 wherein in (c) eight inter-electrode distances are measured to determine three coronal planes and two horizontal planes, and six inter-electrode distances are measured to determine the distances between the five planes.

9. A method as in claim 8 and, in the computer system, generating perturbed ellipsoidal curves from the 14 inter-electrode distances and computing the estimates of the 3-D positions of the other electrodes by subdividing the ellipsoidal curves and extrapolating.

10. A method as in claim 8 and also performing a plurality of position measurements to determine a plurality of fiducial landmarks on the subject'"'"'s head and distances from the fiducial landmarks to at least some of the eleven electrodes.

11. A method as in claim 10 wherein the fiducial landmarks comprise the nasion, left and right preauricular notches.

12. A method as in claim 11 wherein the set of electrodes are positioned in a stretch cap on the subject'"'"'s head.

13. A method of locating the 3-D (3-dimensional) positions of a set of 32 or more EEG (electroencephalograph) electrodes removably positioned on the head of a subject comprising:

(a) placing the electrodes on the head with at least five of the electrodes positioned in a 10/10 placement;

(b) placing the other electrodes on the head in a predetermined spaced relationship between the five electrodes of (a);

(c) measuring the distances between the five electrodes of (a);

(d) entering the measured distances of (c) into a computer system and based thereon computing estimates of the 3-D positions of the other electrodes of the set of electrodes.

14. A method as in claim 13 wherein the set consists of 64 EEG electrodes.

15. A method as in claim 13 wherein the other electrodes of (b) are placed at equal distances from the five electrodes or from each other.

16. A method as in claim 13 wherein the measurements are made by operation of digital calipers.

17. A method as in claim 16 wherein the curves are ellipsoids.

18. A method as in claim 17 and, in the computer system, generating ellipsoidal curves from the measured inter-electrode distances and computing the estimates of the 3-D positions of the other electrodes by subdividing the ellipsoidal curves and extrapolating.

19. A method as in claim 13 and also performing a plurality of position measurements to determine a plurality of fiducial landmarks on the subject'"'"'s head and distances from the fiducial landmarks to at least some of the five electrodes.

20. A method as in claim 13 wherein the fiducial landmarks comprise the nasion, left and right preauricular notches.

21. A method as in claim 13 wherein the set of electrodes are positioned in a stretch cap on the subject'"'"'s head.