Method and system for displaying confidence intervals for source reconstruction
The present invention involves the creation of an appropriate model and the use of that model to generate a best fit dipole represented by a vector (x, y, z). Once the best fit dipole is generated, a best fit field distribution and a field distribution of a modified dipole is created. Using a difference between the field distributions, a Singular Value Decomposition is used to compute the main axes of the confidence ellipsoids.
1. A method comprising:
modeling neural activity as single equivalent current dipoles (ECD's);
calculating best fit dipole coordinates for each dipole;
calculating a field distribution based on the best fit dipole coordinates;
modifying the best fit dipole coordinates to create modified dipole coordinates;
calculating a modified field distribution based on the modified dipole coordinates;
computing a difference between the field distribution and the modified field distribution;
computing a confidence interval for each dipole based on the difference between the field distribution and the modified field distribution; and
displaying the confidence interval in an overlay on a three-dimensional image obtained through the use of either magnetic resonance imaging (MRI) or computerized tomography (CT).
2. The method of claim 1 , wherein the step of computing a confidence interval includes computing an error ellipsoid using a Singular Value Decomposition.
3. The method of claim 1 , wherein the step of modeling includes assuming the geometric and conductive properties of cardiac or cortical tissue.
4. The method of claim 1 , wherein the step of computing a confidence interval includes the step of performing a signal to noise ratio analysis.
5. The method of claim 1 , and further comprising defining a Cartesian coordinate system.
6. An apparatus comprising:
a detector;
a processor adapted to receive data from the detector, and using the processor to:
calculate best fit dipole coordinates for each dipole;
calculate a field distribution based on the best fit dipole coordinates;
modify the best fit dipole coordinates to create modified dipole coordinates;
calculate a modified field distribution based on the modified dipole coordinates;
compute a difference between the field distribution and the modified field distribution; and compute a confidence interval for each dipole based on the difference between the field distribution and the modified field distribution;
an imaging source in communication with the processor; and
a display in communication with the processor and adapted to display the confidence interval in three dimensions relative to a three-dimensional anatomical image, wherein the three-dimensional anatomical image is obtained through the use of the imaging source.
7. The apparatus of claim 6 , wherein the imaging source is an MRI unit.
8. The apparatus of claim 6 , wherein the imaging source is a CT unit.
9. The apparatus of claim 6 , wherein the detector comprises electroencephalogram sensors.
10. The apparatus of claim 6 , wherein the detector comprises magnetoencephalogram sensors.
11. A method comprising:
measuring a plurality of electrical or magnetic signals;
calculating best fit dipole coordinates for each signal;
calculating a field distribution based on the best fit dipole coordinates;
modifying the best fit dipole coordinates to create modified dipole coordinates;
calculating a modified field distribution based on the modified dipole coordinates;
computing a difference between the field distribution and the modified field distribution;
computing a confidence interval for the best fit dipole coordinates for each signal based on the difference between the field distribution and the modified field distribution; and
displaying the confidence interval on a three-dimensional anatomical map, wherein the confidence interval is displayed in its anatomical position in three dimensions.
12. The method of claim 11 , wherein the step of computing a confidence interval includes computing confidence ellipsoid axes from an estimated noise level and different field strengths.
13. The method of claim 11 , wherein the step of displaying includes the step of receiving a digital image.
14. The method of claim 11 , wherein the step of computing a confidence interval includes the step of computing a confidence volume.
15. The apparatus of claim 7 , wherein the detector comprises electroencephalogram sensors.
16. The apparatus of claim 8 , wherein the detector comprises electroencephalogram sensors.
17. The method of claim 5 , wherein the Cartesian coordinate system is anchored on at least three fiducial points on a patient's head.
18. The method of claim 11 , further comprising defining a Cartesian coordinate system anchored on at least three fiducial points on a patient's head.