Non-linear projections of 3-D medical imaging data

• US 8,332,016 B2
• Filed: 08/04/2009
• Issued: 12/11/2012
• Est. Priority Date: 08/04/2009
• Status: Active Grant

• Current Assignee: Carl Zeiss Meditec Incorporated (Carl-Zeiss-Stiftung)
• Original Assignee: Carl Zeiss Meditec Incorporated (Carl-Zeiss-Stiftung)
• Inventors: Stetson, Paul F.
• Primary Examiner(s): Kish, James
• Assistant Examiner(s): Fisher, Michael N
• Application Number:
  US12/535,046
• Publication Number:
  US 20110034803A1
• Time in Patent Office: 1,225 Days
• Field of Search: 600/310, 600/356, 600/383, 600/400, 600/407, 356/4.01, 356/4.07, 356/5.04, 356/479, 356/489, 356/495, 356/497, 356/515
• US Class Current: 600/476
• CPC Class Codes: A61B 2560/0475 Special features of memory means, e.g. removable memory cards
• CPC Class Codes: A61B 3/0025 characterised by electronic signal processing, e.g. eye models
• CPC Class Codes: A61B 3/0041 characterised by display arrangements
• CPC Class Codes: A61B 3/102 for optical coherence tomography [OCT]
• CPC Class Codes: A61B 3/14 Arrangements specially adapted for eye photography apparatus or arrangements for taking photographs per se G03B
• CPC Class Codes: G06T 11/003 Reconstruction from projections, e.g. tomography
• CPC Class Codes: G06T 15/08 Volume rendering
• CPC Class Codes: G06T 2207/10101 Optical tomography; Optical coherence tomography [OCT]
• CPC Class Codes: G06T 2207/30041 Eye; Retina; Ophthalmic
• CPC Class Codes: G06T 7/0012 Biomedical image inspection
• CPC Class Codes: G06T 7/12 Edge-based segmentation

Abstract

The present invention improves projection displays of volume data. Using the Minimum Intensity Projection (MinIP), fluid filled regions or other regions of hyporeflective tissue are displayed. By limiting the projection to partial volumes within the volume, differences in the scattering intensity within specific regions are isolated. In this way, hyperreflectivity of weakly scattering tissue can be assessed.

Claims

1. A method of generating an image of an anatomical region within an eye, said eye being examined by an optical coherence tomography (OCT) system, said OCT system including a light source for generating a beam of light, a sample arm, a reference arm, and a detector for measuring light combined from the sample and reference arms, said method comprising the steps of:

a. scanning the beam of light over a region of the eye via the sample arm;

b. combining the light from the sample and reference arms;

c. measuring the combined light to generate three dimensional volume image data of the eye;

d. identifying a first surface within the image data;

e. identifying a subvolume of the image data, said subvolume having less than all the generated image data, said subvolume being identified based upon the identification of the first surface, said subvolume being either bounded by or including the first surface, said subvolume including the anatomical region;

f. selecting a set of image points within the subvolume, said image points being selected by evaluating a plurality of ray projections extending through the subvolume and identifying one image point in each projection, wherein each of the identified image points has a common intensity attribute;

g. generating an image based on information associated with the selected set of image points; and

h. storing or displaying the image.

2. A method as recited in claim 1, wherein the common intensity attribute corresponds to the minimum intensity of the associated ray projection.

3. A method as recited in claim 1, wherein the common intensity attribute corresponds to the maximum intensity of the associated ray projection.

4. A method as recited in claim 1, wherein the common intensity attribute corresponds to the median intensity of the associated ray projection.

5. A method as recited in claim 1, wherein the generated image is based directly on the intensity of each of the selected set of image points.

6. A method as recited in claim 1, wherein the image generation is based on location information associated with each of the selected set of image points within the associated ray projection.

7. A method as recited in claim 6, wherein the generated image is a height map of the minimum intensity locations relative to a reference surface.

8. A method as recited in claim 7, wherein the height map is displayed as a surface within a 3-D volume.

9. A method as recited in claim 1, further comprising the step of identifying a second surface within the volume image of the sample and wherein the subvolume is identified based on the first and second surfaces.

10. A method as recited in claim 1, further comprising the step of identifying a second surface based on the locations of the selected set of image points.

11. A method as recited in claim 10, wherein the second surface is a smooth surface fit to the selected set of image points.

12. A method as recited in claim 1, wherein the generated image includes at least one region of retinal disruption.

13. A method as recited in claim 1, wherein the data within the subvolume is smoothed prior to the selection of image points within the subvolume.

14. A method as recited in claim 1, wherein local intensity variations in the image volume are compensated for by applying a local normalization factor prior to display of the image.

15. A method as recited in claim 14, wherein the normalization factor is a function of the points within a ray projection from which the associated image point was selected.

16. An apparatus for obtaining an image of an eye comprising:

a. an optical coherence tomography (OCT) system, said system including a light source for generating a beam of light, a sample arm, a reference arm, a detector for measuring light combined from the sample and reference arms, and a scanner for scanning the light beam over the eye, said system generating a volume of intensity information; and

b. a processor for selecting a subvolume of intensity image information from the volume of intensity information, said subvolume having less than all the generated intensity information and thereafter generating a two dimensional image derived by identifying a single image point associated with each of a plurality of ray projections extending through the subvolume; and

c. one of a display or a memory, said display for displaying the image and said memory for storing the image.

17. An apparatus as recited in claim 16, wherein the image points associated with each of the ray projections have a common intensity attribute.

18. An apparatus as recited in claim 17, wherein the common intensity attribute is a minimum intensity.

19. A method of ophthalmic imaging comprising:

a. obtaining a volume image of the eye;

b. identifying a subvolume of image information within the volume image, said subvolume having less than all the obtained image information;

c. generating a set of two dimensional intensity projections within the subvolume, the intensity projections being derived by identifying a single image point associated with each of a plurality of ray projections extending through the subvolume;

d. selecting one of the set of intensity projections; and

e. storing or displaying the determined intensity projection.

20. A method of ophthalmic imaging comprising:

a. obtaining a volume image of the eye;

b. identifying a subvolume of image information, said subvolume having less than all the obtained image information;

c. casting a plurality of projection rays through the subvolume;

d. identifying a collection of locations along each projection ray, wherein the collection contains fewer locations than all of the locations of the projection ray within the subvolume;

e. determining an intensity value as a non-linear function of image intensity associated with the collection of locations for each ray;

f. generating an image of the determined intensity values; and

g. displaying the image.

21. A method of generating an image of an anatomical region within an eye, said eye being examined by an optical coherence tomography (OCT) system, said OCT system including a light source for generating a beam of light, a sample arm, a reference arm, and a detector for measuring light combined from the sample and reference arms, said method comprising the steps of:

a. scanning the beam of light over a region of the eye via the sample arm;

b. combining the light from the sample and reference arms;

c. measuring the combined light to generate three dimensional volume image data within the eye;

d. identifying a subvolume of data located between a pair of surfaces within the eye, said subvolume having less than all the generated image data;

e. selecting a set of image points within the subvolume, said image points being selected by evaluating a plurality of ray projections extending through the subvolume and identifying one image point in each projection, wherein each of the identified image points has a minimum intensity;

f. generating an image based on the selected set of image points; and

g. storing or displaying the image.