Establishing compatibility between two- and three-dimensional optical coherence tomography scans
Advances in optical coherence tomography (OCT) have prompted a transition from time domain OCT, providing 2D OCT images, to spectral domain OCT, which has a 3D imaging capability. Yet conventional technology offers little toward the goal of inter-device compatibility between extant 2D OCT images and newer 3D OCT images for the same or comparable subjects, as in the context of ongoing monitoring the quantitative status of a patient's eyes. The inventive methodology is particularly useful to identify the scan location of tissue in a 2D OCT image within the 3D OCT volumetric data, thereby allowing clinicians to image a patient via 3D OCT, based on available 2D OCT images, with minimal inter-device variation.
1. A method of establishing image registration between a two-dimensional optical coherence tomography (OCT) image and a three-dimensional optical coherence tomography image, comprising the steps of:
(A) obtaining, with a first type of OCT device, the two-dimensional image using a pre-defined scanning protocol such that the two-dimensional image includes a portion of an eye;
(B) obtaining, with a second type of OCT device different than the first type of OCT device, the three-dimensional image such that the three-dimensional image includes said portion; then,
(C) in the three-dimensional image, delineating a region of interest within said portion; then
(D) re-sampling said region of interest using said pre-defined scanning protocol to generate at least one two-dimensional re-sampled image; then,
(E) in each of said two-dimensional image and said re-sampled image, detecting at least one feature of interest common to both images; then
(F) correlating between said feature in said two-dimensional image and said re-sampled image, respectively, with respect to at least one similarity measure to identify a location on said feature in said two-dimensional image and said re-sampled image, respectively, wherein said location exhibits the highest value of said measure; and then
(G) establishing image registration between said re-sampled image and said two-dimensional image, based on spatial information about said location.
2. The method of claim 1 , wherein step (E) further comprises frequency domain image processing or spatial domain image processing, or a combination thereof.
3. The method of claim 1 , wherein step (F) further comprises multiplying a two-dimensional Gaussian probability density function with a cross-correlation map.
4. The method of claim 1 , wherein the step (F) further comprises correcting artifacts in said re-sampled image resulting from eye motion during step (B).
5. The method of claim 1 , wherein said similarity measure is a sum of absolute differences, cross-correlation, invariant moments, Euclidean distance, mutual information, or combinations thereof.
6. The method of claim 1 , wherein said spatial information is selected from the group consisting of X-Y coordinates, angle, scale, and combinations thereof.
7. The method of claim 1 , wherein the pre-defined scanning protocol involves scanning the portion in a circular pattern.
8. The method of claim 1 , wherein the second type of OCT device obtains the three-dimensional image using a second scanning protocol.
9. The method of claim 1 , wherein the second scanning protocol is different than the pre-defined scanning protocol.