Non-linear projections of 3-d medical imaging data

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.

What is claimed is: 
     
         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;   d. generating three dimensional volume image data of the eye from the combined light;   e. identifying a first surface within the image data;   f. 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;   g. 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;   h. determining a smooth reference surface using the locations of the set of identified image points;   i. generating an image based on the smooth reference surface; and   j. storing or displaying the image.   
     
     
         2 . A method as recited in  claim 1 , wherein the smooth reference surface is determined by fitting. 
     
     
         3 . A method as recited in  claim 1 , further comprising using the intensity of image pixels within the volume to determine intensities at the locations on the smooth surface. 
     
     
         4 . A method as recited in  claim 1 , wherein the image is generated by integrating a certain margin above and below the smooth reference surface. 
     
     
         5 . 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;   d. generating three dimensional volume image data of the eye from the combined light;   e. identifying a first surface within the image data;   f. 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;   g. 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;   h. generating an image based on information associated with the selected set of image points; and   i. displaying the image.   
     
     
         6 . A method as recited in  claim 5 , wherein the subvolume contains the outer nuclear layer (ONL) of the eye, wherein the common intensity attribute corresponds to the minimum intensity of the associated ray projections, and further comprising identifying regions of retinal disruptions based on the minimum intensity. 
     
     
         7 . A method as recited in  claim 6 , wherein the minimum intensity is used to identify areas at risk of future pathology. 
     
     
         8 . A method as recited in  claim 5 , wherein the image generation is based on location information associated with each of the selected set of image points within the associated ray projection and wherein the generated image is a height map of the maximum intensity locations relative to a reference surface. 
     
     
         9 . A method as recited in  claim 5 , wherein the generated image is a height map of the common intensity attribute locations and the height is encoded by color or brightness. 
     
     
         10 . A method as recited in  claim 5 , wherein one or more of the ray projections are along axes different from the propagation axis of the beam.