U.3.2.5 Transverse Imaging
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#### U.3.2.5 Transverse Imaging

While the majority of ophthalmic tomography imaging consists of sets of longitudinal images (also known as B scans or line scans), transverse images (also known as coronal or "en face" images) can also provide useful information in determining the full extent of the volume affected by pathology.

Longitudinal images are oriented in a manner that is perpendicular to the structure being examined, while transverse images are oriented in an "en face" or near parallel fashion through the structure being examined.

Transverse images can be obtained from a directly as a single scan (as shown in Figures U.3-8 and U.3-9) or they can also be reconstructed from a 3D data set (as shown in Figures U.3-10 and U.3-11). A sequence of transverse images can also be combined to form a 3D data set.

Figure U.3-8. Transverse OCT Image

Figure U.3-9. Correlation between a Transverse OCT Image and a Reference Image Obtained Simultaneously

Figures U.3-8 through U.3-11 are all images of the same pathology in the same eye, but the two different orientations provide complementary information about the size and shape of the pathology being examined. For example, when examining macular holes, determining the amount of surrounding cystic formation is important aid in the following treatment. Determining the extent of such cystic formation is much more easily ascertained using transverse images rather than longitudinal images. Transverse images are also very useful in locating micro-pathologies such as covered macular holes, which may be overlooked using conventional longitudinal imaging.

Figure U.3-10. Correspondence between Reconstructed Transverse and Longitudinal OCT Images

Figure U.3-11. Reconstructed Transverse and Side Longitudinal Images

In Figure U.3-10, the blue green and pink lines show the correspondence of the three images. In Figure U.3-11, the Transverse image is highlighted in yellow.

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