Low-coherence imaging of cerebral structures in vivo

We present the results of detailed optical coherence tomographic (OCT) observations of both normal and abnormal rat neocortices obtained in vivo. A compact fast-scanning OCT device employing simultaneously two superluminescent sources of radiation at different wavelengths (0.83 and 1.28 micron) has recorded three dimensional images and performed two-color comparative analysis of the tomograms. We are able to obtain image information at 2.5 mm depths, enabling imaging through the entire rat cerebral cortex. Structures inside and at the surface of the brain have been optically detected, including the dura matter, blood vessels, and the hippocampal/cortical boundary. From these, we have recorded and stored the first OCT album of the cortex. Subsequent histologic analysis shows a good correlation with the OCT tomograms, particularly within the cortical surface layers and the boundary between gray and white matter. We are also able to detect differences between normal and abnormal cerebral structure using OCT.