New OCT tool to study how diseases like dementia, Alzheimer’s, and brain tumors change brain tissue over time. “In the brain, the imaging depth is almost doubled,” said Martin Leahy of the National University of Ireland, Galway. “The authors demonstrate for the first time an application in which this capability opens up a whole new window into the live intact hippocampus, for discovery in brain research.”
From the experimental findings, the authors envision that this new optical coherence tomography (OCT) approach to brain study may enable examination of acute and chronic morphological or functional vascular changes in the deep brain, which has been rarely attempted before in the OCT community.
Choi and Wang used swept-source OCT (SS-OCT) powered by a vertical-cavity surface-emitting laser (VCSEL). In “Swept-source OCT powered by a 1.3 μm vertical cavity surface emitting laser enables 2.3 mm-deep brain imaging in mice in vivo,” they describe how this technique could allow monitoring of morphological changes by disease and aging on the brain.
Refining a VCSEL SS-OCT system may make it possible to do things that have been barely attempted, such as full-length imaging of a human eye from cornea to retina. An OCT camera can instantly deliver cross-section images of layers of tissue without invasive surgery or ionizing radiation.
Widely applied over the past 2 decades in clinical ophthalmology, it has been adapted for brain imaging in small animal models. Scientists used OCT imaging to study the structure, neural activity, and blood flow in the cerebral cortex of live mice. Its application in neuroscience has been limited, however, because conventional OCT technology hasn’t been able to image more than 1 millimeter below the surface of biological tissue.
OCT images are based on reflected light directly reflected at sub-surface. At depths greater than 1 mm, the proportion of light (ballistic photons) that escapes without scattering became too small to be detected, so conventional OCT systems have not been able to image deeper tissues such as the hippocampus, where many pathologies originate. Swept-source OCT powered by VCSELs dramatically improved usable imaging range because of its improved system sensitivity, extending the imaging range to >2 millimeters. http://spie.org/x115785.xml
(a) Representative OCT image visualizing morphological details of the cerebral cortex and subsequent brain compartments. (b) OCT brain anatomy showing good correlation with photomicrograph of a Nissl-stained histology section of the same strain mouse brain. Credit: Reprinted with a public courtesy from Allen Institute for Brain Science.
Recent Comments