Optical coherence tomography visualizes neurons in human entorhinal cortex

Abstract

The cytoarchitecture of the human brain is of great interest in diverse fields: neuroanatomy, neurology, neuroscience, and neuropathology. Traditional histology is a method that has been historically used to assess cell and fiber content in the ex vivo human brain. However, this technique suffers from significant distortions. We used a previously demonstrated optical coherence microscopy technique to image individual neurons in several square millimeters of en-face tissue blocks from layer II of the human entorhinal cortex, over 50 µm in depth. The same slices were then sectioned and stained for Nissl substance. We registered the optical coherence tomography (OCT) images with the corresponding Nissl stained slices using a nonlinear transformation. The neurons were then segmented in both images and we quantified the overlap. We show that OCT images contain information about neurons that is comparable to what can be obtained from Nissl staining, and thus can be used to assess the cytoarchitecture of the ex vivo human brain with minimal distortion. With the future integration of a vibratome into the OCT imaging rig, this technique can be scaled up to obtain undistorted volumetric data of centimeter cube tissue blocks in the near term, and entire human hemispheres in the future.

Visualizing and mapping the cerebellum with serial optical coherence scanner

“…7 In recent years, OCT for brain imaging has drawn attention because of the increasing research interest in brain microstructure and circuitry. In addition to the visualizations of cortical layers and neurons, [8][9][10][11] OCT has been used to study pathological changes in brain conditions such as brain tumors, [12][13][14] edema, 15 and seizures. 16 OCT has also been shown to separate different layers in the cerebellar cortex 17,18 and Purkinje cell bodies 13 in the cerebellum.…”

Full-Field Optical Coherence Tomography as a Diagnosis Tool: Recent Progress with Multimodal Imaging

“…The main advantage of OCT is its virtual sectioning ability, enabling imaging at a few hundred microns below the tissue surface, hence reasonably far from the sectioned surface no matter which section is required [58]. To completely remove slicing artifacts and reach large depths, OCT systems have successfully been coupled to a vibratome, in a procedure where an entire volume is imaged before a physical slice smaller than the imaged volume is performed [59].…”

“…It is usually preferred to perform the OCT imaging before any sample modification, as OCT signal alteration can occur after fixation, depending on the tissue content [62] (especially since fixatives often remove lipidic structures of the cells). Keeping this in mind, it is nevertheless possible to perform histology-like measurements in fixed tissues [58].…”

“…Scanning OCT has also been used successfully to perform histology-like measurements [58,[63][64][65], and to detect tumor regions [66,67] through changes in the collagen content [68], the tissue microangiogram and backscattering [69], or in the tissue fractal dimension [70]. However, we believe that the high resolution of FF-OCT can significantly improve the diagnostic abilities of OCT [8,17].…”

Design and Implementation Guidelines for a Modular Spectral-Domain Optical Coherence Tomography Scanner

“…Optical coherence tomography can visualize the detailed structure of different biological tissue samples [2] such as brain cytoarchitecture [3], large cellular structures (e.g., [4,5]), or retinal layers in the eye ( [6][7][8] to name a few) or functional retinal images (e.g., [9,10]). In addition, it can provide functional information by capturing the vascular morphology through optical coherence angiography (e.g., [11][12][13][14]) or by recording vascular blood velocity (e.g., [15][16][17][18]).…”