Optical coherence microscopy for deep tissue imaging of the cerebral cortex with intrinsic contrast

Abstract

Abstract:In vivo optical microscopic imaging techniques have recently emerged as important tools for the study of neurobiological development and pathophysiology. In particular, two-photon microscopy has proved to be a robust and highly flexible method for in vivo imaging in highly scattering tissue. However, two-photon imaging typically requires extrinsic dyes or contrast agents, and imaging depths are limited to a few hundred microns. Here we demonstrate Optical Coherence Microscopy (OCM) for in vivo imaging of neuronal cell bodies and cortical myelination up to depths of ~1.3 mm in the rat neocortex. Imaging does not require the administration of exogenous dyes or contrast agents, and is achieved through intrinsic scattering contrast and image processing alone. Furthermore, using OCM we demonstrate in vivo, quantitative measurements of optical properties (index of refraction and attenuation coefficient) in the cortex, and correlate these properties with laminar cellular architecture determined from the images. Lastly, we show that OCM enables direct visualization of cellular changes during cell depolarization and may therefore provide novel optical markers of cell viability.

Volumetric imaging and quantification of cytoarchitecture and myeloarchitecture with intrinsic scattering contrast

“…The sensitivity was approximately 100 dB. Further details of the system have been previously reported [7]. For imaging, the sample arm assembly was initially set so that the optical focus was just above the cortical surface.…”

“…Third-harmonic generation also visualizes neuronal cell bodies due to lack of structural phase matching [5]. Elastic backscattering techniques such as Optical Coherence Microscopy (OCM) and confocal reflectance microscopy provide contrast comparable to third-harmonic generation in brain tissue, depicting both neuronal cell bodies and myelinated axons [6][7][8][9]. The birefringent properties of the myelin sheath can be interrogated with polarization-sensitive imaging to provide additional contrast [10].…”

Optical coherence tomography for precision brain imaging, neurosurgical guidance and minimally invasive theranostics

“…Some advanced technologies have been integrated into the OCT system for improving light penetration to enhance imaging depth in highly scattering brain tissue. Imaging depth of OCM is improved through intrinsic scattering contrast (41). This method does not require the addition of dyes or contrast agents.…”

“…Moreover, UHR OCT is a successfully translational diagnosis tool, since it is capable of discriminating healthy brain tissue and various neuro-pathologies. For imaging deep brain tissue in vivo, a forward scanning single mode fiber (φ125 μm) is used as detecting probe (40,41). Some advanced technologies have been integrated into the OCT system for improving light penetration to enhance imaging depth in highly scattering brain tissue.…”

Swept source optical coherence microscopy using a 1310 nm VCSEL light source

“…Breast, lung, thyroid, and head and neck cancers would benefit from an imaging modality that enables real time assessment of surgical specimens and could reduce the rates of second surgeries from positive or close surgical margins [7][8][9]. OCM also has a broad range of applications for research and biological microscopy, ranging from cellular level imaging of the cortex in small animals, to in vivo imaging of developmental biology specimens [10][11][12][13][14].…”