The authors of this Optics Letters paper demonstrate imaging of subcortical structures in mice using optical coherence tomography at a wavelength of 1.7 μm. Unlike fluorescence microscopy, optical coherence tomography measures intrinsic backscattering and does not require any labeling. The use of a longer wavelength reduces scattering and potentially increases the imaging depth, but at the cost of decreasing the useful backscatter signal and increased water absorption. The authors resolve the argument over this trade-off by comparing tomograms of the same mouse brain imaged at various wavelengths. This clearly demonstrates the benefits of the longer wavelength at 1.7 μm in terms of imaging depth.
In addition to imaging various subcortical layers, optical coherence tomography also offers the ability to perform angiography, as the authors demonstrated by visualizing microvasculature in deep regions of white matter. Rather than entirely removing part of the skull, the authors employed a thinned-skull cranial window, which leaves a thin layer of the skull intact and greatly reduces the risk of inflammation. This is an important step towards long-term studies in such animal models.
Although optical coherence tomography features no molecular contrast and cannot rival the fine spatial resolution of multiphoton microscopy, it offers a larger imaging field of view and higher imaging speeds. The extended imaging depth at 1.7 μm demonstrated in this paper offers the ability to conveniently image the full depth of the cortex and enables detailed studies of vascular changes in neurodegenerative disorders.
You must log in to add comments.