Theranostic cranial implant for hyperspectral light delivery and microcirculation imaging without scalp removal

Abstract

Light based techniques for imaging, diagnosing and treating the brain have become widespread clinical tools, but application of these techniques is limited by optical attenuation in the scalp and skull. This optical attenuation reduces the achievable spatial resolution, precluding the visualization of small features such as brain microvessels. The goal of this study was to assess a strategy for providing ongoing optical access to the brain without the need for repeated craniectomy or retraction of the scalp. This strategy involves the use of a transparent cranial implant and skin optical clearing agents, and was tested in mice to assess improvements in optical access which could be achieved for laser speckle imaging of cerebral microvasculature. Combined transmittance of the optically cleared scalp overlying the transparent cranial implant was as high as 89% in the NIR range, 50% in red range, 24% in green range, and 20% in blue range. In vivo laser speckle imaging experiments of mouse cerebral blood vessels showed that the proposed optical access increased signal-to-noise ratio and image resolution, allowing for visualization of microvessels through the transparent implant, which was not possible through the uncleared scalp and intact skull.

Nanocrystalline Yttria-Stabilized Zirconia Ceramics for Cranial Window Applications

“…However, transgranular fractures will occur when numerous dislocations are formed in the crystal grains . Our previous studies indicated that the CAPAD-processed 8YSZ disc had a hardness of 13.2 ± 0.1 GPa, whereas the SPS-processed 8YSZ_P disc showed a similar hardness of 13.9 ± 0.7 GPa, which suggested that the CAPAD and SPS processes may have limited effects on the hardness of YSZ discs.…”

Recent Advances in the Laser Radiation Transport through the Head Tissues of Humans and Animals – A Review

“…The skull and OCS scattering both disorder the speckle pattern that was created by the brain hemodynamics. The reduction in border sharpness of the vessels imaged through the intact skull vs. OCS + implant suggests that the skull has a higher blurring effect [48].…”

“…The noninvasive interactions with tissue of photons within this energy range have been used in numerous approaches to assess brain health and treat its diseases. The application of transparent cranial implants holds the transformative potential for facilitating the diagnosis and treatment of a wide variety of brain pathologies and neurological disorders [48]. Implementing this implant in the current cranial prostheses or a separate implantation of "Window to the Brain" (WttB) implant (e.g.…”

“…on a drilled hole in the skull) enables delivery to and/or acquisition of light from the brain, in real-time, without the need for scalp removal for various post-operation applications. In the study [48], the light delivery improvement by WttB implant coupled with optical cleared scalp (OCS) in a set of ex vivo optical characterization measurements was assessed. Additionally, the feasibility of through-scalp brain microcirculation imaging using the implant in vivo was evaluated.…”