Conventional dual-input state PS-OCT incorrectly assumes that the two probing input states provide equally reliable measurements. In this work, we overcome this assumption by adapting a maximum-likelihood framework which combines all input state and spectral bin measurements to find the most likely sample Jones matrix. This processing method (MLDIPS) shows a significantly reduced retardance noise floor as well as improved qualitative characterization of white matter versus grey matter in porcine brain tissue, displaying better contrast to conventional dual-input processing.
Significant technical and optical advancements are required for intraoperative optical coherence tomography (OCT) to perform boundless surgical applications in otology, since the translation of OCT for surgical-microscope facilitates the simultaneous OCT and microscopic visualization of soft tissue structures of the surgical region with a high-resolution in real-time. Herein, we developed an augmented-reality intrasurgical OCT microscope system with an extended 280 mm working distance, which simply provides a sufficient space for the manipulation during surgeries compared to conventional techniques. Ex vivo experiments were initially performed to evaluate the enhanced system performances and secondly, the developed system was well-utilized to clinically assess the preliminary findings of tympanomastoidectomy in six patients with chronic otitis media. The OCT system evaluated the residual inflammation of region of interest in the mastoid bone and most importantly OCT was sufficiently useful for visualizing the connection between the graft and remnant tympanic membrane intraoperatively. Use of this extended-working distance OCT integrated surgical-microscope enables the surgeons to precisely define the aforementioned surgical requirements, while performing intraoperative imaging over the complete range.
In this study, we monitored the optical clearing effects by immersing ex vivo guinea pig cochlea samples in ethylenediaminetetraacetic acid (EDTA) to study the internal microstructures in the morphology of guinea pig cochlea. The imaging limitations due to the guinea pig cochlea structures were overcome by optical clearing technique. Subsequently, the study was carried out to confirm the required approximate immersing duration of cochlea in EDTA-based optical clearing to obtain the best optimal depth visibility for guinea pig cochlea samples. Thus, we implemented a decalcification-based optical clearing effect to guinea pig cochlea samples to enhance the depth visualization of internal microstructures using swept source optical coherence tomography (OCT). The obtained nondestructive two-dimensional OCT images successfully illustrated the feasibility of the proposed method by providing clearly visible microstructures in the depth direction as a result of decalcification. The most optimal clearing outcomes for the guinea pig cochlea were obtained after 14 consecutive days. The quantitative assessment results verified the increase of the intensity as well as the thickness measurements of the internal microstructures. Following this method, difficulties in imaging of internal cochlea microstructures of guinea pigs could be avoided. The obtained results verified that the depth visibility of the decalcified ex vivo guinea pig cochlea samples was enhanced. Therefore, the proposed EDTA-based optical clearing method for guinea pig can be considered as a potential application for depth-enhanced OCT visualization.
The aim of this study was to analyze the effectiveness of decalcification using ethylenediaminetetraacetic acid (EDTA) as an optical clearing method to enhance the depth visibility of internal soft tissues of cochlea. Ex vivo mouse and guinea pig cochlea samples were soaked in EDTA solutions for decalcification, and swept source optical coherence tomography (OCT) was used as imaging modality to monitor the decalcified samples consecutively. The monitored noninvasive cross-sectional images showed that the mouse and guinea pig cochlea samples had to be decalcified for subsequent 7 and 14 days, respectively, to obtain the optimal optical clearing results. Using this method, difficulties in imaging of internal cochlea microstructures of mice could be evaded. The obtained results verified that the depth visibility of the decalcified ex vivo samples was enhanced.
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