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Lipid Emulsion–Based OCT Angiography for Ex Vivo Imaging of the Aqueous Outflow Tract
摘要： PURPOSE. Contrast agents applicable for optical coherence tomography (OCT) imaging are rare. The intrascleral aqueous drainage system would be a potential application for a contrast agent, because the aqueous veins are of small diameter and located deep inside the highly scattering sclera. We tested lipid emulsions (LEs) as candidate OCT contrast agents in vitro and ex vivo, including milk and the anesthetic substance Propofol. METHODS. Commercial OCT and OCT angiography (OCTA) devices were used. Maximum reflectivity and signal transmission of LE were determined in tube phantoms. Absorption spectra and light scattering was analyzed. The anterior chamber of enucleated porcine eyes was perfused with LEs, and OCTA imaging of the LEs drained via the aqueous outflow tract was performed. RESULTS. All LEs showed a significantly higher reflectivity than water (P < 0.001). Higher milk lipid content was positively correlated with maximum reflectivity and negatively with signal transmission. Propofol exhibited the best overall performance. Due to a high degree of signal fluctuation, OCTA could be applied for detection of LE. Compared with blood, the OCTA signal of Propofol was significantly stronger (P ? 0.001). As a proof of concept, time-resolved aqueous angiography of porcine eyes was performed. The three-dimensional (3D) structure and dynamics of the aqueous outflow were significantly different from humans. CONCLUSIONS. LEs induced a strong signal in OCT and OCTA. LE-based OCTA allowed the ability to obtain time-resolved 3D datasets of aqueous outflow. Possible interactions of LE with inner eye's structures need to be further investigated before in vivo application.
关键词： lipid emulsion,propofol,optical coherence tomography angiography,aqueous flow
更新于2025-09-19 17:15:36
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Does low-level laser therapy decrease pain and swelling after surgical removal of lower third molar? a randomized crossover clinical trial
摘要： Comparison of propofol tci versus sevoflurane in the extraction of four 3rd molar teeth Background: Extraction of four third molar teeth under general anesthesia is one of the most common day-case procedures performed in operating theatres. Sevoflurane and propofol TCI are the two most common methods of maintaining anaesthesia. In the past, it was difficult to compare these two different anaesthetic techniques, as there was no way to standardize the depth of anaesthesia. The new depth of anaesthesia monitors such as Bispectral Index (BIS) monitor and Entropy monitor developed by Datex-Ohmeda allow us to control the depth of anaesthesia during the intraoperative period. Using a specified depth of anaesthesia, we sought to compare these two different methods of anesthesia with respect to haemodynamic stability, and postoperative measures of sedation, nausea, vomiting and pain. Objectives: To compare haemodynamic, emergence and recovery characteristics of total intravenous anesthesia using propofol Target Controlled Infusion (TCI) versus sevoflurane anesthesia for extraction of four 3rd molar teeth. Methods: 100 patients undergoing extraction of 4 3rd molar teeth under general anesthesia were randomized to one of two groups. Group 1 received propofol TCI-oxygen for induction followed by propofol TCI-oxygen-air for maintenance. Group II received propofol bolus of 2 mg/kg for induction followed by sevoflurane-oxygen-air for maintenance. Depth of anesthesia during the maintenance phase was kept at 40-55 using entropy monitoring. Heart rate, blood pressure, operating time, time to emergence, nausea and vomiting, sedation and VAS pain scores were measured for each group. Findings: Demographics including age, sex, weight and height were not statistically different between the two groups. The blood pressure was higher after intubation (P = 0.007) and injection of local anesthesia (P = 0.004) for the propofol group compared to the sevoflurane group with a statistically significant reflex bradycardia (P = 0.028). Intraoperatively, the variation in blood pressure and heart rate was higher with propofol but did not reach statistical significance (P = 0.1). Time to emergence was statistically significant (P = 0.02) but clinically not significant (Mean: Propofol 2.5mins vs sevoflurane 2.94 mins) Postoperatively, the propofol group was less sedated at 30 minutes (0.02 Vs 0.12) but also did not reach statistical significance (P = 0.065). Conclusion: Propofol TCI and sevoflurane are both reasonable alternatives for induction and maintenance of anesthesia for short day-case surgery. Propofol TCI does not blunt haemodynamic response to sudden, severe stimuli as well as sevoflurance, which may be an issue in patients with cardiac co-morbidities. Propofol TCI is also cheaper and produces less greenhouse gases than sevoflurane anesthesia but utilizes more equipment, which may also influence your decision of which anesthetic technique to use.
关键词： third molar teeth extraction,propofol TCI,sevoflurane,general anesthesia,haemodynamic stability
更新于2025-09-12 10:27:22
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[Institution of Engineering and Technology 2015 IET International Conference on Biomedical Image and Signal Processing (ICBISP 2015) - Beijing, China (19 Nov. 2015)] 2015 IET International Conference on Biomedical Image and Signal Processing (ICBISP 2015) - Altered hub configurations during propofolinduced loss of consciousness
摘要： Graph-theoretical analysis of human brain functional networks based on functional magnetic resonance imaging (fMRI) have supported the existence of highly connected hub regions that may play a key role in brain function and cognition. Here, we investigated the hub distributions of 16 healthy volunteers during wakefulness and propofol-induced loss of consciousness (both light sedation and deep sedation). Functional connectivity between 160 cortical and subcortical regions was measured by correlation analysis and then thresholded to construct undirected graphs. We found that during wakefulness state highly connected hubs included bilateral angular, precuneus, posterior cingulate (PCC), superior frontal gyrus (SFG), ventrolateral frontal cortex (vFC), supplementary motor area (SMA) and pre-SMA, most of the which were in the default-mode network (DMN). However, during light sedation, we observed that hubs were mainly in posterior part of the brain (inferior parietal lobule, inferior temporal, occipital). And the major hubs during deep sedation were in the occipital lobe and cerebellum. Compared with wakefulness, the hub structures were significantly changed from heteromodal association cortex to unimodal association and primary cortices. Our findings support a reduction in information integration and a topological reconfiguration during decreasing levels of consciousness.
关键词： propofol,functional MRI,hub,consciousness,graph theory
更新于2025-09-10 09:29:36