Quantitative measurement of optical properties and Hb concentration in a rodent model of inflammatory Meibomian gland dysfunction using spatial frequency domain imaging.

Herein, to investigate a new diagnostic method for Meibomian gland dysfunction (MGD) induced by eyelid inflammation, optical properties and deoxy-hemoglobin (Hb) concentrations in rodent eyelid tissues, including Meibomian glands(MGs), were measured using spatial frequency domain imaging (SFDI). Complete Freund's adjuvant solutions were injected into the eyelid margins of Sprague-Dawley rats to induce MGD. After three weeks, the optical properties and Hb of the MG and non-MG regions of the eyelids were measured ex-vivo using an SFDI system. The comparison of Hb showed that the MGD group exhibited significantly higher values than those of the control group in both regions. The optical properties at 730 and 850 nm for the MG regions in the MGD group were significantly different from those in the control group. In addition, the 630 nm absorption coefficients of both regions were significantly higher in the MGD group than in the control group. Thus, the SFDI technique can detect the increased Hb concentration and changes in the optical properties of the eyelids due to inflammatory MGD in a noncontact manner and has the potential to be used as a novel quantitative diagnostic method for the occurrence of MGD.

The application of SFDI and LSI system to evaluate the blood perfusion in skin flap mouse model.

The aim of this study is to evaluate whether the blood perfusion to tissues for detecting ischemic necrosis can be quantitatively monitored by spatial frequency domain imaging (SFDI) and laser speckle imaging (LSI) in a skin flap mouse model. Skin flaps were made on Institute of Cancer Research (ICR) mice. Using SFDI and LSI, the following parameters were estimated: oxyhemoglobin (HbO2), deoxyhemoglobin (Hb), total hemoglobin (THb), tissue oxygen saturation (StO2), and speckle flow index (SFI). Histologically, epithelium thickness, collagen deposition, and blood vessel count of skin flap tissues were analyzed. Then, the correlation of SFDI and histological results was assessed by application of Spearman rank correlation method. As the result, the number of blood vessels and the percentage of collagen areas showed significant difference between the necrotic tissue group and the non-necrotic one. Especially, the necrotic tissue had a complete epithelial loss and loses its normal structure. We identified that SFDI/LSI parameters were significantly different between non-necrotic and necrotic tissue groups. Especially, all SFDI and LSI parameters measured on the 1st day after surgery showed significant difference between necrotic tissue and non-necrotic tissue. In addition, the number of blood vessel and percentage of collagen area were positively correlated with HbO2 and StO2 among SFDI/LSI parameters. Meanwhile, the number of blood vessel and percentage of collagen area showed the negative correlation with Hb. By applying SFDI and LSI simultaneously to the skin flap, we could quantitatively monitor the blood perfusion and the tissue condition which can help us to detect ischemic necrosis objectively in early stage.

Multimodal sensor-based weight drop spinal cord impact system for large animals.

BACKGROUND CONTEXT: A conventional weight drop spinal cord (SC) impact system for large animals is composed of a high-speed video camera, a vision system, and other things. However, a camera with high speed at over 5,000 frames per second (FPS) is very expensive. In addition, the use of the vision system involves complex pattern recognition algorithms and accurate arrangement of the camera and the target. PURPOSE: The purpose of this study was to develop a large animal spinal cord injury (SCI) modeling system using a multimodal sensor instead of a high-speed video camera and vision system. Another objective of this study was to demonstrate the possibility of the developed system to measure the impact parameters in the experiments using different stiffness materials and an in vivo porcine SC. STUDY DESIGN: A multimodal sensor-based SCI impact system was developed for large animals. The experiments to measure SC impact parameters were then performed using three different stiffness materials and a Yucatan miniature pig to verify the performance of system developed. METHODS: A comparative experiment was performed using three different stiffness materials such as high-density (HD) sponge, rubber, and clay to demonstrate the system and perform measurement for impact parameters such as impact velocity, impulsive force, and maximally compressed displacement reflecting physical properties of materials. In the animal experiment, a female Yucatan miniature pig of 60-kg weight was used. Impact conditions for all experiments were fixed at freefalling object mass of 50 g and height of 20 cm. RESULTS: In the impact test, measured impact velocities were almost the same for the three different stiffness materials at 1.84±0.0153 m/s. Impulsive forces for the three materials of rubber, HD sponge, and clay were 50.88 N, 32.35 N, and 6.68 N, respectively. Maximally compressed displacements for rubber, HD sponge, and clay were 1.93 mm, 3.35 mm, and 15.01 mm, respectively. In the pig experiment, impact velocity, impulsive force, and maximally compressed dural displacement were measured at 1.84 m/s, 13.35 N, and 3.04 mm, respectively. After 3 days from the experiment, paralysis was confirmed for the lower half body of the experimental pig. CONCLUSIONS: Through experiments, it was verified that our proposed system could be used to measure the SC impact parameters and induce SCI for large animals.