The evaluation of burn degree is a key step to guide the treatment of patients with thermal injury. In this work, multiple parameters including intensity, accumulative and local birefringence features based on dual-detection Polarization Sensitive Optical Coherence Tomography (PS-OCT) are proposed to quantitatively describe the information of skin burn. The results demonstrated that the intensity and the cumulative phase retardation and local phase retardation information of skin decrease with the burn degrees, since thermal damage to the collagen structure of dermal layer. In addition, the slopes of accumulative phase retardation dependent of depth are extracted for characterization of normal and damaged skins. Finally, the local phase retardation not only distinguishes the normal and damaged skin, but also evaluates the burn depth. Therefore, multiple parameters using dual-detection PS-OCT can detect the anisotropic change of birefringence of skin tissue caused by thermal injury and reveal the potential for burn assessment.
In this study, the modified spectral domain polarization-sensitive optical coherence tomography (SD PS-OCT) is proposed for determining the birefringence of the myocardial tissue. In this modified SD PS-OCT, the circular polarization state of light was generated before entering the beam splitter. Thus, the polarization states in the reference and sample arms are both circular, and the symmetry between them is good without using additional Quarter-Wave Plate (QWP), which reduce the dispersion effect. The results demonstrated that theoretical analysis for determination of birefringence including the phase retardance and the fast axis orientation based on Stokes parameters of backscattered from biological tissue, which is different from the traditional SD PS-OCT. In addition, the phase retardance and the fast axis orientation was used to differentiate the myocaridal tissue in the diastole of the cardiac cycle the from that in the systole of the cardiac cycle. The findings suggest that the SD PS-OCT be a potential tool for the real-time monitoring the change of the myocardial wall during the cardiac cycle.
In this study, surgical operation for the myocardial ischemia of rat was used to simulate the model of critically ill patients. Speckle variance optical coherence tomography was applied to study the effects of myocardial ischemia on blood microcirculation. The main method is to simulate the severe condition through the heart ligation operation in rats, and then the OCT system is used to image the ear of rats. First of all, the variance operation is performed on the same position of the structure map through speckle variance algorithm, so as to obtain the blood flow intensity information. Finally, the vascular morphological structure can be roughly seen through the basic vascular enhancement algorithm. A comparison of vascular images before and after heart ligation surgery revealed that surgery had a significant effect on the circulation of microvessels, and many microvessels were lost intermittently after surgery. Accurate in vivo study model is very important to obtain OCT images and accurate analysis, and it is of great value to promote the development of microangiography4 and its clinical application.
Optical coherence tomography (OCT) is a biomedical imaging technology that uses interference information generated by two light waves to measure and evaluate biological tissues. Because of its high sensitivity, high resolution, and non-destructive testing, it is widely used in various fields. In this paper, OCT is used to detect and evaluate the reproduction of the three bacteria. At the same time, we also use a 20-fold objective lens to observe the morphology of the three bacteria at the position of the sample arm of the OCT. In the experiment, three groups of experimental data were collected, which were pictures collected after two hours, four hours, and five hours of bacterial culture. From the experimental data, the morphology and colony reproduction changes of the three bacteria can be observed; after 4 hours of reproduction, the morphology of E. coli and aeruginosa can be observed; Morphological structure of the three bacteria could be observed after 5 hours of reproduction; through the three-dimensional reconstruction of the experimental data, the three-dimensional morphology of the bacteria can be seen more clearly, which is more conducive to the identification of bacterial species. Experimental results show that OCT can be used to detect bacterial organisms on the order of micrometers, and can observe the reproduction process and morphology of bacteria in different periods, to identify bacterial species. This is of great help in the non-invasive identification of bacterial types in clinical applications of biomedicine.
Photothermal therapy of tumors has become an important method. In recent years, the method has been widely studied in tumor therapy, and the corresponding results has been obtained well. However, it is still not been solved the effects of the heat on the tumor and its surrounding tissues, and the temperature control in corresponding tissues during the treatment process. In our study, the mouse skin was chosen as the research object. Infrared thermal imager and optical coherence tomography (OCT) were combined to monitor the photothermal therapy in real time in vivo. Temperature and morphological structure were obtained during the photothermal therapy process. The results will provide effective guidance for the photothermal therapy of tissue.
To explore the damage range in the photothermal treatment at different temperatures, a temperature-feedback photothermal control system was developed. The system used an infrared thermal imager to noninvasively monitor the temperature .so it could avoid the damage caused by thermocouple measurement and apply the PID controller to achieve the desired temperature(1). the range of damage at the surface and the depth of internal damage were recorded at the different temperatures, which are based on the temperature-feedback photothermal control system. Finally, the recorded data are used to fit the curve by linear regression, and the damage depth was predicted according to the range of external damage at the surface. The technique could be a potential application for monitoring tumor treatment.
Time-division-detected fiber-optic Mueller OCT system was developed for radiumdium. In this system, Mueller matrix was used to measure the polarization characteristics of the anisotropic scattering medium. There are four optical channels for different polarization types in reference arm: horizontal , vertical , 45° linearly polarized , and circular polarization. Meanwhile the sample arm uses rotary wave plate to achieve the four polarizations of light. The optical switches are used to select different channels in the reference arm, and the polarized light of each channel interfere with the polarized light backscattering from the sample. Therefore, the sixteen OCT images from different polarization were obtained to calculate Mueller matrix of sample. Finally, this OCT system was applied for quantitatively characterize isolated pig myocardium structure.
In recent years, because of its safety and effectiveness, photothermal therapy has also become an important way to treat malignant tumors. However, due to the photothermal conversion effect, the heat deposited in the lesion area will spread to other parts of the biological tissue in the way of heat conduction in the treatment process, which is likely to cause some damage to other normal tissues. Optical coherence tomography (OCT) can reconstruct internal high-resolution images to observe the extent of tissue injury. The image of tissue damage structure obtained by OCT system can observe not only the external damage of tissue, but also the internal damage of tissue. The OCT images of damage tissue are taken as the research object, and a semantic segmentation model of deep learning was constructed to separate and visualize the damage tissue, which can help to accurately identify the damage range quickly.
Objective: To investigate the feasibility of Mueller optical coherence tomography (OCT) imaging of myocardial fiber structures at different locations. METHODS: A pig heart was taken as a sample, and the Mueller OCT system was used to perform two-dimensional scanning on different positions of the pig heart test sample, and the collected image data was processed by digital image processing method to observe the basic structure of the myocardium at different positions. RESULTS: The images of the isolated pig heart after scanning by the OCT system were processed by the relevant algorithm. The images of 16 elements in the Mueller matrix of the myocardial structure at different locations were also observed. It can also be seen that there is some different of the myocardial fiber structures in different depth directions. Conclusion: Mueller Optical coherence tomography (OCT) can be successfully used to image myocardial fiber structures at different locations.
To minimize thermal injury, the temperature monitoring with a proportional-integrative-derivative (PID) controller was applied for photothermal treatment of tumors. The thermocouple was used to estimate the temperature. However, it is impossible for thermocouple to measure the spatio-temporal developments of the temperature in tissue. In this work, we present temperature feedback-controlled photothermal treatment based on thermal infrared imager. Experiments demonstrated comparable thermal behaviors in temperature distribution and the degree of irreversible tissue denaturation for the different PID-controlled applications. Integration of temperature feedback with thermal infrared imager-assisted photothermal treatments can provide a feasible therapeutic modality to treat tumors in an effective manner.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.