Development And Clinical Application Of Fluorescence Measurement System For Tissue Advanced Glycation End Products

With the accelerated development of population aging in China,the incidence rate of type 2 diabetes has increased rapidly.Type 2 diabetes is difficult to cure.Fasting blood glucose is often used to screen type 2 diabetes but with low sensitivity.The incidence rate of diabetic retinopathy(DR)and lower limb atherosclerotic disease(LEAD)is high,and it is the main factor of adult blindness and ulcerative amputation.At present,there is an urgent need for corresponding early detection methods.Studies have shown that advanced glycation end products(AGE)are closely related to the pathogenesis of diabetes and its complications.Advanced glycation end products can be used for early screening of diabetes and its complications.Because the AGE in skin tissue has fluorescence characteristics,the detection of skin AGE by fluorescence spectroscopy has good clinical application for early screening diabetes and its complications.Although many teams have carried out the research on AGE fluorescence detection technology,they are very insufficient in engineering and clinical application research,which limits the widely application of this technology and produces significant social and economic benefits.Therefore,based on the previous research,this dissertation intends to systematically carry out the engineering and clinical research of AGE fluorescence measurement system,and develop a clinically suitable skin AGE fluorescence measurement system.The study established the relationship between AGE and diabetes complications,such as DR and LEAD,so as to lay a solid foundation for the widely use of the technology.The main research contents of this dissertation are as follows:1.The engineering development of tissue AGE fluorescence measurement system is completed.(1)The composition of AGE fluorescent substances and other endogenous fluorophores in tissues were analyzed.The fluorescence characteristics of major AGE and major disruptors collagen,NADH and FAD were determined by three-dimensional fluorescence spectroscopy.(2)Through the experimental study on the interference factors of tissue fluorescence spectrum and diffuse reflection spectrum,the end face and skin contact mode of single point optical fiber probe are determined.The single wavelength optical structure design is carried out.The near ultraviolet LED with the central wavelength of 365nm is used as the excitation light.The visible band multi LED array forms a broadband light source module,and the transmission optical path adopts 3 X 1 optical fiber bundle,with micro spectrometer as the detection unit.(3)It is determined that the multi excitation wavelength optical structure is composed of 340nm,365nm,395nm,415nm,430nm and 455nm LEDs,and the transmission fiber is 4 X 1 optical fiber bundle.(4)According to the needs of users in clinical application scenarios,the electronic,software and structure are designed from the aspects of detecting the operation comfort of doctors' and 'humanized interactive interface',and the development of tissue AGE fluorescence measurement system is completed.2.The calibration method of tissue AGE fluorescence measurement system was established.(1)A traceable integrating sphere system with the functions of radiation response calibration,wavelength calibration and nonlinear calibration is designed and built.(2)The calibration process of tissue AGE fluorescence measurement system is designed,and the calibration of three tissue AGE fluorescence measurement systems is completed.The test results show that the calibration can effectively reduce the detection error and ensure the consistency and repeatability of the tissue AGE fluorescence measurement system.3.The clinical study of AGE fluorescence measurement system based on single wavelength excitation was completed,and the cut-off point value applied to DR evaluation was preliminarily determined.The clinical value of AGEage index in LEAD was proposed and clarified for the first time.(1)By fabricating optical phantoms with different absorption and scattering coefficient,the empirical parameters kx and km of the dual wavelength correction method of the single wavelength AGE fluorescence spectrum measurement system were optimized.The reliability of the algorithm was verified by blood oxygen phantoms and arterial occlusion experiments.(2)In clinical studies,for DR patients whose condition was the most serious threat to vision,the early screening value of AGE was significantly better than HbAlc(P=0.002),and the best cut-off point of AGE is 77.1.(3)Proposed to AGE X Age/100 formed AGEage index.The clinical results show that AGEage may be a simple and effective index for early identification of high-risk population of LEAD,and its best predictive cut-off point is 43.2.The above clinical research provides a strong evidence-based basis for the clinical application of AGE.4.The clinical research of AGE fluorescence measurement system based on multi wavelength excitation has been completed.The diabetes recognition method based on physiological parameters and discrete 3D fluorescence spectrum feature extraction is proposed.(1)The spectral information of 1897 diabetic patients and non-diabetic patients was detected and collected by multi wavelength AGE fluorescence measurement system.The physiological parameters of skin were extracted based on diffuse reflectance spectrum.It was found that the relative concentration of melanin and deoxyhemoglobin and the reduced scattering coefficient and scattering index at 500 um were different.(2)Six discrete three-dimensional fluorescence spectra were decomposed into 26 Gaussian curves by Gaussian multi peak fitting.Each Gaussian spectrum curve had three parameters:intensity,central wavelength position and variance,and a total of 78 fluorescence features are obtained.Further,50 spectral characteristics with differences between groups were further extracted.Finally,combined with physiological parameters and spectral characteristics,logistic regression modeling was used to construct the diabetes recognition model in the training center.The area under the ROC curve of the model reached 0.799,which was significantly higher than that of the single wavelength AGE fluorescence.The results suggested that compared with the single wavelength skin AGE fluorescence method,the discrete three-dimensional fluorescence spectroscopy maybe have higher application value in the identification of diabetes.In conclusion,the engineering and clinical application of AGE fluorescence measurement system are systematically studied in this dissertation.The skin AGE fluorescence detection system has been applied in China for screening the high-risk population of diabetes and diabetic patients.It is expected to create better social and economic benefits.