Shenzhen Bay laboratory vision
Recently, Ren Qiushi team of Peking University / Shenzhen Bay laboratory proposed a new multimodal eye function imaging technology for noninvasive detection of eye meridian and retinal dynamic oxygen metabolism, Part of the research results form the paper functional imaging of human retina using integrated multispectral and laser specklecontract imaging, which is published in the Journal of biophotonics, an authoritative international journal of biomedical photonics.
More than 80% of the external information obtained by the human brain is perceived through the eyes, so eye health is very important to ensure people's quality of life. China has a large population base and a large number of visual disabilities. With the increasing aging of society, blindness, such as age-related macular degeneration, diabetic retinopathy, retinal vascular obstruction and glaucoma, is a serious threat to the visual health of the elderly.
In addition, the human eye is also a natural window to observe brain cognition, human metabolism, human microcirculation and cardiovascular and cerebrovascular states. A variety of major chronic diseases may be complicated or secondary to eye diseases. Clinical studies have also confirmed that fundus lesions have hallmarks of hypertension, stroke, coronary heart disease, neurodegenerative diseases, diabetes and kidney disease, and can be used as criteria for early screening and diagnosis of diseases. Therefore, the research on an intelligent multimodal visual function inspection technology and equipment, combined with big data and artificial intelligence technology, is of great significance to save medical resources and promote people's health.
Recently, Ren Qiushi team of Peking University / Shenzhen Bay laboratory proposed a new multimodal eye function imaging technology for noninvasive detection of eye meridian and retinal dynamic oxygen metabolism, Part of the research results form the paper functional imaging of human retina using integrated multispectral and laser specklecontract imaging, which is published in the Journal of biophotonics, an authoritative international journal of biomedical photonics.
Retina is the only microcirculation system that can be directly observed in human body, and it is also one of the organs with the highest oxygen consumption in human body. The structural and functional information of retinal microcirculation has important guiding significance for disease screening, diagnosis and prognosis. With the development of optical imaging technology, the evaluation of retinal microcirculation has gradually changed from structural analysis to functional analysis. Retinal multispectral imaging technology can not only evaluate retinal oxygen saturation, but also realize retinal structure imaging at different levels for better lesion evaluation. On the other hand, non-invasive and wide field retinal perfusion imaging information can be obtained by laser speckle imaging technology, which provides effective information for retinal blood supply and hemodynamic analysis. However, the existing retinal structure and function imaging instruments are independent of each other, which is difficult to realize synchronous measurement and evaluation, which greatly limits the analysis of retinal structure and function. Professor Ren Qiushi's team organically integrated multispectral imaging technology with laser speckle imaging technology, combined with eye movement analysis and pupil detection technology, and proposed a new multi-mode eye function imaging analysis technology (shown in Figure 1), which can realize retinal multispectral imaging, fundus color synthesis image, retinal vessel diameter measurement, retinal oxygen saturation measurement Retinal and choroidal perfusion imaging, retinal blood flow pulsation analysis, retinal oxygen metabolism dynamics and other structural and functional information provide a powerful tool for more comprehensive evaluation of the characteristics of retinal microcirculation.
Figure 1 Multimodal eye function imaging analysis system (left: imaging mode; right: engineering prototype)
The system adopts automatic focusing technology and one key to realize data acquisition. The acquisition time of multispectral image is 1s and that of laser speckle image is 5S. Figure 2 (a) shows the results of 6-wavelength multispectral images (white characters in the image identify the corresponding wavelength). With the increase of wavelength, the retinal structure information at different depths can be observed, which is of reference significance for the diagnosis of lesions. In addition, the system provides a scalable light source interface, which can be further extended to 12 wavelengths, which is not only helpful for the analysis of structural information of different layers of retina, but also for retinal microcirculation Tissue composition analysis also has potential value. Taking into account the habit of ophthalmologists in reading pictures, this technology carries out color synthesis of 470 nm, 550 nm and 600 nm multispectral images. As shown in Fig. 2 (b), the wavelength used for synthesis can be personalized according to the needs of doctors, and the relevant lesions can be more intuitively identified through color information. Blood oxygen saturation (the percentage of oxygenated hemoglobin and reduced hemoglobin in blood) is one of the important means to evaluate the oxygen supply. At the wavelength of 550 nm, the absorption capacity of oxygenated hemoglobin and reduced hemoglobin is approximately equal; At the wavelength of 600 nm, the absorption capacity of oxygenated hemoglobin and reduced hemoglobin is quite different. Based on this principle, this study analyzes retinal oxygen saturation through 550nm and 600nm multispectral images, as shown in Figure 2 (c). The closer the image is to red, the higher the blood oxygen saturation; The closer to blue, the lower the oxygen saturation. Fig. 2 (d) shows the average blood flow perfusion image of the retina and choroid of the subject. The closer to white in the image, the higher the blood flow rate; The closer to black, the lower the blood flow rate. Figure 2 (E) shows the pulsation curve of retinal blood flow rate with heart beat. The analysis of pulsation curve can not only evaluate the information such as heart rate, systolic time and diastolic time, but also has potential value for the analysis of vascular elasticity and hemodynamics. Finally, figure 2 (f) shows the distribution of retinal blood velocity at different times. With the heart beating, the retinal blood velocity also increases and decreases periodically. White characters in the image indicate different times. The closer to red, the higher the blood flow rate; The closer to blue, the lower the blood flow rate.
Figure 2 Retinal structure and function imaging results.
(a) Multispectral image; The white text in the image is the corresponding wavelength (b) color fundus synthetic image; (c) retinal oxygen saturation profiles calculated from 550 nm and 600 nm images were synthesized by 470 nm, 550 nm and 600 nm. The blue annular area is used to calculate the average retinal oxygen saturation; (d) Mean blood perfusion image showing retinal and choroidal vessels; (e) Retinal microcirculation pulse waveform (f) blood perfusion images at different times.
Abbreviation: so Ω blood oxygen saturation; LSC laser speckle contrast ratio (1 / LSC) ² (positive correlation with blood flow rate)
Ren Qiushi's team has been committed to the technical development of multimodal eye function imaging for many years, and the team will continue to conduct in-depth research, optimization and upgrading of this technology. At present, the team is cooperating with major hospitals to carry out large-scale clinical research on multimode eye functional imaging analysis technology in Ophthalmology, neurology, cardiology and nephrology. It is expected to carry out more comprehensive research on disease screening, diagnosis and prognosis, so as to make the window of mind escort health. The research was supported by the national biomedical imaging equipment fund, the National Natural Science Foundation of China, the Beijing Natural Science Foundation, and the Shenzhen Nanshan innovation and business development fund of Shenzhen Science and technology plan.
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Thesis title:Functional imaging of human retina using integrated multispectral and laser speckle contrast imaging
Original link:http://doi.org/10.1002/jbio.202100285