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Fluorescent Technology in the Assessment of Metabolic Disorders in Diabetes
Published in Andrey V. Dunaev, Valery V. Tuchin, Biomedical Photonics for Diabetes Research, 2023
Elena V. Zharkikh, Viktor V. Dremin, Andrey V. Dunaev
It seems promising to apply together the methods of fluorescence and microcirculation analysis in diabetes practice, as it will allow assessing both metabolic and vascular disorders in the patient’s body. However, to the best of our knowledge, there is a limited amount of research being done in this area. A recent animal study assessing wound healing in diabetes used multimodal optical imaging based on the combined use of multiphoton microscopy, second harmonic generation, optical coherence tomography, angiography, and FLIM [69]. The developed method of multimodal study has proved its effectiveness in assessing the pharmacodynamics of the wound region in different therapy approaches and seems promising for further use in research, since it allows us to assess metabolic and structural changes in the biological tissue, as well as to monitor the process of angiogenesis. The method of laser Doppler flowmetry is also of some interest when used together with fluorescent methods to study metabolic and microcirculatory disorders in diabetes.
Automatic Detection of Early Signs of Diabetic Retinopathy Based on Feature Fusion from OCT and OCTA Scans
Published in Ayman El-Baz, Jasjit S. Suri, Big Data in Multimodal Medical Imaging, 2019
Nabila Eladawi, Ahmed ElTanboly, Mohammed Elmogy, Mohammed Ghazal, Ali Mahmoud, Ahmed Aboelfetouh, Alaa Riad, Magdi El-Azab, Jasjit S. Suri, Guruprasad Giridharan, Ayman El-Baz
Diabetic retinopathy (DR) affects the blood circular system in the eye. It is the most common cause of vision loss among people with diabetes. In addition, it is the leading cause of vision impairment and blindness among working-age people. The earlier stage of DR is called non-proliferative diabetic retinopathy (NPDR). In the NPDR stage, abnormalities, such as microaneurysms, vessel dilation and tortuosity, foveal avascular zone (FAZ) enlargement, and capillary dropout, start to appear [1–8]. The more advanced stage of the disease is proliferative diabetic retinopathy (PDR). PDR is characterized by retinal and/or optic nerve neovascularization. Ophthalmologists aim to prevent and treat DR to avoid vision loss, not to restore it. To be able to do so, early detection of DR is needed. Since microvascular pathology causes DR, we need imaging techniques that can visualize retinal vasculature. The standard clinical techniques to visualize the ocular vasculature are fluorescein angiography (FA) and indocyanine green angiography (ICGA). Due to their invasiveness and cost, they cannot be used routinely to examine DR. Optical coherence tomography angiography (OCTA) depends on repeated B-scans that are taken in rapid succession. Due to the noninvasiveness character of OCTA, it is ideal for monitoring and detecting DR in diabetic patients. OCTA can easily detect capillary dropout among other abnormalities that appear in the early stage of DR [4,9–15].
Observation of rhegmatogenous retinal detachment associated with choroidal detachment after vitrectomy by optical coherence tomography angiography
Published in The Imaging Science Journal, 2019
Ying Zhou, Qin-Yu Ge, Zhi-Feng Wu, Xiao-Mei Meng
The recently emerging optical coherence tomography angiography (OCTA) is a non-invasive, non-divergent angiography technique based on OCT that not only displays the structure of different layers of the retina and choroid, but also the blood flow of each layer in the graph. OCTA has the advantages of high resolution, non-invasiveness, and fewer side effects. It can layer the blood vessels in the retina and provide a three-dimensional image. Compared with the previous OCT, OCTA can achieve ultra-clear microangiography visualization, which is very helpful for the diagnosis and follow-up of fundus diseases. OCTA can not only observe choroidal thickness but also detect blood flow density in the superficial and deep retina, foveal avascular area (FAZ), retinal foveal thickness (FT), and subfoveal choroidal thickness (SFCT). Although OCTA is still in the process of continuous development, OCTA has now been able to display unprecedented blood flow images of all vascular layers, greatly expanding our understanding of fundus diseases [1].
Optical coherence tomography angiography (OCTA) flow speed mapping technology for retinal diseases
Published in Expert Review of Medical Devices, 2018
Malvika Arya, Ramy Rashad, Osama Sorour, Eric M. Moult, James G. Fujimoto, Nadia K. Waheed
Optical coherence tomography angiography (OCTA) is a noninvasive imaging technique that allows for depth-resolved, high-resolution imaging of retinal and choroidal vasculature. Qualitative and quantitative analysis using OCTA has been essential in further understanding the pathogenesis and progression of various vascular pathologies, such as diabetic retinopathy.A limitation of OCTA is that it offers an image depicting either the presence or absence of flow, without information about flow velocities.Variable interscan time analysis (VISTA) overcomes the grayscale limitation of OCTA and provides a color-coded map of relative retinal blood flow speeds. VISTA has been used to further analyze retinal vascular diseases, such as age-related macular degeneration, including choroidal neovascularization and geographic atrophy, diabetic retinopathy, and aneurysmal type 1 neovascularization.Further development of VISTA and its flow speed mapping capabilities may allow OCTA to become an essential tool for screening purposes.