Retinal Vascular Imaging Application in Women’s Reproductive Health:Clinical Implications and Future Directions

Over the past two decades,population-based studies employing semiautomatic computer-assisted programs have uncovered associations between retinal microvascular features and various systemic conditions.As the recognition of retinal imaging in cardiometabolic health grows,there is increasing evidence supporting its application in women’s health,particularly during the reproductive age.This review aims to summarize the indications of retinal imaging in women’s health and intergenerational health,where suboptimal retinal imaging has been found to mirror pathological systemic changes,such as suboptimal hemodynamic circulation,inflammation,endothelial dysfunction,oxidative stress,and hypoxia in vivo.Findings from Singapore Growing Up in Singapore Towards Healthy Outcomes and Singapore Preconception Study of Long-Term Maternal and Child Outcomes cohorts have reported serial changes in retinal conventional microvascular features(e.g.,retinal arteriolar narrowing,retinal venular widening)and retinal geometric microvascular features(e.g.,sparse fractal dimension,enlarged branching angle,and increased curvature tortuosity)during the preconception and antenatal phases.These morphological abnormalities were found to be related to female fertility,maternal antenatal health conditions,postnatal maternal cardiometabolic health,and intergenerational health in the fetus.Given the compelling evidence of the ability to detect microvascular changes through noninvasive methods at an early stage,retinal imaging holds the potential to facilitate timely interventions,mitigate the progression of complications,and prevent adverse pregnancy outcomes.Looking ahead,the convergence of artificial intelligence and advanced imaging techniques heralds a promising era in women’s health research and clinical practice.

Deep tissue near-infrared imaging for vascular network analysis

Subcutaneous vein network plays important roles to maintain microcirculation that is related to some diagnostic aspects.Despite developments of optical imaging technologies,still the difficulties about deep skin vascular imaging have been continued.On the other hand,since hemoglobin con-centration of human blood has key role in the veins imaging by optical manner,the used wavelength in vascular imaging,must be chosen considering absorption of hemoglobin.In this research,we constructed a near infrared(NIR)light source because of lower absorption of hemoglobin in this optical region.To obtain vascular image,reflectance geometry was used.Next,from recorded images,vascular network analysis,such as calculation of width of vascular of interest and complexity of selected region were implemented.By comparing with other modalities,we observed that proposed imaging system has great advantages including nonionized radiation,moderate penetration depth of 0.5-3 mm and diameter of 1 mm,cost-effective and algorit hmic simplicity for analysis.

Exploratory study of non-invasive,high-resolution functional macular imaging in subjects with diabetic retinopathy

AIM:To evaluate a high-resolution functional imaging device that yields quantitative data regarding macular blood flow and capillary network features in eyes with diabetic retinopathy(DR).METHODS:Prospective,cross-sectional comparative case-series in which blood flow velocities(BFVs)and noninvasive capillary perfusion maps(nCPMs)in macular vessels were measured in patients with DR and in healthy controls using the Retinal Functional Imager(RFI)device.RESULTS:A total of 27 eyes of 21 subjects were studied[9 eyes nonproliferative diabetic retinopathy(NPDR),9 eyes proliferative diabetic retinopathy(PDR)and 9 controls].All diabetic patients were type 2.All patients with NPDR and 5 eyes with PDR also had diabetic macular edema(DME).The NPDR group included eyes with severe(n=3)and moderate NPDR(n=6),and were symptomatic.A significant decrease in venular BFVs was observed in the macular region of PDR eyes when compared to controls(2.61±0.6 mm/s and 2.92±0.72 mm/s in PDR and controls,respectively,P=0.019)as well as PDR eyes with DME compared to NPDR eyes(2.36±0.51 mm/s and 2.94±1.09 mm/s in PDR with DME and NPDR,respectively,P=0.01).CONCLUSION:The RFI,a non-invasive imaging tool,provides high-resolution functional imaging of the retinal microvasculature and quantitative measurement of BFVs in visually impaired DR patients.The isolated diminish venular BFVs in PDR eyes compared to healthy eyes and PDR eyes with DME in comparison to NPDR eyes may indicate the possibility of more retinal vein compromise than suspected in advanced DR.

Polymeric dual-modal imaging nanoprobe with two-photon aggregation-induced emission for fluorescence imaging and gadolinium-chelation for magnetic resonance imaging

Nanoprobes that offer both fluorescence imaging(FI)and magnetic resonance imaging(MRI)can provide supplementary information and hold synergistic advantages.However,synthesis of such dual-modality imaging probes that simultaneously exhibit tunability of functional groups,high stability,great biocompatibility and desired dual-modality imaging results remains challenging.In this study,we used an amphiphilic block polymer from(ethylene glycol)methyl ether methacrylate(OEGMA)and N-(2-hydroxypropyl)methacrylamide(HPMA)derivatives as a carrier to conjugate a MR contrast agent,Gd-DOTA,and a two-photon fluorophore with an aggregation-induced emission(AIE)effect,TPBP,to construct a MR/two-photon fluorescence dual-modality contrast agent,Gd-DOTA-TPBP.Incorporation of gadolinium in the hydrophilic chain segment of the OEGMA-based carrier resulted in a high r_(1)value for Gd-DOTA-TPBP,revealing a great MR imaging resolution.The contrast agent specifically accumulated in the tumor region,allowing a long enhancement duration for vascular and tumor contrast-enhanced MR imaging.Meanwhile,coupling TPBP with AIE properties to the hydrophobic chain segment of the carrier not only improved its water solubility and reduced its cytotoxicity,but also significantly enhanced its imaging performance in an aqueous phase.Gd-DOTA-TPBP was also demonstrated to act as an excellent fluorescence probe for two-photon-excited bioimaging with higher resolution and greater sensitivity than MRI.Since high-resolution,complementary MRI/FI dual-modal images were acquired at both cellular and tissue levels in tumor-bearing mice after application of Gd-DOTA-TPBP,it has great potential in the early phase of disease diagnosis.

A promising approach for quantifying focal stroke modeling and assessing stroke progression:optical resolution photoacoustic microscopy photothrombosis

To investigate the mechanisms underlying the onset and progression of ischemic stroke,some methods have been proposed that can simultaneously monitor and create embolisms in the animal cerebral cortex.However,these methods often require complex systems and the effect of age on cerebral embolism has not been adequately studied,although ischemic stroke is strongly age-related.In this study,we propose an optical-resolution photoacoustic microscopy-based visualized photothrombosis methodology to create and monitor ischemic stroke in mice simultaneously using a 532 nm pulsed laser.We observed the molding process in mice of different ages and presented age-dependent vascular embolism differentiation.Moreover,we integrated optical coherence tomography angiography to investigate age-associated trends in cerebrovascular variability following a stroke.Our imaging data and quantitative analyses underscore the differential cerebrovascular responses to stroke in mice of different ages,thereby highlighting the technique's potential for evaluating cerebrovascular health and unraveling age-related mechanisms involved in ischemic strokes.