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- 2015
- cardiovascular imaging
- coronary artery disease
- coronary calcium score
- atherosclerosis
- coronary CT angiography.
- Medical Imaging
- Università degli Studi di Napoli Federico II
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Response of Inner Retinal Oxygen Extraction Fraction to Light Flicker Under Normoxia and Hypoxia in Rat
摘要： PURPOSE. Oxygen extraction fraction (OEF), defined by the ratio of oxygen metabolism (MO2) to delivery (DO2), determines the level of compensation of MO2 by DO2. In the current study, we tested the hypothesis that inner retinal OEF remains unchanged during light flicker under systemic normoxia and hypoxia in rats due to the matching of MO2 and DO2. METHODS. Retinal vascular oxygen tension (PO2) measurements were obtained in 10 rats by phosphorescence lifetime imaging. Inner retinal OEF was derived from vascular PO2 based on Fick's principle. Measurements were obtained before and during light flicker under systemic normoxia and hypoxia. The effects of light flicker and systemic oxygenation on retinal vascular PO2 and OEF were determined by ANOVA. RESULTS. During light flicker, retinal venous PO2 decreased (P < 0.01, N = 10), while inner retinal OEF increased (P = 0.02). Under hypoxia, retinal arterial and venous PO2 decreased (P < 0.01), while OEF increased (P < 0.01). The interaction effect was not significant on OEF (P = 0.52), indicating the responses of OEF to light flicker were similar under normoxia and hypoxia. During light flicker, OEF increased from 0.46 ± 0.13 to 0.50 ± 0.11 under normoxia, while under hypoxia, OEF increased from 0.67 ± 0.16 to 0.74 ± 0.14. CONCLUSIONS. Inner retinal OEF increased during light flicker, indicating the relative change in DO2 is less than that in MO2 in rats under systemic normoxia and hypoxia. Inner retinal OEF is a potentially useful parameter for assessment of the relative changes of MO2 and DO2 under physiologic and pathologic conditions.
关键词： vascular oxygen tension,retina,oxygen extraction fraction,hypoxia,light flicker
更新于2025-09-23 15:22:29
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3D surface reconstruction of retinal vascular structures
摘要： We propose in this paper, a three-dimensional surface reconstruction of a retinal vascular network from a pair of 2D retinal images. Our approach attempts to address the above challenges by incorporating an epipolar geometry estimation and adaptive surface modelling in a 3D reconstruction, using three steps: segmentation, 3D skeleton reconstruction and 3D surface modelling of vascular structures. The intrinsic calibration matrices are found via the solution of simplified Kruppa equations. A simple essential matrix based on a self-calibration method has been used for the ‘fundus camera-eye’ system. The used method has eventually produced vessel surfaces that could be fit for various applications, such as applications for computational fluid dynamics simulations and applications for real-time virtual interventional.
关键词： Kruppa equations,curvature-dependent subdivision,surface reconstruction,epipolar geometry,segmentation,retinal vascular network,self-calibration
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE International Conference on Imaging Systems and Techniques (IST) - Krakow, Poland (2018.10.16-2018.10.18)] 2018 IEEE International Conference on Imaging Systems and Techniques (IST) - A Novel MRA-Based Framework For Detecting Correlation Between Cerebrovascular Changes and Mean Arterial Pressure
摘要： Systemic hypertension is a signi?cant contributor for strokes and cognitive impairment and is a leading cause of mortality in the USA. Changes in cerebral vascular diameter and cerebral perfusion pressure have been reported to precede elevation of systemic blood pressures. A novel, non-invasive Time-of-Flight - Magnetic Resonance Angiography (TOF-MRA) based framework for detection of cerebrovascular changes is presented. The proposed framework analyzes brain TOF-MRA data to quantify changes in cerebral vascular diameter and cerebral perfusion pressure. The framework has three major steps: 1) Adaptive segmentation to extract large and small diameter cerebral vessels from TOF-MRA images using both appearance and 3-D spatial information of the vascular system; 2) Estimation of the Cumulative Distribution Function (CDF) of the 3-D distance map of the cerebral vascular system, which represents the changes in diameter of the 3-D vascular system ; and 3) Statistical and correlation analysis that measured the effect of Mean Arterial Pressure (MAP) on blood vessels’ diameter changes. The ef?cacy of the framework was evaluated using MRA images and blood pressure (BP) measurements obtained from 15 patients (M=8, F=7, Age=49.2±7.3 years) on Day 0 and Day 700. The framework had a dice similarity coef?cient of 92.23%, a sensitivity of 94.8% and a speci?city of ～ 99% in detecting elevated vascular pressures compared to ground truth. Statistical analysis demonstrated an inverse relationship between blood vessels diameters and MAP. This correlation was valid for both upper (above the circle of Willis) and lower (circle of Willis and below) sections of the brain. The proposed methodology may be used to quantify changes in cerebral vasculature and cerebral perfusion pressure non-invasively through MRA image analysis, which may be a useful tool for clinicians to optimize medical management of pre-hypertension and hypertension.
关键词： Vessel Diameter,Skull Stripping,CDF,Automatic Segmentation,Mean Arterial Pressure,Blood Vessels,MRA,Hypertension,Median Vascular Radius
更新于2025-09-23 15:22:29
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Efficacy of aflibercept on exudative age-related macular degeneration in patients exhibiting complete ranibizumab resistance and tachyphylaxis
摘要： Purpose: The present study compared the efficacy of aflibercept for neovascular age-related macular degeneration (NV-AMD) in patients with complete ranibizumab resistance and tachyphylaxis. Methods: Forty-four eyes of 38 neovascular age-related macular degeneration patients were evaluated. Eyes were divided into a complete resistance group (n=23 eyes) and tachyphylaxis group (n=21 eyes). Results: After three injections, eight (38.1%) patients in the tachyphylaxis group and nine (39.1%) in the complete resistance group presented with macular dryness. After the first injection of aflibercept, the mean visual acuity improved significantly in the tachyphylaxis group (p=0.018) but remained unchanged in the complete resistance group (p=0.37). There was a non-significant trend towards improved mean visual acuity in both groups after the second and third injections relative to the acuity at the final visit for ranibizumab treatment. In the tachyphylaxis group, the presence of subfoveal pigmented epithelium detachment (PED) decreased significantly after intravitreal aflibercept treatment. Conclusions: Although treatment with aflibercept yielded generally positive anatomical results in both groups, no significant increase in visual acuity was achieved.
关键词： Tachyphylaxis,Ranibizumab,Angiogenesis inhibitors,Vascular endothelial growth factor A,Macular degeneration
更新于2025-09-23 15:21:21
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MicroRNA-9 inhibits retinal neovascularization in rats with diabetic retinopathy by targeting vascular endothelial growth factor A
摘要： Diabetic retinopathy (DR) is a leading cause of adult visual impairment and loss. This study aims to explore the effects of microRNA‐9 (miR‐9) on retinal neovascularization during DR by targeting the vascular endothelial growth factor A (VEGFA). DR rat models were successfully established. Retinal microvascular endothelial cells (RMECs) of DR rats were isolated and treated with miR‐9 mimic, miR‐9 inhibitor or small interfering RNA (siRNA)‐VEGFA. The expressions of miR‐9, VEGFA, and cluster of differentiation 31 (CD31) of the rats’ tissues and cells were examined. The targeting relationship between miR‐9 and VEGFA was testified. The tubule formation, the cell proliferation and the periodic distribution and apoptosis were evaluated after transfection. In the retinal tissues of DR rats, miR‐9 expression decreased while the expression of VEGFA and CD31 increased. Notably, miR‐9 targeted and inhibited VEGFA expression. In response to the treatment of miR‐9 mimic and siRNA‐VEGFA, a reduction was identified in CD31 expression, tubule formation, and proliferation of RMECs and cell ratio in the S phase, but an increase was observed in apoptosis rate of RMECs. The treatment of miR‐9 inhibitor reversed the manifestations. Our study demonstrated that miR‐9 could inhibit retinal neovascularization of DR and tubule formation, and promote apoptosis in RMECs by targeting VEGFA.
关键词： retinal microvascular endothelial cells,diabetic retinopathy,vascular endothelial growth factor A,microRNA‐9,retinal neovascularization
更新于2025-09-23 15:21:21
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High-Resolution Shortwave Infrared Imaging of Vascular Disorders Using Gold Nanoclusters
摘要： We synthesized a generation of water-soluble, atomically precise gold nanoclusters (Au NCs) with anisotropic surface containing short dithiol pegylated chain (AuMHA/TDT). These AuMHA/TDT exhibit a high brightness (QY～6%) in the shortwave infrared (SWIR) spectrum with a detection above 1250 nm. Furthermore, they show an extended half-life in blood (t1/2? = 19.54 ±0.05 h) and a very weak accumulation in organs. We also developed a non-invasive, whole-body vascular imaging system in the SWIR window with high-resolution, benefiting from a series of Monte Carlo image processing of the images. The imaging process enabled to improve contrast by one order of magnitude and enhance by 59% the spatial resolution. After systemic administration of these nanoprobes in mice, we can quantify vessel complexity in depth (> 4 mm) allowing to detect very subtle vascular disorders non-invasively in bone morphogenetic 9 (Bmp9) deficient mice. The combination of these anisotropic surface charged gold nanoclusters plus an improved SWIR imaging device allows then a precise mapping at high resolution and in depth of the organization of the vascular network in live animals.
关键词： shortwave infrared fluorescence,bone morphogenetic 9 (Bmp9),gold nanoclusters,vascular disorder,monte carlo restoration imaging processing
更新于2025-09-23 15:21:01
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The efficacy and safety of a 577a??nm higha??power optically pumped semiconductor laser in the treatment of postacne erythema
摘要： Background: Postacne erythema (PAE) is a common sequela of inflammatory acne vulgaris. Treatment of which has been challenging due to limited options available and the variability of results for each modality. Recently, a 577-nm high-power optically pumped semiconductor laser (HOPSL) initially developed for vascular lesions, has shown promising results for the treatment of PAE. Objective: To evaluate the efficacy and safety of 577-nm HOPSL in the treatment of postacne erythema. Materials and Methods: This was a split-face, randomized controlled trial pilot study. Twenty-one patients with PAE on both sides of their face were enrolled. Each subject’s face sides were randomly assigned to either receive 577-nm HOPSL treatment (QuadroStar PROTM, Asclepion Laser Technologies, Jena, Germany) using the scanner handpiece, 1mm spot size, 80% coverage, 12-15 J/cm2, 30 ms, 2 passes for 3 sessions at 1-month intervals, or no treatment at all. Outcome measures such as overall improvement, the Erythema Index (EI) and Melanin Index (MI) from 3 different areas on both treatment and control sides were assessed at baseline, and 1-month follow-up after each treatment session. Side effects including pain, erythema, swelling, and crusting were also recorded. Results: Upon completion of the treatment period, the mean EI was significantly decreased in both treated and non-treated sides of the face (p<0.001 and p=0.001, respectively). The laser-treated sides already demonstrated significant reduction in the mean EI compared to non-treated sides at 1 month after the 2nd treatment (p=0.007). The mean MI of both sides; however, did not show any statistically significant differences from baseline, and likewise when comparing between sides. Patients reported more improvement on laser-treated sides compared to non-treated sides. Reported side effects were limited to mild discomfort during treatment and transient facial erythema lasting approximately 30 minutes. Conclusion: Patients who received treatment with the 577-nm HOPSL had better outcomes with minimal side effects at 1 month after 2 treatments as compared to those who did not receive any treatment. Therefore, the 577-nm HOPSL may be considered as an effective adjuvant treatment for PAE and early erythematous atrophic scars.
关键词： Vascular-specific laser,577-nm high-power optically pumped semiconductor laser (HOPSL),Postacne erythema
更新于2025-09-23 15:21:01
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Validating a low-cost laser speckle contrast imaging system as a quantitative tool for assessing retinal vascular function
摘要： The ability to monitor progression of retinal vascular diseases like diabetic retinopathy in small animal models is often complicated by their failure to develop the end-stage complications which characterize the human phenotypes in disease. Interestingly, as micro-vascular dysfunction typically precedes the onset of retinal vascular and even some neurodegenerative diseases, the ability to visualize and quantify hemodynamic changes (e.g. decreased flow or occlusion) in retinal vessels may serve as a useful diagnostic indicator of disease progression and as a therapeutic outcome measure in response to treatment. Nevertheless, the ability to precisely and accurately quantify retinal hemodynamics remains an unmet challenge in ophthalmic research. Herein we demonstrate the ability to modify a commercial fundus camera into a low-cost laser speckle contrast imaging (LSCI) system for contrast-free and non-invasive quantification of relative changes to retinal hemodynamics over a wide field-of-view in a rodent model.
关键词： ophthalmic research,laser speckle contrast imaging,retinal hemodynamics,retinal vascular diseases,diabetic retinopathy
更新于2025-09-23 15:21:01
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Retinal vascular changes and aqueous humor cytokines changes after aflibercept intravitreal injection in treatment-na?ve myopic choroidal neovascularization
摘要： The aim of the study was to assess retinal vascular changes using optical coherence tomography angiography (OCTA) and aqueous humour changes of vascular endothelial growth factor (VEGF) and placental growth factor (PIGF) levels in treatment-na?ve myopic choroidal neovascularization (mCNV) after aflibercept intravitreal injection. To explore the correlation between clinical and laboratory parameters. Fifteen eyes of 15 patients with treatment-na?ve mCNV underwent 2 intravitreal injections of aflibercept. Main outcome measures were best corrected visual acuity (BCVA), central retinal thickness (CRT) and external limiting membrane (ELM) visualization at OCT, lesion area and leakage at fluorescein angiography (FA), OCTA flow area and selected area at baseline and after the injections. Analysis of VEGF and PlGF in the aqueous humor was performed before each injection in cases and prior to cataract surgery on 10 patients as included as controls. Median BCVA increased from 0.6 to 0.3 logMAR (p < 0.001); CRT decreased from 387.5 to 267 micron (p < 0.001); FA area from 0.8 to 0.5 mm2 and OCTA area from 0.9 to 0.5 mm2 (p = 0.005). PIGF values changed from 1.8 to 1.4 pg/ml (p = 0.019) and VEGF values from 3.4 to 0.5 pg/ml (p = 0.008). A significant correlation was found after treatment between PIGF levels and BCVA (rho = 0.006) and VEGF levels and BCVA (rho = 0.018); between PlGF and CRT (rho = 0.020), PlGF and ELM visualization (rho = 0.002) and PlGF and FA leakage (rho < 0.001). Our results showed a significant reduction of mCNV area after aflibercept in both FA and OCTA measurements; an improvement of BCVA, and a reduction of VEGF and PIGF levels related to inactivity of the disease.
关键词： retinal vascular changes,OCTA,PlGF,myopic choroidal neovascularization,intravitreal injection,aflibercept,VEGF,aqueous humor cytokines
更新于2025-09-23 15:21:01
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[ACM Press the 2nd International Conference - Taipei, Taiwan (2018.08.13-2018.08.15)] Proceedings of the 2nd International Conference on E-Society, E-Education and E-Technology - ICSET 2018 - Detecting Four-Limb Blood Oxygen Saturation and Heart Rate based on Reflex Photoplethysmography
摘要： The study purpose is to construct a reflective Oxygen Saturation (SpO2) and Heart Rate (HR) four-limb detective device, improve transmission SpO2 device only to measure finger, toe and earlobe. Using Silicon Labs Si1143, Arduino Nano, self-calibrated SpO2 algorithm and mobile application software constitute a mobile reflective SpO2 and HR detective device. Static four parts and post-exercise experiment had been carried out to test our device, the result can achieve comparable performance to a clinical device with no significant difference revealed by paired t-tests. This study has applied for clinical trial permission, the schedule will improve the calibration curve and compensation factor of unverifiable body parts by blood draw comparison. Provide clinical staff for immediate local SpO2 and HR information, evaluate the effectiveness of vascular suture and hyperbaric oxygen therapy.
关键词： Photoplethysmography,Oxygen Saturation,Heart Rate,Vascular suture,Hyperbaric Oxygen Therapy,Four-Limb
更新于2025-09-23 15:21:01