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Efficacy of navigated focal laser photocoagulation in diabetic macular edema planned with en face optical coherence tomography versus fluorescein angiography
摘要： Aim To analyze the efficacy of navigated focal laser photocoagulation (FLP) of microaneurysms in diabetic macular edema (DME) planned using en face optical coherence tomography (OCT) as against fluorescein angiography (FA). Methods Twenty-six eyes of 21 DME patients (12 males, 9 females, 69.5 ± 12.3 years) with mean BCVA of 0.52 ± 0.44 LogMAR were included. En face OCT images of deep capillary plexus slab and FA images were used to plan FLP targeting of leaky microaneurysms. The primary outcome measures were central retinal thickness (CRT) and macular volume. The secondary outcome measure was best-corrected visual acuity (BCVA). Results The difference in the change of CRT and macular volume between en face OCT and FA-planned FLP after 1 month and at the end of follow-up was not statistically significant (p > 0.05), except for a higher CRT reduction in the en face OCT-planning group (p = 0.007) at the end of mean follow-up of 2.6 ± 0.9 months. There was no difference in BCVA change between the two planning options (p = 0.42). Conclusion En face OCT is a non-inferior alternative for FA in the planning of navigated FLP of microaneurysms in DME.
关键词： Navigated laser,Optical coherence tomography,Diabetic macular edema,Focal laser photocoagulation,Optical coherence tomography angiography,Fluorescein angiography,Microaneurysms
更新于2025-09-23 15:19:57
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Microvascular changes in macula and optic nerve head after femtosecond laser-assisted LASIK: an optical coherence tomography angiography study
摘要： To measure the microcirculation change of macula and optic nerve head before and after femtosecond laser assisted laser in situ keratomileusis. In total 45 eyes from 45 subjects, who underwent FS-LASIK during June 2017 to December 2017 in Guangdong Provincial People’s Hospital, were recruited in this study. Vessel density in macula and optic nerve head were measured by optical coherence tomography angiography before and after transient elevation in intraocular pressure caused by application of suction ring during surgery. Vessel density (VD) at superficial (SCP) plexus of macular region did not differ after surgery (F(3,132) = 1.41, P = 0.24), while the deep (DCP) plexus of macular region significantly decreased 1 day after surgery (P = 0.001) but returned to its baseline value 1 month postoperatively (P = 0.1). Vessel density of optic nerve head region had no significant changes after surgery (F(2.51,95.18) = 0.6, P = 0.59). A short-term temporary decrease of vessel density at deep layer of macular region was observed in eyes undergoing FS-LASIK. However, the retinal capillary density went back to preoperative level 1 month after surgery. Therefore, transient IOP spike during FS-LASIK did not cause long-term decline of retinal microcirculation.
关键词： Optical coherence tomography angiography,Femtosecond laser-assisted LASIK,Microvascular changes,Macula,Optic nerve head
更新于2025-09-23 15:19:57
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Fast and efficient detection of 511 keV photons using Cherenkov light in PbF <sub/>2</sub> crystal, coupled to a MCP-PMT and SAMPIC digitization module
摘要： We study the possibility to use the Cherenkov light for the e?cient detection of 511 keV photons with the goal to use it in TOF-PET. We designed and tested two detection modules consisting of PbF2 crystals attached to Planacon MCP-PMT XP85012. Ampli?ed PMT signals are digitized by the SAMPIC module with high readout rate, up to 105 events/s, and a negligible contribution to the time resolution, below 20 ps (FWHM). We developed a fast 2D scanning system to calibrate the PMT time response and studied in details the timing characteristics of the Planacon PMT. Using a radioactive 22Na source we measured a detection e?ciency of 24% for 511 keV photons in a 10 mm thick crystal and a coincidence resolving time of 280 ps. We analyzed the main factors limiting the time resolution of the large-surface detection module and proposed solutions to improve it, which will be tested in our future project.
关键词： Photon detectors for UV, visible and IR photons (vacuum) (photomultipliers, HPDs, others),Cherenkov and transition radiation,Gamma camera, SPECT, PET PET/CT, coronary CT angiography (CTA)
更新于2025-09-23 15:19:57
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Future clinical applicability of optical coherence tomography angiography
摘要： Optical coherence tomography angiography (OCT-A) is an emerging technology that allows for the non-invasive imaging of the ocular microvasculature. Despite the wealth of observations and numerous research studies illustrating the potential clinical uses of OCT-A, this technique is currently rarely used in routine clinical settings. In this review, technical and clinical aspects of OCT-A imaging are discussed, and the future clinical potential of OCT-A is considered. An understanding of the basic principles and limitations of OCT-A technology will better inform clinicians of its future potential in the diagnosis and management of ocular diseases.
关键词： ocular microvasculature,corneal vascularisation image artifact,segmentation,optical coherence tomography angiography,optic nerve head disease,algorithm,retinal disease
更新于2025-09-23 15:19:57
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Do microvascular changes occur preceding neural impairment in early-stage diabetic retinopathy? Evidence based on the optic nerve head using optical coherence tomography angiography
摘要： Aims To evaluate the microvascular and neural differences of the optic nerve head (ONH) between type 2 diabetes mellitus (T2DM) subjects and controls. Methods This was a cross-sectional observational study. One hundred and eight eyes of 108 T2DM subjects with or without diabetic retinopathy (DR) (54 preclinical DR and 54 mild-to-moderate DR) were included. Fifty-two eyes of 52 healthy subjects were included as controls. The 4.5-mm Angio Disc scan mode and the ganglion cell complex scan mode were performed with all participants using AngioVue software 2.0 of the optical coherence tomography angiography (OCTA) device. Results Regarding ONH radial peripapillary capillary (RPC) density, the peripapillary region was mainly significantly reduced in the No-DR (NDR) group. Moreover, the RPC density of the peripapillary region and the inside optic disc area were significantly reduced in the non-proliferative DR (NPDR) group. When compared to the controls, significantly reduced peripapillary capillary density in six sections was observed in the NPDR group. However, reduced density was observed in only two sections in the NDR group. The NPDR group had significantly increased focal loss volume (FLV) and reduced peripapillary RNFL thickness in the inferior nasal section compared to those in the controls, but similar changes were not observed in the NDR group. A regression model identified RPCs inside the optic disc as a significant parameter in early-stage DR detection. In the NPDR group, BCVA showed a significantly negative correlation with RPCs inside the optic disc and a significantly positive correlation with FLV. Conclusions OCTA findings of the ONH area may provide evidence that microvascular changes occur preceding neural impairment in early-stage DR. However, further researches are still needed to support the statement. Reduced ONH perfusion inside the optic disc may be one of the crucial biomarkers in early-stage DR detection and is a possible sensitive visual acuity predictor in early-stage DR subjects. With the ONH mode, OCTA may be a more promising tool in DR screening.
关键词： Neural impairment,Optical coherence tomography angiography,Optic nerve head,Microvascular changes,Diabetic retinopathy
更新于2025-09-19 17:15:36
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Feasible scan timing for 320-row coronary CT angiography generated by the time to peak in the ascending aorta
摘要： Purpose: A 320-row CT scanner can briefly scan the entire heart. Therefore, the feasible scan timing is required. The aim of this study was to propose a refined method for feasible scan timing for coronary CT angiography (CCTA) using a time-density curve of the ascending aorta (AAo). Methods: One-hundred and twenty-nine patients were prospectively enrolled. All patients were performed test-bolus method. For the initial 65 patients, the scan timing was determined as a 3.0 s delay at the peak time in the AAo, which was defined as the conventional protocol (COV-P). For the next 64 patients, a scan timing of 1.0, 3.0, or 5.0 s delay was determined according to the interval from the contrast media arrival to peak time in the AAo, which was defined as the arrival to peak protocol (AP-P). The optimal scan timing was identified by the measurement of CT number in the left atrium, left ventricle, AAo, and descending aorta. The coronary enhancement and heterogeneity were compared between the two protocols. Results: The optimal scan timing was significantly higher in the AP-P than in the COV-P (85.9% vs. 61.5%, p = 0.0017). The CT number in the left circumflex artery (LCX) was significantly higher in the AP-P than the COV-P (344.5 Hounsfield units vs. 316.3 Hounsfield units, p = 0.0484). The heterogeneous index of the LCX was significantly greater for the COV-P than the AP-P (?36.8 vs. –25.8, p = 0.0028). Conclusions: The AP-P can be used to determine the optimal scan timing for CCTA and contributes to stable coronary enhancement.
关键词： Coronary CT angiography,Feasible scan timing,320-row CT
更新于2025-09-19 17:15:36
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Extending the Use of Coronary Calcium Scanning to Clinical Rather Than Just Screening Populations
摘要： Twenty-five years after its initial development, coronary artery calcium (CAC) scanning has become a relatively inexpensive test that has been extensively validated as a potent noninvasive means for assessing the burden of coronary atherosclerosis in asymptomatic individuals. A proportional relationship between the magnitude of CAC abnormality and the frequency of subsequent cardiac events over long-term follow-up has been consistently demonstrated, including observations from large patient and population-based cohorts.1–3 Incremental prognostic value over standard clinical assessments including the Framingham Risk Score and other scores of global risk has also been consistently reported.3,4 Consequently, the application of CAC scanning for assessing asymptomatic patients with intermediate clinical risk has now become part of clinical guidelines.5,6
关键词： tomography, emission-computed, single-photon,myocardial perfusion imaging,coronary angiography,atherosclerosis,Editorials,coronary artery disease
更新于2025-09-19 17:15:36
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The Utility of Frame Averaging for Automated Algorithms in Analyzing Retinal Vascular Biomarkers in AngioVue OCTA
摘要： Purpose: This study proposes an optical coherence tomography angiography (OCTA) frame-averaging method and investigates the effects of the number of frames acquired and averaged on metrics quantifying the foveal avascular zone (FAZ), vessel morphology, and parafoveal intercapillary area (PICA). Methods: Ten OCTA frames were acquired for each of the 19 subjects without known retinal disease using the AngioVue OCTA system. For each subject, acquired frames were ranked by an image quality metric. A subset of frames was then registered and averaged. The effects of the number of frames acquired and averaged on FAZ segmentation and metrics of FAZ geometry, vessel morphology, and PICA were analyzed. Results: Frame averaging increased the accuracy of the automatically segmented FAZ region; for example, the absolute error in FAZ area decreased from 0.026 mm2 (1 frame) to 0.005 mm2 (5 frames). Averaging multiple frames exponentially decreased the estimated number of vessel endpoints and increased the average vessel length with a 32% decrease in number of endpoints and 14% increase in average vessel length when averaging five frames compared with one. Frame averaging also improved the precision of PICA estimates. Conclusions: Averaging multiple OCTA frames using the Optovue AngioVue system reduced error in FAZ segmentation and improved the robustness of OCTA vessel morphology and perfusion metrics. The study demonstrated limited benefit in acquiring and averaging more than five frames. Translational Relevance: Averaging multiple OCTA frames improved the robustness of OCTA foveal biomarkers with limited benefit when averaging more than five frames.
关键词： optical coherence tomography angiography,foveal avascular zone,imaging,averaging
更新于2025-09-19 17:15:36
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Optical coherence tomography angiography and photoacoustic imaging in dermatology
摘要： Optical coherence tomography angiography (OCTA) is a relatively novel functional extension of the widely accepted ophthalmic imaging tool named optical coherence tomography (OCT). Since OCTA’s debut in ophthalmology, researchers have also been trying to expand its translational application into dermatology. The ability of OCTA in resolving microvasculature has shown promising results in imaging skin diseases. Meanwhile, photoacoustic imaging (PAI), which uses laser pulse induced ultrasound waves as the signal, has been studied to differentiate human skin layers and to help skin disease diagnosis. This perspective article gives a short review of OCTA and PAI in the field of photodermatology. After an introduction of the principles of OCTA and PAI, we describe the most updated results of skin disease imaging using these two optical imaging modalities. We also put an emphasis on dual modality imaging combining OCTA and photoacoustic tomography (PAT) for dermatological applications. In the end, the challenges and opportunities of these two imaging modalities in dermatology are discussed.
关键词： microvasculature,dermatology,Optical coherence tomography angiography,photoacoustic imaging,skin imaging
更新于2025-09-19 17:15:36
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Optical coherence tomography angiography monitors human cutaneous wound healing over time
摘要： Background: In vivo imaging of the complex cascade of events known to be pivotal elements in the healing of cutaneous wounds is a difficult but essential task. Current techniques are highly invasive, or lack the level of vascular and structural detail required for accurate evaluation, monitoring and treatment. We aimed to use an advanced optical coherence tomography (OCT)-based angiography (OCTA) technique for the non-invasive, high resolution imaging of cutaneous wound healing. Methods: We used a clinical prototype OCTA to image, identify and track key vascular and structural adaptations known to occur throughout the healing process. Specific vascular parameters, such as diameter and density, were measured to aid our interpretations under a spatiotemporal framework. Results: We identified multiple distinct, yet overlapping stages, hemostasis, inflammation, proliferation, and remodeling, and demonstrated the detailed vascularization and anatomical attributes underlying the multifactorial processes of dermatologic wound healing. Conclusions: OCTA provides an opportunity to both qualitatively and quantitatively assess the vascular response to acute cutaneous damage and in the future, may help to ascertain wound severity and possible healing outcomes; thus, enabling more effective treatment options.
关键词： microvasculature,wound healing,skin,Optical coherence tomography angiography (OCTA)
更新于2025-09-19 17:15:36