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[IEEE 2018 25th IEEE International Conference on Image Processing (ICIP) - Athens, Greece (2018.10.7-2018.10.10)] 2018 25th IEEE International Conference on Image Processing (ICIP) - Robust Blood Flow Velocity Estimation from 3D Rotational Angiography
摘要： Blood flow velocity estimation techniques from 2D fluoroscopy and more recently rotational angiography images represent a topic of wide interest in various clinical research areas. In particular, they can be an important step towards patient-specific flow simulations. Additionally, it can be of diagnostic interest to evaluate volumetric blood flow in stenotic vessel segments; e.g. in a patient’s brain. In this work, we present a robust optimization-based approach to estimate mean blood flow velocities from rotational digital subtraction angiography (DSA) images. Our method was extensively evaluated on 70 simulated datasets and 6 clinical datasets with MR phase contrast ground truth data. Our evaluation explores the limitations of image-based velocity estimation; i.e., measurements over short or small vessel segments. Overall, we were able to estimate the mean velocity with average errors as little as 4% for simulation studies, if the vessel segment is sufficiently long, and achieved results within the confines of the MR phase contrast ground truth data for our clinical data, with an average relative error to the centerline measurement of 9.5% ± 10.5%. The achieved accuracy enables patient-specific hemodynamic simulations and may also be of immediate diagnostic interest.
关键词： velocity estimation,flow quantification,contrast medium,angiography
更新于2025-09-09 09:28:46
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[IEEE 2018 24th International Conference on Pattern Recognition (ICPR) - Beijing, China (2018.8.20-2018.8.24)] 2018 24th International Conference on Pattern Recognition (ICPR) - Early Diagnosis of Diabetic Retinopathy in OCTA Images Based on Local Analysis of Retinal Blood Vessels and Foveal Avascular Zone
摘要： This paper introduces a diagnosis system for detecting early signs of diabetic retinopathy (DR) using optical coherence tomography angiography (OCTA) images. We developed a segmentation technique that was able to extract blood vessels from both retinal superficial and deep maps. It is based on a higher order joint Markov-Gibbs random field (MGRF) model, which combines both current and spatial appearance information of retinal blood vessels. To be able to train/test a support vector machine (SVM) classifier, three local features were extracted from the segmented images. These extracted features are the density and appearance of the retinal blood vessels in addition to the distance map of the foveal avascular zone (FAZ). Then, we used SVM with linear kernel to distinguish sub-clinical DR patients from normal cases. By using 105 subjects, the presented computer-aided diagnosis (CAD) system demonstrated an overall accuracy (ACC) of 97.3% and a Dice similarity coefficient (DSC) of 97.9%.
关键词： Markov-Gibbs random field,support vector machine,diabetic retinopathy,optical coherence tomography angiography,computer-aided diagnosis
更新于2025-09-09 09:28:46
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Changes in Ganglion Cell-Inner Plexiform Layer Thickness and Retinal Microvasculature in Hypertension: An OCT Angiography Study
摘要： Objective: To investigate retinal blood flow in patients with hypertension using optical coherence tomography angiography (OCTA) and the relationship between blood flow metrics and ganglion cell-inner plexiform layer (GC-IPL) thickness. Design: Retrospective, cross-sectional study. Methods: A total of 201 eyes from 117 healthy subjects and 84 hypertensive patients without any ocular abnormalities were included. Hypertensive patients were divided into the two groups according to disease periods (<5 years: hypertension group 1; ≥5 years: hypertension group 2). Macular 3 × 3 mm angiography was acquired using the Zeiss Cirrus 5000 OCT instrument. Vessel density (VD), perfusion density (PD), and foveal avascular zone metrics of the superficial capillary plexus were automatically calculated, and the thicknesses of the central fovea, GC-IPL, and peripapillary retinal nerve fiber layer (RNFL) were measured. All measurements were compared among the three groups, and retinal blood flow metrics were correlated with the thickness of each retinal layer. Logistic regression analyses were performed to determine the factors associated with prolonged hypertension. Results: The average GC-IPL (p<0.001) and peripapillary RNFL (p=0.048) thicknesses in hypertension group 2 were significantly thinner compared to the control group. The 3 mm total area of the VD and PD was also decreased compared to the control group and hypertension group 1 (all p<0.05), and was significantly correlated with the GC-IPL (VD: r=0.450, p=0.001; PD: r=0.467, p<0.001) and peripapillary RNFL (VD: r=0.314, p=0.027; PD: r=0.328, p=0.023) thicknesses in hypertension group 2. Using multivariate logistic analyses, only the average GC-IPL thickness was a significant factor for prolonged hypertension (odds ratio=0.911, p=0.002). Conclusions: In patients with hypertension lasting more than 5 years, inner retinal layer thinning, particularly GC-IPL thinning, was observed, which was significantly correlated with a decrease in retinal blood flow. Therefore, physicians should consider the effects of hypertension on the GC-IPL.
关键词： hypertension,retinal microcirculation,optical coherence tomography angiography,ganglion cell-inner plexiform layer
更新于2025-09-09 09:28:46
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Optical Coherence Tomography Angiography in Familial Exudative Vitreoretinopathy: Clinical Features and Phenotype-Genotype Correlation
摘要： PURPOSE. To evaluate the microstructure of the fovea in patients with familial exudative vitreoretinopathy (FEVR) compared to healthy controls using optical coherence tomography angiography (OCTA). METHODS. In this consecutive, cross-sectional, observational case series, 41 eyes of 41 patients diagnosed as FEVR and 37 eyes in 37 control subjects were studied. OCTA was utilized to automatically measure the foveal avascular zone (FAZ) and the vessel density (VD). Inner retinal thicknesses (IRT) and central retinal thickness (CRT) were measured with the instrument caliper. Targeted next-generation sequencing was performed, and phenotype-genotype association was analyzed. RESULTS. Small FAZ was found in 31.70% (13/41) FEVR eyes but not in controls. Greater CRT and lower super?cial foveal VD were noted in FEVR patients. FAZ is negatively correlated with IRT. Persistence of the inner retinal layer (IRL) in fovea was present in 48.78% (20/41) FEVR eyes but not found in controls. Zero percent (0/10) of patients with the low-density lipoprotein receptor-related protein 5 (LRP5) mutation, 50% (1/2) with the frizzled-4 (FZD4) mutation, and 66.67% (3/4) with the tetraspanin-12 (TSPAN12) mutation had preserved foveal IRL and small FAZ. CONCLUSIONS. Our data indicate FEVR status is associated with a signi?cantly smaller FAZ, decreased vascular density in both the super?cial and deep layers of parafoveal area, a thicker fovea, and an abnormally preserved IRL in fovea. In addition, patients with the LRP5 mutation had a milder phenotype than those with the FDZ4 or TSPAN12 mutations. These novel ?ndings could provide insight into the understanding of the pathogenesis of FEVR.
关键词： phenotype-genotype correlation,optical coherence tomography angiography,familial exudative vitreoretinopathy
更新于2025-09-09 09:28:46
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Interaction driven enhancement of depth perception in angiographic volumes
摘要： User interaction has the potential to greatly facilitate the exploration and understanding of 3D medical images for diagnosis and treatment. However, in certain specialized environments such as in an operating room (OR), technical and physical constraints such as the need to enforce strict sterility rules, make interaction challenging. In this paper, we propose to facilitate the intraoperative exploration of angiographic volumes by leveraging the motion of a tracked surgical pointer, a tool that is already manipulated by the surgeon when using a navigation system in the OR. We designed and implemented three interactive rendering techniques based on this principle. The benefit of each of these techniques is compared to its non-interactive counterpart in a psychophysics experiment where 20 medical imaging experts were asked to perform a reaching/targeting task while visualizing a 3D volume of angiographic data. The study showed a significant improvement of the appreciation of local vascular structure when using dynamic techniques, while not having a negative impact on the appreciation of the global structure and only a marginal impact on the execution speed. A qualitative evaluation of the different techniques showed a preference for dynamic chroma-depth in accordance with the objective metrics but a discrepancy between objective and subjective measures for dynamic aerial perspective and shading.
关键词： Depth cues,Angiography,Evaluation,Interaction techniques,Volume visualization,Image-guided surgery
更新于2025-09-09 09:28:46
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Peripheral Vascular Leakage Findings of Asymptomatic Eyes Based on Fluorescein Angiography
摘要： Purpose: To report peripheral vascular retinal leakage findings of asymptomatic eyes based on fluorescein angiography, and investigate the associated factors. Methods: Data were collected retrospectively from 47 subjects (94 eyes) and the peripheral leakage results based on fluorescein angiography were analyzed. The relationship between peripheral leakage findings and other factors including- arm-retinal circulation time (ARCT) and venous filling time (VFT), refractive error, age, hypertension, and diabetes- was evaluated. Results: Ten eyes had peripheral leakage (21.3%). The mean age was 34.7 ± 7.86 years in the non-leakage group and 44.3 ± 9.63 years in the leakage group; the difference between the groups was statistically significant (p = 0.001). The mean spherical equivalent was -2.85 ± 2.71 diopter in the non-leakage group and -3.46 ± 3.62 diopter in the leakage group; the difference between the groups were not significant (p = 0.471). The mean ARCT was 10.50 ± 2.06 seconds in the non-leakage group and 11.76 ± 2.47 seconds in the leakage group; the difference between the groups was statistically significant (p = 0.041). The mean VFT was 9.70 ± 1.91 seconds in the non-leakage group and 10.75 ± 1.40 seconds in the leakage group; the difference between the groups was statistically significant (p = 0.048). Conclusions: Peripheral leakage can be found in asymptomatic eyes. Age, VFT, and ARCT were correlated to peripheral leakage findings based on angiography. These leakage findings were thought to be related with histological properties and physiological changes in peripheral retina.
关键词： Arm-retinal circulation time,Peripheral leakage,Fluorescein angiography,Venous filling time
更新于2025-09-09 09:28:46
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Analysis of Foveal Microvascular Structures Using Optical Coherence Tomography Angiography in Age-stratified Healthy Koreans
摘要： Purpose: To evaluate foveal avascular zone (FAZ) microvascular structural changes in healthy Korean subjects stratified by age using optical coherence tomography angiography (OCTA). Methods: Eighty eyes of 43 healthy volunteer subjects who had 20/20 or better best corrected visual acuity without other ocular or systemic disease except vitreous floaters and dry eye syndrome were enrolled and stratified by age group. To measure FAZ size and vascular density (VD) of the superficial capillary plexus (SCP) and deep capillary plexus (DCP), OCTA (DRI OCT Triton, Swept Source OCT, Topcon, Tokyo, Japan) scans were performed over fovea-centered 3 × 3 mm2 regions, and then compared with central macular thickness (CMT) and subfoveal choroidal thickness. Results: Mean age of the participants was 46.4 ± 16.1 (20–78). The SCP and DCP FAZ sizes were 0.32 ± 0.11 mm2 and 0.41 ± 0.14 mm2, respectively. There was a significant difference by age group (p < 0.001, p < 0.001), respectively. The FAZ VD for SCP and DCP was 28.96 ± 3.05% and 33.15 ± 3.64%, respectively. There was no difference between age groups (p = 0.118, p = 0.637). Univariate and multiple linear regression analysis showed that the FAZ size of SCP and DCP was significantly correlated with age (p = 0.039, p = 0.002) and CMT (p = 0.007, p = 0.013), respectively. The SCP and DCP FAZ size were positively correlated with age (R2 = 0.279, p < 0.001, R2 = 0.344, p < 0.001), and negatively correlated with CMT (R2 = 0.354, p < 0.001, R2 = 0.285, p < 0.001), respectively. Conclusions: The FAZ size of SCP and DCP increased with age and were negatively correlated with CMT. These results suggest that consideration of age and CMT is important when performing the clinical evaluation of FAZ size in healthy subjects.
关键词： Healthy subjects,Foveal avascular zone,Vascular density,Age,Optical coherence tomography angiography
更新于2025-09-09 09:28:46
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Imaging Parameter Optimization of 3D Phase Contrast-MRA to Reduce Susceptibility-artifact and Radiofrequency-shielding around the Intracranial Stent; 頭蓋内ステントに発生する磁化率およびRF 遮断効果によるアーチファクトを低減するための3D phase contrast MRA の撮像条件の検討;
摘要： The purpose of this study was to evaluate the degree of signal attenuation generated around the stent by the susceptibility artifacts and radiofrequency (RF) shielding in phase contrast-magnetic resonance angiography (PCA) images and construct optimal PCA imaging parameters for intracranial stent lumen images. The two types of PCA images of stents (Neuroform, Enterpraise II) placed in the vascular flow phantom were imaged with different the flip angle (FA) and echo time (TE). Each original image of the vascular flow phantom was reconstructed into a coronal multiplanar reconstruction (MPR) image and a profile curve along the long axis of the stent was calculated. The reduction of in-stent signal was assessed by relative in-stent signal (RIS) calculated by comparing intra-stent signal intensity to the reference tube in the original images. When the TE was 2.3ms, the profile curve was the highest signal intensity. However, RIS had not changed by the extension of TE. When the FA was high, the RIS showed a high value, but when it exceeded 25 degrees, the signal attenuated in the distal part of the slab. The susceptibility artifacts and RF shielding generated around the stent can be reduced by the shortest TbE (2.3ms) and 20 degrees of FA in the PCA imaging.
关键词： susceptibility artifact,radiofrequency (RF) shielding,magnetic resonance angiography (MRA),stent,phase contrast
更新于2025-09-09 09:28:46
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Repeatability and Reproducibility of Quantification of Superficial Peri-papillary Capillaries by four Different Optical Coherence Tomography Angiography Devices
摘要： This study was performed to test the repeatability and reproducibility of measurements of peri-papillary capillaries from four optical coherence tomography angiography (OCTA) devices. 109 healthy eyes were imaged with four OCTA devices (Spectralis, Optovue, Triton and Cirrus). A 3 × 3 mm scan pattern centered on the disc was repeated twice by each device. En face images of superficial capillary plexus were screened and processed for calculation. Vessel length density (VLD) was calculated on four equally divided parts of a ring between two concentric circles manually centered on the disc. General linear model (GLM) was used to test the impact of device and location on VLD. Intraclass correlation coefficient (ICC) of VLD between repeated scans was calculated. Of 218 acquisitions, 36%, 92%, 76% and 88% were eligible for analysis from Spectralis, Optovue, Triton and Cirrus, respectively. ICC was 0.94, 0.90, 0.84 and 0.87 for the four devices. GLM showed measurements significantly varied among devices (P < 0.001) and locations (P < 0.001). Pairwise comparison showed Triton = Spectralis >Optovue >Cirrus, and temporal = nasal >superior = inferior in measuring capillary VLD. This study revealed the repeatability of measuring peri-papillary capillaries was high for all four devices, while the reproducibility among the machines was unfavorable.
关键词： optical coherence tomography angiography,vessel length density,peri-papillary capillaries,reproducibility,repeatability
更新于2025-09-09 09:28:46
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Abnormal choroidal flow on optical coherence tomography angiography in central serous chorioretinopathy
摘要： Importance: Analyzing choroidal flow in central serous chorioretinopathy (CSC) with novel device Background: To examine the abnormal morphology of choriocapillary flow with optical coherence tomography angiography (OCTA) according to the presence of subretinal fluid (SRF) in CSC. Design: A hospital-based retrospective study Participants: We analyzed OCTA results of 68 eyes (68 patients) diagnosed as CSC with or without SRF (active and resolved CSC, respectively) at the Asan Medical Center. Methods: We classified OCTA choriocapillary images into three pattern groups: mixed perfusion, hyper-perfusion, and normal perfusion. Data analysis included age, follow-up duration, treatment modalities, number of treatments, subfoveal choroidal thickness, and SRF height. Main outcome measure: The relationship between CSC activity and choriocapillary pattern Results: Abnormal choroidal flow (mixed and hyper-perfusion) was more frequently found in eyes with active CSC (100%) than resolved CSC (47.5%, p < 0.001). In active CSC eyes, mixed perfusion was predominant (71.4%), while hyper-perfusion was predominant in those with resolved CSC (73.7%). Eyes with recently resolved CSC (SRF absorption present for <2 months) had abnormal choriocapillary flow more often than the remaining eyes with resolved CSC (83.3% vs. 32.1%, p = 0.005). Resolved CSC eyes with abnormal choriocapillary flow demonstrated more recurrence than eyes with normal choriocapillary flow (42.1% vs 9.5%, p = 0.017). Conclusions and Relevance: The pattern of choriocapillary flow abnormalities on OCTA can indicate CSC disease activity. Because eyes with resolved CSC showing abnormal choroidal flow have a high recurrence rate, they should be carefully followed-up.
关键词： Abnormal choroidal flow,central serous chorioretinopathy,optical coherence tomography angiography
更新于2025-09-09 09:28:46