Fine Vessels Research Articles

Towards Automated Eye Diagnosis: An Improved Retinal Vessel Segmentation Framework Using Ensemble Block Matching 3D Filter.

Automated detection of vision threatening eye disease based on high resolution retinal fundus images requires accurate segmentation of the blood vessels. In this regard, detection and segmentation of finer vessels, which are obscured by a considerable degree of noise and poor illumination, is particularly challenging. These noises include (systematic) additive noise and multiplicative (speckle) noise, which arise due to various practical limitations of the fundus imaging systems. To address this inherent issue, we present an efficient unsupervised vessel segmentation strategy as a step towards accurate classification of eye diseases from the noisy fundus images. To that end, an ensemble block matching 3D (BM3D) speckle filter is proposed for removal of unwanted noise leading to improved detection. The BM3D-speckle filter, despite its ability to recover finer details (i.e., vessels in fundus images), yields a pattern of checkerboard artifacts in the aftermath of multiplicative (speckle) noise removal. These artifacts are generally ignored in the case of satellite images; however, in the case of fundus images, these artifacts have a degenerating effect on the segmentation or detection of fine vessels. To counter that, an ensemble of BM3D-speckle filter is proposed to suppress these artifacts while further sharpening the recovered vessels. This is subsequently used to devise an improved unsupervised segmentation strategy that can detect fine vessels even in the presence of dominant noise and yields an overall much improved accuracy. Testing was carried out on three publicly available databases namely Structured Analysis of the Retina (STARE), Digital Retinal Images for Vessel Extraction (DRIVE) and CHASE_DB1. We have achieved a sensitivity of 82.88, 81.41 and 82.03 on DRIVE, SATARE, and CHASE_DB1, respectively. The accuracy is also boosted to 95.41, 95.70 and 95.61 on DRIVE, SATARE, and CHASE_DB1, respectively. The performance of the proposed methods on images with pathologies was observed to be more convincing than the performance of similar state-of-the-art methods.

Novel endoscopic ultrasonography imaging technique for visualizing microcirculation without contrast enhancement in subepithelial lesions: Prospective study.

Detective flow imaging for endoscopic ultrasonography (DFI?EUS) is a new imaging modality developed for detecting fine vessels without using ultrasound contrast agents. This study aimed to evaluate its utility by comparing it with a type of directional power Doppler (eFLOW) for subepithelial lesions (SELs). Between January 2019 and January 2020, 28 patients with SELs undergoing DFI?EUS and eFLOW?EUS were enrolled. DFI?EUS and eFLOW?EUS assessing the vascularity in SELs were compared in terms of the rates of identification of intratumoral vessels. We also investigated how large vessels were depicted in both modalities based on surgical specimens as well as the detection rates of intratumoral vessels in gastrointestinal stromal tumors (GISTs) and non?GISTs using either DFI?EUS or eFLOW?EUS. Among 28 patients, 23 with pathological confirmation by EUS?guided fine?needle aspiration biopsy (EUS?FNAB) specimens were included. Of those 23 patients, the 10 who underwent surgical resection were selected for analysis. The rate of detection of intratumoral vessels in SELs was significantly higher on DFI?EUS (80%) than on eFLOW?EUS (30%) (P = 0.03). Comparison with surgical specimens revealed that detection rate for vessels with maximum size of less 1000 μm was higher in DFI?EUS (66%) than that in eFLOW?EUS (0%). GIST patients had significantly higher positive rates (90%) of intratumoral vessels than non?GIST patients (31%) on DFI in 23 cases including EUS?FNAB specimens (P = 0.045). Detective flow imaging?EUS is more sensitive for depicting intratumoral vessels than eFLOW?EUS. Evaluation of intratumoral vessels on DFI?EUS is useful for identifying GISTs without contrast agents.

H-scan Subtraction Doppler Imaging: A Novel Ultrasound Small Blood Vessel Flow Characterization with Scattering and Reflection Identification

Ultrafast compound Doppler imaging (UCDI), which can be used to acquire Doppler information at very high spatial and temporal sampling rates, provides a great improvement to the characterization of the vasculature. The singular value decomposition (SVD) technique takes advantage of the different features of tissue and blood motion in terms of spatiotemporal coherence and strongly outperforms conventional clutter rejection filters in small animals. However, a major challenge of conventional UCDI with SVD clutter filtering for small vessel imaging is that it is not sensitive enough to detect the hemodynamic changes in deep tissue where the majority of the remaining signal is usually noise-saturated. In this study, with the first attempt to apply ultrasonic tissue characterization techniques to UCDI, we propose an H-scan subtraction Doppler imaging method to bypass the limitations associated with the high-order singular value thresholding selection and improve the image quality of fine vessels. The flow phantom experiments with different blood concentrations show that H-Scan is capable of estimating the relative size and spatial distribution of acoustic scattering objects. In the in vivo rabbit brain experiment, the H-Doppler method, together with the global and block-wise local SVD clutter filtering, are proposed to facilitate better power Doppler images with a significant improvement of background noise suppression. These results demonstrate that the contrast-to-noise-ratio (CNR) of the H-scan subtraction Doppler imaging is 15% to 65% higher than that of the conventional UCDI methods. Therefore, this approach can be potentially applied to the clinical applications of the functional ultrasound (fUS) imaging method.

A New Deeply Convolutional Neural Network Architecture for Retinal Blood Vessel Segmentation

This paper proposes an incoming Deep Convolutional Neural Network (CNN) architecture for segmenting retinal blood vessels automatically from fundus images. Automatic segmentation performs a substantial role in computer-aided diagnosis of retinal diseases; it is of considerable significance as eye diseases as well as some other systemic diseases give rise to perceivable pathologic changes. Retinal blood vessel segmentation is challenging because of the excessive changes in the morphology of the vessels on a noisy background. Previous deep learning-based supervised methods suffer from the insufficient use of low-level features which is advantageous in semantic segmentation tasks. The proposed architecture makes use of both high-level features and low-level features to segment retinal blood vessels. The major contribution of the proposed architecture concentrates on two important factors; the first in its supplying of extremely modularized network architecture of aggregated residual connections which enable us to copy the learned layers from the shallower model and developing additional layers to identity mapping. The second is to improve the utilization of computing resources within the network. This is achieved through a skillfully crafted design that allows for increased depth and width of the network while maintaining the stability of its computational budget. Experimental results show the effectiveness of using aggregated residual connections in segmenting retinal vessels more accurately and clearly. Compared to the best existing methods, the proposed method outperformed other existing methods in different measures, comprised less false positives at fine vessels, and caressed more clear lines with sufficient details like the human annotator.

Unsupervised multiscale retinal blood vessel segmentation using fundus images

Blood vessel segmentation is a vital step in automated diagnosis of retinal diseases. Some retinal diseases progress with structural changes in the vessels whereas in others, vessels may remain unaffected. Segmentation of vessels is inevitable in both the cases. The extracted vessel map can be studied for these structural changes or can be removed to highlight other abnormalities of the retina. This study presents a rule-based retinal blood vessel segmentation algorithm. It implements two multi-scale approaches, local directional-wavelet transform and global curvelet transform, together in a novel manner for vessel enhancement and thereby segmentation. The authors have proposed a generic field-of-view mask for extraction of region-of-interest. Further, a morphological thickness-correction step, to recover vessel-boundary pixels, is also proposed. The significant contribution of this work is, segmentation of fine vessels while preserving the thickness of major vessels. Moreover, the algorithm is robust, as it performs consistently well, on four public databases, DRIVE, STARE, CHASE_DB-1 and HRF. Performance of the proposed algorithm is evaluated in terms of eight measures : accuracy, sensitivity, specificity, precision, F-1 score, G-mean, MCC and AUC, where it has outperformed many other existing methods. Zero data dependency gives the suggested algorithm, an edge over other state-of-the-art supervised methods.

Stress and mood of adults with moyamoya disease: A cross-sectional study.

Moyamoya disease in adults is a chronic, progressive disorder characterized by fine collateral vessel networks in the brain. The disorder can lead to negative mood and stress, which, left unresolved, may increase adverse health outcomes. We conducted a cross-sectional survey to examine stress and mood of adults with moyamoya disease. Participants were recruited at a university hospital in Seoul, Korea. Data were collected through questionnaires and review of participants' electronic medical records. A total of 109 adults participated. Significant correlations were found between perceived stress, anxiety, and depression. Adults with moyamoya disease experience anxiety, depression, and stress related to the risk of cerebral hemorrhage or ischemia, similar to those with other cerebrovascular disease. If negative mood and stress were uncontrolled, those can cuase adverse health outcomes. Health professionals caring for people with moyamoya disease should carefully observe their stress and mood and develop interventions tailored to stages of disease to help them manage. The study results provide baseline information for understanding the level of, and the factors associated with, stress and mood.

Visibility of bronchial arteries using virtual and advanced virtual monoenergetic imaging.

The utility of virtual monoenergetic imaging (VMI) for fine arteries has not been well clarified. To assess bronchial artery visualization using VMI and noise-optimized advanced VMI (VMI+). Eighty-seven patients with esophageal cancer underwent computed tomography (CT) using a third-generation dual-source system before surgery. Tube voltages were set to 90 kVp and 150 kVp, respectively. Images were reconstructed using VMI and VMI+ with energy levels of 40-120 keV (in 10-keV increments); composite images equivalent to CT images at 105 kVp were also generated. The CT attenuation value and contrast-to-noise ratio (CNR) of bronchial arteries using VMI and VMI+ were compared with those obtained using composite imaging. Two radiologists subjectively analyzed bronchial artery visualization with reference to the composite image. CT attenuation values for bronchial arteries using VMI at 40-60 keV and VMI+ at 40 keV and 50 keV were significantly higher than those obtained using composite imaging (P < 0.05). CNR using VMI at 40-60 keV was significantly higher than that obtained using composite imaging (P < 0.05), whereas no differences were noted for values obtained using composite imaging between VMI+ at 40 keV and 50 keV. In the subjective analysis, VMI at 40 keV and 50 keV yielded significantly better visibility of bronchial arteries than VMI+ (P < 0.05). VMI and VMI+ at low voltages (40-50 keV) may be useful for bronchial artery visualization. VMI+ may be less effective for fine vessels as bronchial artery visualization.

Morphological and Vascular Study Of The Posterior Lumbar Epidural Fat

Posterior lumbar epidural fat has been described by several authors in various fields: Anesthetic, Radiology and Neurochemistry. In this study, we tried to describe the position of this fat in the lumbar canal (L1-L5), its vascularization and drainage system. 8 Ivorian cadavers are used for the practice of dissection in the laboratory. The anterior abdominal region is chosen for the approach of the lumbar epidural region. The study investigated the situation, morphology and microcirculatory structure of fat at the lumbar level. The fatty clusters were embedded in fine vessels and were better vascularized and drained by veins of large caliber. In the vertebral canal, the fat was struck in the intervertebral foramina and was simply spread on the anterior surface of the ligamentum flavum. The fat as triangular shape with a vertebral base and a foamy summit it wanders in the cerebrospinal fluid. The lumbar epidural fat is better vascularized, and its venous drainage is made by large veins facing the intervertebral foramina embedded in areolar tissue traversed by nerve roots.&#x0D; Key Words: vertebral canal, fat, structure, vascularization.

Superficial Retinal Vascular Abnormalities in Schizophrenia as Shown by Swept Source OCT-Angiography: A Preliminary Study

Altered microvasculature is central to the pathophysiology of many CNS disorders, but it has received less attention in schizophrenia. Since retinal and cerebral microvessels are homologous in structure/function, the retina can be used as a window into the brain. Studies using fundus imaging in schizophrenia have identified decreased arteriole diameter and tortuosity, as well as increased venule diameter and tortuosity. Herein, we explore the ability of optical coherence tomography angiography (OCTA) to identify fine retinal vessel alterations in schizophrenia.

Rumansil I (Murça-do-Douro): um complexo artesanal antigo no Vale do Douro

A zona em torno da vila de Freixo de Numão (Vila Nova de Foz Côa) é sobejamente conhecida pela historiografia clássica devido à presença de uma série de estabelecimentos rurais no seu entorno. Entre os vários sítios romanos, destaca-se Rumansil I pela variedade de atividades aí realizadas: metalurgia de ferro e chumbo, produção cerâmica, tanto de dolia como de peças finas e comuns, e produção de vinho. Os dados disponíveis não permitem a datação do início da construção deste sítio, mas fornecem indicações de que o seu abandono terá ocorrido a partir da segunda metade do século III da nossa Era, com uma ocupação limitada durante o século IV. Rumansil I situa-se num território dominado pelo granito, a poucos quilómetros a Sul do Rio Douro. O estudo deste sítio foi fundamental para compreender a rede de estabelecimentos rurais romanos em torno de Freixo de Numão, local que, aliás, durante muito tempo, se pensava ter sido a capital de um território indígena e que terá jogado um papel importante na organização do espaço rural desta zona do Douro durante a Antiguidade.

Superb microvascular imaging (SMI) in the evaluation of musculoskeletal disorders: a systematic review

To systematically review the current literature concerning the role of superb microvascular imaging (SMI), a novel Doppler technique that enables detection of fine vessels and slow blood flow, in the evaluation of musculoskeletal disorders. An online search of the literature was conducted for the period 2013 to April 2019 and included original articles written in English language. A data analysis was performed at the end of the literature search. Eight original articles with prospective design and one with retrospective design were included in this review: 4 studies focused on rheumatoid arthritis, 2 on rheumatoid and other arthritides, 1 on lateral epicondylosis and 2 on carpal tunnel syndrome. Sample size ranged from 26 to 83 patients. Despite some methodological differences, all studies compared the performance of SMI with that of a conventional Doppler technique such as power and color Doppler and found an improvement in vascularity detection with SMI. The main variations were in sample size, evaluated parameters and vascularity interpretation methods. Inter-observer agreement for SMI ranged from moderate to excellent. SMI is a promising tool for the diagnosis and treatment planning of different musculoskeletal disorders. Future investigations should include larger samples of patients with long-term follow-up.

Ancestral Caddo Fine Ware Vessels from Cahokian Sites in the Mid-Continent, ca. A.D. 1050-1300

Ancestral Caddo ceramic vessels and ceramic vessel sherds have been identified from Cahokia and other sites in the U.S. Midwest in contexts dating from ca. A.D. 1050-1300. Archaeological findings from recent work in the East St. Louis Precinct by the Illinois State Archaeological Survey provides a wealth of data on the Mississippian ceramics found there as well as ceramic wares of likely ancestral Caddo manufacture. These Caddo wares comprise less than 0.3 percent of the more than 15,600 vessel batches in the East St. Louis Precinct assemblage, and almost all of them are on local pastes. It is probable, therefore, that these potters that had emigrated to Cahokia and were living there.

Tensor-cut: A tensor-based graph-cut blood vessel segmentation method and its application to renal artery segmentation.

Blood vessel segmentation plays a fundamental role in many computer-aided diagnosis (CAD) systems, such as coronary artery stenosis quantification, cerebral aneurysm quantification, and retinal vascular tree analysis. Fine blood vessel segmentation can help build a more accurate computer-aided diagnosis system and help physicians gain a better understanding of vascular structures. The purpose of this article is to develop a blood vessel segmentation method that can improve segmentation accuracy in tiny blood vessels. In this work, we propose a tensor-based graph-cut method for blood vessel segmentation. With our method, each voxel can be modeled by a second-order tensor, allowing the capture of the intensity information and the geometric information for building a more accurate model for blood vessel segmentation. We compared our proposed method's accuracy to several state-of-the-art blood vessel segmentation algorithms and performed experiments on both simulated and clinical CT datasets. Both experiments showed that our method achieved better state-of-the-art results than the competing techniques. The mean centerline overlap ratio of our proposed method is 84% on clinical CT data. Our proposed blood vessel segmentation method outperformed other state-of-the-art methods by 10% on clinical CT data. Tiny blood vessels in clinical CT data with a 1-mm radius can be extracted using the proposed technique. The experiments on a clinical dataset showed that the proposed method significantly improved the segmentation accuracy in tiny blood vessels.

Appearance of pediatric choroidal neovascular membranes on optical coherence tomography angiography.

Compared with fluorescein angiography (FA), the gold standard for diagnosing choroidal neovascularization (CNV) activity, optical coherence tomography angiography (OCTA) is non-invasive without risks associated with fluorescein dye use, and may be especially advantageous in the diagnosis and monitoring of children with CNV. Eight eyes from eight patients aged 12 months to 18 years were imaged with the investigational Spectralis OCTA (version 6.9, Heidelberg Engineering, Heidelberg, Germany) and the RTVue XR Avanti (Optovue Inc., Fremont, CA, USA). Two patients were imaged during examination under anesthesia while six patients were imaged in the clinic. Demographic information, ocular characteristics, treatment history, and imaging studies (color photos, fluorescein angiography, OCT) were collected and reviewed. Three eyes had active CNV while five had quiescent CNV at the time of imaging. CNV was idiopathic or secondary to trauma, retinal vascular dysgenesis versus retinopathy of prematurity, pigmentary retinopathy, Best vitelliform macular dystrophy, panuveitis, morning glory disc anomaly, and optic disc drusen. OCTA of two active CNV demonstrated presence of a main trunk with multiple fine capillaries, vessel loops, and anastomoses. OCTA was repeated after treatment for two CNV and demonstrated a decrease in size with loss of fine capillaries, vessel loops, and anastomoses. For the third active CNV, OCTA verified flow in the CNV complex despite the uncertainty of FA hyperfluorescence in the setting of grossly abnormal retinal vasculature. The five quiescent CNV all lacked fine capillaries, vessel loops, and anastomoses on OCTA. OCTA demonstrates morphological differences between active and quiescent pediatric CNV.

Ultrafine intravascular photoacoustic endoscope with a 0.7 mm diameter probe.

Intravascular photoacoustic (IVPA) imaging, benefiting from high optical contrast, large imaging depth and absorption specificity, is of great potential for lipid-rich plaque detection. However, the diameters of reported IVPA endoscopes are too big to intervene into the coronary artery branches. Here, by designing an ultracompact house embedded with a side-fire fiber and a miniature single-element ultrasound transducer, we developed an ultrafine IVPA endoscope with a diameter of 0.7mm aiming at coronary artery branches atherosclerotic plaque detection. The reliability and feasibility of the ultrafine IVPA endoscope was demonstrated by imaging a stent with a 1.6mm inner diameter. Furthermore, the photoacoustic imaging and ultrasound imaging of a mouse thoracic aorta with an inner diameter of 1.15mm was conducted to verify the clinical potentiality of the endoscope, and the PA images have good consistency with histological staining results. To the best of our knowledge, this is the first time we have achieved the IVPA imaging in fine vessel by the 0.7mm diameter ultrafine photoacoustic endoscope, which paved a way for the translation of the IVPA endoscope to clinical application.

Ultrafast Radial Modulation Imaging.

Radial modulation imaging improves the detection of microbubbles at high frequency using a dual ultrasonic excitation. However, the synchronization between the imaging pulses is nontrivial because microbubbles need to be interrogated in the compression and the rarefaction phase, and the time-delay difference from dispersion has to be corrected. To address these issues, we propose the use of ultrafast radial modulation imaging (uRMI). In this technique, a beat frequency between the modulation pulse (around 1 MHz) and the ultrafast pulse-repetition frequency was exploited to separate microbubbles from tissue phantom in vitro. This led to a modulated images' set in the spectral domain of the slow time that may then be demodulated through a digital lock-in amplifier to retrieve the contrast image. Ultrafast RMI, applied on a flow phantom with microbubbles, provided a contrast-to-tissue ratio from 7.2 to 14.8 dB at 15 MHz. For flow speed lower than 0.05 mL/min, uRMI (16 dB) provided a better contrast-to-tissue ratio than other techniques: singular value decomposition spatiotemporal filter (11 dB), amplitude modulation (9 dB), or microbubbles disruption (6 dB). This technique may then be suitable to improve the detection of targeted microbubbles, in ultrasound molecular imaging applications, and the detection of extremely slow microbubbles moving in the finest vessels in ultrasound localization microscopy.

The dynamics of Early Celtic consumption practices: A case study of the pottery from the Heuneburg.

The Early Celtic site of the Heuneburg (Baden-Wuerttemberg, Germany) has long been understood as a hallmark of early urbanization in Central Europe. The rich collection of Mediterranean imports recovered from the settlement, the elite burials in its surroundings and the Mediterranean-inspired mudbrick fortification wall further point to the importance of intercultural connections with the Mediterranean as a crucial factor in the transformation of Early Iron Age societies. We describe a new facet of this process by studying the transformation of consumption practices, especially drinking habits, brought about by intercultural encounters from the late 7th to the 5th century BC through the analysis of organic remains in 133 ceramic vessels found at the Heuneburg using Organic Residue Analysis (ORA). During the Ha D1 phase, fermented beverages, including Mediterranean grape wine, were identified in and appear to have been consumed from local handmade ceramics. The latter were recovered from different status-related contexts within the Heuneburg, suggesting an early and well-established trade/exchange system of this Mediterranean product. This contrasts with the results obtained for the drinking and serving vessels from the Ha D3 phase that were studied. The consumption of fermented beverages (wine and especially bacteriofermented products) appears to have been concentrated on the plateau. The ORA analyses presented here seem to indicate that during this time, grape wine was consumed primarily from imported vessels, and more rarely from local prestigious fine wheel-made vessels. In addition to imported wine, we demonstrate the consumption of a wide variety of foodstuffs, such as animal fats (especially dairy products), millet, plant oils and waxy plants, fruit and beehive products as well as one or several other fermented beverage(s) that were probably locally produced. Through this diachronic study of vessel function from different intra-site contexts, we inform on changing and status-related practices of food processing and consumption.

Determining Restricted Fairway Additional Width due to Bank Effect for Fine Form Vessels

In order to determine fairway width accurately and to ensure an adequate level of safety, it is necessary to fulfil different safety standards and user needs. There are a number of international recommendations for fairway design, but the recommendations by Permanent International Association of Navigation Congresses (PIANC), Puerto Del Estado (ROM 3·1) and the Japanese Ministry of Land, Infrastructure, Transport and Tourism (MLIT) are some of the best known. However, in all of these recommendations, additional width due to ship-bank effect is obsolete and needs to be improved. The objective of this paper is to use a navigational simulator with a predefined ship-bank interaction model and fine form ships models to determine the ship trajectory caused by ship-bank effect. The methodology of research used in the paper consisted of using ship trajectory data to propose a deterministic model for improving fairway additional width due to ship-bank effect. Results showed that such a method is not time-consuming and can improve fairway design in terms of ship-bank effect, increasing additional width accuracy.

Osteonecrosis of the femoral head: pathophysiology and current concepts of treatment.

Osteonecrosis of the femoral head is a disabling pathology affecting a young population (average age at treatment, 33 to 38 years) and is the most important cause of total hip arthroplasty in this population. It reflects the endpoint of various disease processes that result in a decrease of the femoral head blood flow.The physiopathology reflects an alteration of the vascularization of the fine blood vessels irrigating the anterior and superior part of the femoral head. This zone of necrosis is the source of the loss of joint congruence that leads to premature wear of the hip.Several different types of medication have been developed to reverse the process of ischemia and/or restore the vascularization of the femoral head. There is no consensus yet on a particular treatment.The surgical treatments aim to preserve the joint as far as the diagnosis could be made before the appearance of a zone of necrosis and the loss of joint congruence. They consist of bone marrow decompressions, osteotomies around the hip, vascular or non-vascular grafts.Future therapies include the use of biologically active molecules as well as implants impregnated with biologically active tissue.Cite this article: EFORT Open Rev 2019;4:85-97. DOI: 10.1302/2058-5241.4.180036

Resilience in hierarchical fluid flow networks.

The structure of flow networks determines their function under normal conditions as well as their response to perturbative damage. Brain vasculature often experiences transient or permanent occlusions in the finest vessels, but it is not clear how these microclots affect the large-scale blood flow or to what extent they decrease functionality. Motivated by this, we investigate how flow is rerouted after the occlusion of a single edge in networks with a hierarchy in edge conductances. We find that in two-dimensional networks, vessels formed by highly conductive edges serve as barriers to contain the displacement of flow due to a localized perturbation. In this way, the vein provides shielding from damage to surrounding edges. We show that once the conductance of the vein surpasses an initial minimal value, further increasing the conductance can no longer extend the shielding provided by the vein. Rather, the length scale of the shielding is set by the network topology. Upon understanding the effects of a single vein, we investigate the global resilience of networks with complex hierarchical order. We find that a system of veins arranged in a grid is able to modestly increase the overall network resilience, outperforming a parallel vein pattern.