Vascular Network Structure Research Articles

Features of vascular anatomy in pancreaticoduodenal resection

In about 55–79% of patients, the vascular anatomy of the hepatic-pancreaticoduodenal area is characterized by a typical structure. In the rest of patients, the vascular and, primarily, arterial anatomy may vary due to both different variants of branches and additional arteries. Undoubtedly, this creates difficulties in surgical planning and performing pancreaticoduodenal resection. Vascular anatomic variations may contribute to increased intraoperative blood loss, postoperative complications, changes in the course and volume of surgery, and increased duration of hospital stay after surgery. Modern diagnostic methods, CT angiography in particular, facilitate the process of surgical planning and reduce the risk of unforeseen situations related to ligation or damage of arterial vessels, which are to be preserved during operations. In this work, we carry out a review of publications on the topography of arterial vessels in the area of pancreaticoduodenal resection. The issues related to anatomical variations in both trunk and pancreatic vessels are considered. Special attention is paid to the possible influence of variations in the vascular network structure on the course and volume of surgery, as well as the risk of intraoperative and postoperative complications.

Polysaccharides from Ostrea rivularis alleviate type II diabetes induced-retinopathy and VGEF165-induced angiogenesis via PI3K/AKT signaling pathway

The purpose of this study was to investigate the role of polysaccharides from Ostrea rivularis Gloud (ORPs) in the progression of diabetic retinopathy (DR) and its anti-angiogenic effect on endothelial cell. Transgenic db/db mice with DR model were used to evaluate the protective effect of ORPs on retinal damage. It was found that ORPs could down-regulated levels of random blood glucose and fasting insulin, and further ameliorate retinal structure abnormalities as well as vascular network structure. Moreover, ORPs could reduce the expression of VEGF in retinal tissue and lessen pathological angiogenesis, thus slowing the progression of DR. In vitro, the proliferation, migration and tube formation of VGEF165-induced EA.hy926 cells were inhibited with ORPs administration. Furthermore, the expression of related proteins in the PI3K/AKT pathway and angiogenesis related factors were improved after ORPs intervention. Overall, these findings suggested that ORPs could effectively control the development of DR, and inhibit VGEF165-induced EA.hy926 cells proliferation, migration and tube formation, which effects might work through blocking the activation of PI3K/AKT signaling pathway.

Abstract PR015: Interpretable computational pathology reveals that vascular networks reflect evolutionary dynamics in kidney cancer

Abstract Clear cell Renal Cell Carcinoma (ccRCC) is profoundly angiogenic, characterised by complex yet heterogenous vascular networks. Blood vessels are an important constituent part of the tumour microenvironment (TME) and, in addition to immune cells, are the target of drug therapies in advanced disease. The TME plays an important role in determining disease progression and response to therapy, acting as a selective pressure on the tumour cells thus influencing evolutionary trajectory. This selective pressure is sculpted by cross-talk between blood vessels, immune cells and the tumour cells themselves. Whilst the details of these carefully orchestrated cellular interactions is not understood their final read-out is reflected in tissue morphology, which can be assessed using an H&E-stained slide, a fundamental component of clinical diagnostic histopathological workflows. A computational pathology approach to assess vascular networks from digital H&E whole slide images (H&E WSIs) would present a powerful tool to understand disease biology. It would permit high-throughput analysis of large cohorts where routine multi-regional sampling captures disease heterogeneity. Such work would lay the foundations for developing a computational pathology biomarker to predict survival outcomes that could be easily implemented into existing clinical workflows. Intricacy of vascular network structures makes reproducible analysis challenging, which can be approached either using morphology, a qualitative evaluation of a shape, or using topography to quantify feature dimensions. Here we reconcile the two methods to develop an interpretable computational pathology solution to study the blood vessels in ccRCC. Further, we have built a deep-learning attention UNET model to segment blood vessels from H&E WSIs. By combining these tools we have developed a computational pathology pipeline able to robustly characterise vascular networks directly from H&E WSIs. We leverage 1064 tumour regions from 82 ccRCC tumours of the TRACERx Renal dataset where ex-vivo multi-regional sampling with closely linked specimens for histological and genomic analysis permits interrogation of the histo:genomic relationship contextualised within the evolutionary dynamics of each tumour. We demonstrate that vascular intratumoral heterogeneity is pervasive and we link different vascular topologies to genetic alterations associated with opposing evolutionary trajectories (PBRM1 and BAP1 mutations) and the acquisition of metastatic competence (loss of 9p). Finally, we show that progressive accumulation of genetic alterations alters vascular network structure, suggesting that vascular topology could be used to assess tumour evolution. Our pipeline is a powerful tool to study ccRCC vasculature in large cohorts with multi-regional sampling to capture intratumoral heterogeneity and ultimately could form the basis of a computational pathology biomarker to predict outcome to therapy. Citation Format: Charlotte E. Spencer, Graham Ross, Thomas Mead, Amy Strange, Anna Song, Katie Bentley, Samra Turajlic. Interpretable computational pathology reveals that vascular networks reflect evolutionary dynamics in kidney cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Translating Cancer Evolution and Data Science: The Next Frontier; 2023 Dec 3-6; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(3 Suppl_2):Abstract nr PR015.

A Deep Learning Approach for Improving Two-Photon Vascular Imaging Speeds.

A potential method for tracking neurovascular disease progression over time in preclinical models is multiphoton fluorescence microscopy (MPM), which can image cerebral vasculature with capillary-level resolution. However, obtaining high-quality, three-dimensional images with traditional point scanning MPM is time-consuming and limits sample sizes for chronic studies. Here, we present a convolutional neural network-based (PSSR Res-U-Net architecture) algorithm for fast upscaling of low-resolution or sparsely sampled images and combine it with a segmentation-less vectorization process for 3D reconstruction and statistical analysis of vascular network structure. In doing so, we also demonstrate that the use of semi-synthetic training data can replace the expensive and arduous process of acquiring low- and high-resolution training pairs without compromising vectorization outcomes, and thus open the possibility of utilizing such approaches for other MPM tasks where collecting training data is challenging. We applied our approach to images with large fields of view from a mouse model and show that our method generalizes across imaging depths, disease states and other differences in neurovasculature. Our pretrained models and lightweight architecture can be used to reduce MPM imaging time by up to fourfold without any changes in underlying hardware, thereby enabling deployability across a range of settings.

Evaluation of tissue blood supply during esophagectomy using fluorescent diagnostics and diffuse scattering spectroscopy in visible region

BackgroundThe success of the surgical treatment of a tumor or obstruction of the esophagus with subsequent anastomosis application depends on the level of blood supply to the stitched tissues. Intraoperative assessment of blood flow is widely used in medicine and can be used as a diagnostic method that affects the outcome of surgery and reduces the frequency of postoperative complications for the patient. MethodsIn this work, the assessment of blood supply during esophageal resection operations was carried out using two techniques sequentially: fluorescent diagnostics with indocyanine green and measurement of hemoglobin oxygen saturation by diffuse scattering spectroscopy in the visible wavelength range. The first method was used to assess the integrity of the vascular network structure in the area of anastomosis and blood flow through the sutured tissues, the second one – for local assessment of hemoglobin oxygen saturation in the investigated area. ResultsConducted clinical study involved the participation of nine patients with malignant neoplasms (six cases) or esophageal obstruction (three cases). The presence of postoperative complications was compared with the measurement results. Anastomosis failure was observed in only one patient. According to the results of the study, with the use of the investigated method of assessing blood supply, there is a tendency towards a decrease in the frequency of anastomosis leaks (11.1 % compared with 21.4 %). ConclusionsTherefore, fluorescent diagnostics with indocyanine green and measurement of hemoglobin oxygen saturation using diffuse scattering spectroscopy were affirmed as methods that allow increasing the safety of surgical procedures by assessing the risk of postoperative complications, including anastomosis failures.

Computational modeling and simulation for endovascular embolization of cerebral arteriovenous malformations with liquid embolic agents

Endovascular embolization of arteriovenous malformations (AVMs) in the brain usually requires injecting liquid embolic agents (LEAs) to reduce blood flow through the malformation. In clinical procedures, the feeding artery into which the LEAs are injected, and the amount of LEAs needs to be carefully planned preoperatively. Computational fluid dynamics can simulate the injecting process of LEAs in nidus and evaluate the therapeutic effects of different procedures preoperatively. Applying a porous media model avoided the difficulties of geometric modeling of AVMs, and the complex vascular network structure within the nidus was reproduced. The multi-phase flow was applied to simulate the interaction between LEAs and blood. The viscosity of LEAs is determined by the concentration of its solute ethylene-vinyl alcohol copolymer (EVOH). The diffusion process of the solvent dimethyl sulfoxide (DMSO) was calculated by solving the species transport equation. The coagulation of LEAs was simulated by constructing the relationship between the concentration of EVOH and viscosity. The numerical simulation method of LEAs for injection and coagulation was tested on two patient-specific AVMs. The calculations predicted the flow direction of the LEAs in the nidus. The morphology of the injected LEAs could be well visualized by 3D rendering. Quantitative analysis was conducted, including flow rate changes at the feeding arteries and draining veins. The embolization process of AVMs with LEAs can be simulated by computational fluid dynamics (CFD) methods to show the therapeutic effects of different embolization procedure planning, the optimal treatment plan can be determined.

Preparation of a scaffold for a vascular network channel with spatially varying diameter based on sucrose

In the past few decades, although tissue engineering has made significant progress and achieved many accomplishments, there are still some key problems that remain unsolved. One of the urgent research challenges in this field is how to prepare large-scale tissue engineering scaffolds with spatially complex structures. In this work, a sacrificial template process using sucrose as the sacrificial material and a gelatin/microbial transglutaminase mixed solution as the bio-scaffold material is proposed to fabricate a bio-scaffold with multi-level branching and spatially complex vascular network channels that mimic the structure and function of the human vascular network. To validate the feasibility of the fabrication process and the rationality of the process parameters, the morphological characteristics, connectivity of vascular network channels, shaping accuracy, and mechanical properties of the bio-scaffold were tested and analyzed. The results showed that the bio-scaffold fabricated using this process had a complete morphology and excellent connectivity. The diameter of the sucrose sacrificial template showed a linear relationship with the feeding speed, and the average diameter error rate between the sucrose sacrificial template and the vascular network channels inside the bio-scaffold was less than 8%. The mechanical properties of the bio-scaffold met the requirements for large-scale tissue defect repair. To evaluate the effect of the bio-scaffold on cell activity, human umbilical vein endothelial cells (HUVECs) were seeded into the vascular network channels of the bio-scaffold, and their attachment, growth, and proliferation on the surface of the vascular network channels were observed. To further assess the biocompatibility of the bio-scaffold, the bio-scaffold was implanted subcutaneously in the dorsal tissue of rats, and the tissue regeneration status was compared and analyzed through immunohistochemical analysis. The results showed that the vascular network channels within the bio-scaffold allowed uniform cell attachment, growth, with fewer dead cells and high cell viability. Moreover, clear cell attachment and growth were observed within the vascular network channels of the bio-scaffold after implantation in rats. These results indicate that the fabricated bio-scaffold meets the basic performance requirements for the repair and regeneration of large-scale tissue defects, providing a new approach for oxygen and nutrient transport in large-scale tissues and opening up new avenues for clinical applications.

Interpreting inverse correlation time: From blood flow to vascular network

The inverse correlation time (ICT) is a key quantity in laser speckle contrast imaging (LSCI) measurements. Traditionally, ICT is regarded as a metric of blood flow, such as speed or perfusion. However, we highlight that ICT not only contains important information about blood flow, but also reflects the underlying structure of the vascular network. In the past, ICT has been found to be correlated with vessel diameter. Here, we further report that ICT exhibits a different sensitivity to blood flow depending on vessel orientation. Specifically, ICT is more sensitive to blood flow speed changes in vessels descending from or arising to the tissue surface, compared with those laying parallel to the surface. Those findings shift our understanding of ICT from purely blood flow to a combination of blood flow and vascular network structure. We also develop theories to facilitate the study of vascular network’s impact on ICT.

Decellularization of renal fibrosis by cyclic hydrostatic pressure to restore renal function

Natural extracellular matrices (ECM) are currently being studied as an alternative source for organ transplantation or as new solutions to treat end-stage renal disease. As the gap between donors and patients in need of an organ transplant continues to widen, research in regenerative medicine seeks to provide different strategies for treatment Tissue and organ failure is currently one of the biggest health issues our society faces [1]. Arising from disease or trauma, complete treatment typically requires the repair or replace the affected organ However, the unavailability of adequate organs for transplantation to meet the existing demand has resulted in major organ shortage crisis. As a result, there has been a major increase in the number of patients [2]. The stem cell therapy fails because of the toxic environment in the organ, the implanted cells unable to regenerate. Afterwards researchers are trying to prepare the lab made artificial organ in the laboratory with the help of artificial scaffold and the tissue specific stem cells. Then tried for the transplantation of animal organs. To overcome this organ shortage challenge is the use of organ-derived scaffolds obtained via decellularization techniques by removing all viable cells from native tissues and retaining 3D structure of natural extracellular matrix (ECM) and vascular network for regeneration. This is the most adequate method where scaffold thoroughly decellularizes, free of endotoxin or bacterial contamination. An appropriate macro and microstructure to support physiological function, intact vascular tree, specific location cues.

Long-term risk of cardiovascular and cerebrovascular disease in women with a personal history of placental abruption

Maternal and perinatal health is one of today’s global health priorities. Cardiovascular disease and stroke are the leading causes of maternal mortality. Placental abruption remains a critical concern for maternal morbidity because it has been associated with long-term vascular disease. However, there is neither much literature available in Spanish nor recent evidence elucidating some questions on this topic. Thus, this review aims to synthesize recent evidence on the long-term risk of cardiovascular and cerebrovascular disease in women with a personal history of placental abruption. It was found that, through complex pathophysiological mechanisms involving the structure and functionality of the placental vascular network with subsequent extension of vascular injury and production of proinflammatory and procoagulant factors which remain after delivery, major cardiovascular events are precipitated in the medium and long term. High-quality evidence has shown that the risk of maternal complications in women with placental abruption accounts for 2.14, rising even higher for those with severe placental abruption. In the medium and long term, the mortality risk caused by coronary heart diseases is 2.64 and by cerebrovascular disorders is 1.70, with equal risk for both ischemic and hemorrhagic strokes. It can therefore be concluded that cardiovascular and cerebrovascular risk is imminent in women with a history of placental abruption due to a number of vascular pathophysiological mechanisms. However, this risk is considerably increased when associated with traditional and non-traditional modifiable factors.

A hierarchical vascularized engineered bone inspired by intramembranous ossification for mandibular regeneration

Mandibular defects caused by injuries, tumors, and infections are common and can severely affect mandibular function and the patient’s appearance. However, mandible reconstruction with a mandibular bionic structure remains challenging. Inspired by the process of intramembranous ossification in mandibular development, a hierarchical vascularized engineered bone consisting of angiogenesis and osteogenesis modules has been produced. Moreover, the hierarchical vascular network and bone structure generated by these hierarchical vascularized engineered bone modules match the particular anatomical structure of the mandible. The ultra-tough polyion complex has been used as the basic scaffold for hierarchical vascularized engineered bone for ensuring better reconstruction of mandible function. According to the results of in vivo experiments, the bone regenerated using hierarchical vascularized engineered bone is similar to the natural mandibular bone in terms of morphology and genomics. The sonic hedgehog signaling pathway is specifically activated in hierarchical vascularized engineered bone, indicating that the new bone in hierarchical vascularized engineered bone underwent a process of intramembranous ossification identical to that of mandible development. Thus, hierarchical vascularized engineered bone has a high potential for clinical application in mandibular defect reconstruction. Moreover, the concept based on developmental processes and bionic structures provides an effective strategy for tissue regeneration.

Histology and Vascular Architecture Study of Keloid Tissue to Outline the Possible Terminology of Keloid Skin Flaps.

Using the keloid "epidermis" to cover a wound is widely used during treatment for keloids. Many flap terminologies have been used in literature. However, the definition of the flap is not well established. Here, we refined the definition of the flap and associated terminology and explored the survival mechanism of the 'flap' through histological analysis and blood supply studying. Histology and vascular study of keloid was carried out with keloid and its surrounding normal skin tissue which were collected from keloid patients following keloid resection operations. The histological structures and thicknesses of epidermal and subepidermal of the keloids were analyzed and measured using hematoxylin & eosin (H&E) staining. Vascular density and blood perfusion in the subepidermal layer of keloids (KDS) were analyzed using CD31 immunohistochemical staining and a laser speckle contrast imaging system (LSCI), respectively. The vascular network in KDS was visualized by CD31 immunofluorescence staining and three-dimensional reconstruction. 29 pieces of keloid and its surrounding normal skin tissue sample from ten patients were collected. Keloid samples were about 2 cm wide and 5 cm long. The normal skin samples were about 2 to 3 mm in width. The thickness of epidermal layer of keloids was (136.4 ± 35.3) μm, and the thickness of epidermal layer of surrounding normal skin was (78.8 ± 13.9) μm. There was statistical thickness difference between the two layers, t(20) = 7.469, P < 0.001. The total thickness of keloid epidermal and subepidermal layers was 391.4 ± 2.3 μm. The vascular density (13.9 ± 3.4/field) and blood flow perfusion (132.7 ± 31.3) PU in KDS were greater than that of surrounding normal skin (7.8 ± 2.3/field, 73.9 ± 17.9 PU), P < 0.001. Horizontally distributed vessels with several vertical branches were observed in 3D vascular network reconstruction. The epidermal layer of keloid is thicker than that of surrounding normal skin. There is a vascular network structure under it. The vessels mainly locate at a depth of about 150 to 400 μm from the surface of keloid epidermis, randomly distribute and run parallel to the epidermis. Based on these characteristics which may ensure an adequate blood supply, we propose the concept of a "keloid subepidermal vascular network flap." This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

A multiscale model of complex endothelial cell dynamics in early angiogenesis.

We introduce a hybrid two-dimensional multiscale model of angiogenesis, the process by which endothelial cells (ECs) migrate from a pre-existing vascular bed in response to local environmental cues and cell-cell interactions, to create a new vascular network. Recent experimental studies have highlighted a central role of cell rearrangements in the formation of angiogenic networks. Our model accounts for this phenomenon via the heterogeneous response of ECs to their microenvironment. These cell rearrangements, in turn, dynamically remodel the local environment. The model reproduces characteristic features of angiogenic sprouting that include branching, chemotactic sensitivity, the brush border effect, and cell mixing. These properties, rather than being hardwired into the model, emerge naturally from the gene expression patterns of individual cells. After calibrating and validating our model against experimental data, we use it to predict how the structure of the vascular network changes as the baseline gene expression levels of the VEGF-Delta-Notch pathway, and the composition of the extracellular environment, vary. In order to investigate the impact of cell rearrangements on the vascular network structure, we introduce the mixing measure, a scalar metric that quantifies cell mixing as the vascular network grows. We calculate the mixing measure for the simulated vascular networks generated by ECs of different lineages (wild type cells and mutant cells with impaired expression of a specific receptor). Our results show that the time evolution of the mixing measure is directly correlated to the generic features of the vascular branching pattern, thus, supporting the hypothesis that cell rearrangements play an essential role in sprouting angiogenesis. Furthermore, we predict that lower cell rearrangement leads to an imbalance between branching and sprout elongation. Since the computation of this statistic requires only individual cell trajectories, it can be computed for networks generated in biological experiments, making it a potential biomarker for pathological angiogenesis.

A Hybrid Unsupervised Approach for Retinal Vessel Segmentation.

Retinal vessel segmentation (RVS) is a significant source of useful information for monitoring, identification, initial medication, and surgical development of ophthalmic disorders. Most common disorders, i.e., stroke, diabetic retinopathy (DR), and cardiac diseases, often change the normal structure of the retinal vascular network. A lot of research has been committed to building an automatic RVS system. But, it is still an open issue. In this article, a framework is recommended for RVS with fast execution and competing outcomes. An initial binary image is obtained by the application of the MISODATA on the preprocessed image. For vessel structure enhancement, B-COSFIRE filters are utilized along with thresholding to obtain another binary image. These two binary images are combined by logical AND-type operation. Then, it is fused with the enhanced image of B-COSFIRE filters followed by thresholding to obtain the vessel location map (VLM). The methodology is verified on four different datasets: DRIVE, STARE, HRF, and CHASE_DB1, which are publicly accessible for benchmarking and validation. The obtained results are compared with the existing competing methods.

Investigation of the human pineal gland 3D organization by X-ray phase contrast tomography

Pineal gland (PG) is a part of the human brain epithalamus that plays an important role in sleep, circadian rhythm, immunity, and reproduction. The calcium deposits and lesions in PG interfere with normal function of the organ and can be associated with different health disorders including serious neurological diseases. At the moment, the detailed mechanisms of PG calcifications and PG lesions formation as well as their involvement in pathological processes are not fully understood. The deep and comprehensive study of the structure of the uncut human PG with histological details, poses a stiff challenge to most imaging techniques, due to low spatial resolution, low visibility or to exceedingly aggressive sample preparation. Here, we investigate the whole uncut and unstained human post-mortem PGs by X-ray phase contrast tomography (XPCT). XPCT is an advanced 3D imaging technique, that permits to study of both soft and calcified tissue of a sample at different scales: from the whole organ to cell structure. In our research we simultaneously resolved 3D structure of parenchyma, vascular network and calcifications. Moreover, we distinguished structural details of intact and degenerated PG tissue. We discriminated calcifications with different structure, pinealocytes nuclei and the glial cells processes. All results were validated by histology. Our research clear demonstrated that XPCT is a potential tool for the high resolution 3D imaging of PG morphological features. This technique opens a new perspective to investigate PG dysfunction and understand the mechanisms of onset and progression of diseases involving the pineal gland.

Placental vascular tree characterization based on ex-vivo MRI with a potential application for placental insufficiency assessment

IntroductionUnderstanding regarding the whole placental vascular network structure is limited. Our aim was to quantitatively characterize the human placental vascular tree ex-vivo using high-resolution MRI. Methods34 normal placentas were rinsed and injected with a solution of gelatin and contrast agent through the umbilical vessels. A sample of six placentas taken from pregnancies with intrauterine-growth-restriction (IUGR) was used to demonstrate the potential application to cases with placental insufficiency. Structural ex-vivo MR scans of the placenta were performed using high resolution T1 weighted images. A semi-automatic method was developed to segment and characterize the placental vascular architecture: placental volume and cord insertion location, number of bifurcations, generations and vessels diameters. ResultsDifferent vascular patterns were found in placentas with central versus marginal cord-insertion. Based on the placental volume and number of bifurcations we were able to predict birth weight. Furthermore, preliminary results on IUGR sample demonstrated the potential of this method to differentiate between small newborns with suspected IUGR from small normal newborns who reached their full growth potential. Results obtained using the automatic method were validated against manual values demonstrating no significant differences or bias. Histopathology supported the imaging findings. DiscussionThis is the first study to quantitatively characterize the human placental vascular architecture using high resolution ex-vivo MRI. Different patterns of vascular architecture may be related to different functioning of the placenta and affect fetal development. This method is simple, relatively fast, provides detailed information of the placental vascular architecture, and may have important clinical applications.

A four-compartment multiscale model of fluid and drug distribution in vascular tumours.

The subtle relationship between vascular network structure and mass transport is vital to predict and improve the efficacy of anticancer treatments. Here, mathematical homogenisation is used to derive a new multiscale continuum model of blood and chemotherapy transport in the vasculature and interstitium of a vascular tumour. This framework enables information at a range of vascular hierarchies to be fed into an effective description on the length scale of the tumour. The model behaviour is explored through a demonstrative case study of a simplified representation of a dorsal skinfold chamber, to examine the role of vascular network architecture in influencing fluid and drug perfusion on the length scale of the chamber. A single parameter, P, is identified that relates tumour‐scale fluid perfusion to the permeability and density of the capillary bed. By fixing the topological and physiological properties of the arteriole and venule networks, an optimal value for P is identified, which maximises tumour fluid transport and is thus hypothesised to benefit chemotherapy delivery. We calculate the values for P for eight explicit network structures; in each case, vascular intervention by either decreasing the permeability or increasing the density of the capillary network would increase fluid perfusion through the cancerous tissue. Chemotherapeutic strategies are compared and indicate that single injection is consistently more successful compared with constant perfusion, and the model predicts optimal timing of a second dose. These results highlight the potential of computational modelling to elucidate the link between vascular architecture and fluid, drug distribution in tumours.

A novel method to model hepatic vascular network using vessel segmentation, thinning, and completion.

The accurate modeling of the liver vessel network structure is an important prerequisite for developing a preoperative plan for the liver. Considering that extracting liver blood vessels from patient's abdominal computed tomography(CT) images requires several manual operations, this study proposed an automatic segmentation method of liver vessels based on graph cut, thinning, and vascular combination, which can obtain a complete liver vascular network. First, the CT image was preprocessed by grayscale mapping based on sigmoid function, vessel enhancement based on Hessian filter, and denoising based on anisotropic filter to enhance the grayscale contrast between the vascular and non-vascular parts of the liver. Then, the liver vessels were initially segmented based on the improved three-dimensional graph cut algorithm. Based on the obtained liver vascular structure, the vessel centerline of the liver was then extracted by the proposed thinning algorithm that continuously traversed the foreground voxel points and iteratively deleted the simple points. Finally, the combination of vascular centerline optimization was used to predict and link the vascular centerline fractured portion. The under-segmented liver vessels were complemented based on the complete vascular centerline tree. To verify the proposed hepatic vascular segmentation and complementation algorithm, the open 3D Image Reconstruction for Comparison of Algorithm Database (3Dircadb) was applied to test and quantify the results. The results showed that the proposed algorithm can accurately and effectively segment the vascular network structure from abdominal CT images, and the proposed vascular complementation method can restore the true information of under-segmented liver vessels. Graphical abstract A novel hepatic vessel segmentation method from abdominal CT images was proposed, including graph cut algorithm, centerline extraction, and broken vessel completion. First, the graph cut algorithm was used to obtain the initial segmentation result. Then, the centerline of the initial segmentation result was extracted. Finally, the initial segmentation result was optimized through centerline analysis.

A framework for hierarchical division of retinal vascular networks

Human retinal vascular network plays an important role in ophthalmology diagnosis. For example, in the diagnosis of ophthalmology, the severity of the disease has a direct correlation with the lesion location, in the sense that the closer the lesion area is to the optic disk, the higher will be the severity of the disease. If a framework is able to provide the hierarchical structure of the retinal vascular network, then the severity of disease can be quantified by leveraging the hierarchical characteristics of vessels in the vicinity of the lesion location. Thus, in this paper, an executable framework is recommended for the hierarchical division of the retinal vascular networks. Specifically, a supervised method based on deep neural network is used for retinal blood vessel segmentation. A graph-based method is also applied to generate vascular trees from the segmented retinal vessels. As part of our proposed approach, we present two algorithms: the potential landmark detection algorithm (PLDA) is used to identify the bifurcations and crossings; and the adaptive hierarchical classification algorithm (AHCA) is used in the hierarchical characteristics classification of vascular bifurcations. By classifying the hierarchical characteristics of vascular bifurcation, the hierarchical characteristics of the vessel segments containing these bifurcations are identified. Thus, the hierarchical division of retinal vascular network is realized. When applied to two publicly available datasets, DRIVE and STARE, the proposed framework achieves an accurate rate of 98.99% and sensitivity rate of 92.17%.

Pseudo-Biological Highly Performance Transparent Electrodes Based on Capillary Force-Welded Hybrid AgNW Network

Graphene/silver nanowire composite films have great potential as transparent conductive electrodes in the field of optoelectronic devices. So far, antioxidant and reducing the junction resistance are two major parameters in the silver nanowire electrode studies. In this paper, a pseudo-biological inspired structure for transparent electrodes was proposed by combining hybrid diameters silver nanowire network with the chemical vapor deposition-grown (CVD-grown) graphene as a passivation layer. Compared with the traditional structure, the silver nanowire network with this novel structure of human vascular tissue network greatly reduced the sheet resistance. An environmentally friendly liquid, deionized water, was selected for the generation of capillary forces at the liquid bridge, thereby improving the wire junction problem. After welding with the capillary force, the increase in the value of the figure of merit (FoM = σ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DC</sub> /σ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OP</sub> ) acted a pivotal part in improving conductivity with excellent optical performance. In addition, graphene was chosen as an encapsulation layer to protecting silver nanowires from oxidation while improving electrical properties. Compared with the silver nanowire films with a diameter of 20 nm, the σ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DC</sub> /σ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OP</sub> of the graphene/silver nanowire composite film increased by 69.6 % with a sheet resistance of 26.4 Ω/sq. More importantly, graphene is supposed to protect silver nanowires from oxidation and moisture, which makes the composite films promising as electrodes for underwater optoelectronic devices or a possible development in high humidity environments.