Configuration Of Blood Vessels Research Articles

The Use of Fusion Images as a Diagnostic and Neurosurgical Planning Tool in Microvascular Decompression.

Preoperative assessment of surgery using high-quality images can help surgeons to achieve best result of treatment. With the advances in computer technology, interactive multimodality fusion images have been developed. The use of fusion images as a preoperative planning tool is described with its examples in illustrative cases of trigeminal neuralgia and hemifacial spasm microvascular decompression (MVD). Interactive computer graphics such as multimodality fusion method is a useful tool to preoperatively predict the need of bone exposure and configuration of blood vessels with its correlation to cranial nerves in MVD.

Simulation study of the cooling effect of blood vessels and blood coagulation in hepatic radio-frequency ablation

Purpose Computer simulations of hepatic radio-frequency ablation (RFA) were performed to: (i) determine the dependence of the vessel wall heat transfer coefficient on geometrical parameters; (ii) study the conditions required for the occurrence of the directional effect of blood; and (iii) classify blood vessels according to their effect on the thermal lesion while considering blood coagulation. The information thus obtained supports the development of a multi-scale bio-heat model tailored for more accurate prediction of hepatic RFA outcomes in the vicinity of blood vessels. Materials and methods The simulation geometry consisted of healthy tissue, tumor tissue, a mono-polar RF-needle, and a single cylindrical blood vessel. The geometrical parameters of interest were the RF-needle active length and those describing blood vessel configuration. A simple, novel method to incorporate the effects of blood coagulation into the simulation was developed and tested. Results A closed form expression giving the dependence of the vessel wall heat transfer coefficient on geometrical parameters was obtained. Directional effects on the thermal lesion were found to occur for blood vessel radii between 0.4 mm and 0.5 mm. Below 0.4 mm blood coagulation blocked the flow. Conclusions The closed form expression for the heat transfer coefficient can be used in models of RFA to speed up computation. The conditions on vessel radii required for the occurrence of directional effects on the thermal lesion were determined. These conditions allow the classification of blood vessels. Different approximations to the thermal equation can thus be used for these vessel classes.

Pilot Study: The role of chronic stress on brain microvessel density in male and female mice

The cerebrovasculature, an intricate configuration of blood vessels, is responsible for the exchange of blood to and from the brain. Reduction of cerebrovascular vessels can reduce or prevent the flow of nutrients & oxygen that is necessary for proper brain function and increase risk of cerebrovascular diseases. Chronic stress is also a risk factor to various cerebrovascular diseases.In this pilot study, brain microvessel density in both female and male chronically stressed mice were analyzed. Beginning at the age of 18 weeks, mice were subjected to the unpredictable chronic mild stress (UCMS) paradigm for 5 days a week/seven hours a day for 8 weeks. Upon euthanization brain samples were flash frozen and sectioned at 8um using a cryostat. Immunofluorescence was utilized to observe endothelial cells via a CD31 antibody. Images were taken using a Nikon Eclipse 800 at a 40X objective and analyzed and quantified for density using ImageJ.Preliminary data (n=3/group) suggest that the male mice have a 26% higher microvessel density compared to females (p<0.05). When stressed, males exhibit a 17% lower microvessel density whereas stressed females did not display a loss in microvessel density (p<0.05).Here we showed that the brain of male and female mice can be physiologically diverse in microvessel density and that males and females display a different response when exposed to chronic stress.Support or Funding InformationNIH Cobra Grant 5P20GM109098; NIH INBRE P20GM103434

Qualitative and Quantitative Comparison of Hemodynamics Between MRI Measurement and CFD Simulation on Patient-specific Cerebral Aneurysm – A Review

The significant progress in computer innovation technique, computational fluid dynamics (CFD) has been applied for real applications on patient-specific hemodynamics and extensively used to study cerebral aneurysm rupture. In addition, the computational study with representative blood vessel configuration has become a great tool in providing comprehensive information on geometry, the flow field of blood and wall shear stress (WSS). Generally, the numerical simulations have an expected problem on the specification of the exact boundary conditions which leads to unphysical numerical solutions. Therefore, this paper tends to find out whether CFD simulation manages to obtain precise and better predictions of hemodynamics patterns at present time especially for phase-contrast magnetic resonance imaging (PC-MRI) in terms of the velocity flow field and WSS distribution. Several research articles are included and their qualitative and quantitative results on hemodynamics have been compared. Both MRI measurement and CFD simulation have reasonably good agreement on velocity flow fields and a detailed spiral recirculating flow pattern can be observed in CFD simulation as compared to MRI measurement instead. However, CFD simulation has overestimated the WSS, especially at the maximum WSS location. The CFD simulation is capable to achieve good agreement on velocity flow fields with MRI measurement, yet the result for WSS distribution has to be further improved and justified with consistent assumptions and techniques.

The Humboldt Penguin (Spheniscus humboldti) Rete Tibiotarsale – A supreme biological heat exchanger

Humans are unable to survive low temperature environments without custom designed clothing and support systems. In contrast, certain penguin species inhabit extremely cold climates without losing substantial energy to self-heating (emperor penguins ambient temperature plummets to as low as −45°C). Penguins accomplish this task by relying on distinct anatomical, physiological and behavioral adaptations. One such adaptation is a blood vessel heat exchanger called the ‘Rete Tibiotarsale’ – an intermingled network of arteries and veins found in penguins’ legs. The Rete existence results in blood occupying the foot expressing a lower average temperature and thus the penguin loosing less heat to the ground. This study examines the Rete significance for the species thermal endurance. The penguin anatomy (leg and main blood vessels) is reconstructed using data chiefly based on the Humboldt species. The resulting model is thermally analyzed using finite element (COMSOL) with the species environment used as boundary conditions. A human-like blood vessel configuration, scaled to the penguin's dimensions, is used as a control for the study. Results indicate that the Rete existence facilitates upkeep of 25−65% of the species total metabolic energy production as compared with the human-like configuration; thus making the Rete probably crucial for penguin thermal endurance. Here, we quantitatively link for the first time the function and structure of this remarkable physiological phenotype.

Analysis of the symmetric configuration of the circle of Willis in a series of autopsied corpses.

The forming of the blood vessels network configuration at the base of the brain and interconnecting of blood vessels during the embryogenesis is directly related to the phylogenetic development of the brain and brain structures. A blood vessel configuration at the brain base, in the form of a ring or a hexagon, stands in direct relation to the perfusion needs of certain parts of the brain during its primary differentiation. The aim of this paper was to determine the incidence of certain blood vessel configurations at the base of the brain and understanding their symmetry or asymmetry. Analysis of the blood vessels at the base of the brain was performed on the autopsied subjects. The object of observation was the anterior segment of the circle of Willis consisting of C1- a. carotis interna (ICA), above a. communicaus posterior (PcoA), the segment A1 a. cerebri anterior (ACA) from a. carotis interna bifurcation to the a. communicans anterior (AcoA) and a communicans anterior itself, as well as the posterior segment consisting of PcoA and the segment P1--a. cerebri posterior (PCA) from the a. basilaris bifurcation to the PcoA. For the purpose of grouping the findings, the four basic configuration types of the circle of Willis were identified based on its symmetry or asymmetry. Type-A (symmetric circle of Willis), type-B (asymmetric circle of Willis' due to the unilateral hypoplastic A1-ACA); type-C (symmetric circle of Willis with bilateral symmetric changes on PcoA) and type-D (asymmetric circle of Willis due to the asymmetric changes on PcoA). Autosy was performed on 56 corpses. A total of 41 (73.2%) subjects were recorded with a symmetric configuration of the circle of Willis', of which 27 (48.2%) subjects had type A and 14 (25%) type C. The asymmetric configuration was present in 15 (26.8%) subjects, of whom 9 (16%) had type B and 6 (10.8%) subjects, of whom 9 (16%) had type B and 6 (10.8%) type D. The symmetric Willis group (73.2%) did not have a homogeneous finding that would fit into the schematic presentation of the symmetric type A and type C. A total of 17 (30.4%) findings were classified in this group of the so-called conditionally symmetric configurations. In all the cases, type B (16%) had unilaterally reduced diameter A1 and hyperplastic AcoA. The presence of asymmetric Willis configuration in 26.8% of the cases, which makes up more than one fourth, indicates that the asymmetric configurations do not represent a pathological form of connecting the blood vessels at the base of the brain, but rather one aspect of its adaptation. The forming of the basic types of configurations of the circle of Willis is associated with a tendency toward certain types of hemodynamic disorders and more frequent pathological changes in places of reduced resistance.

Collateral Circulation after Spermatic Vessel Ligation for Abdominal Testis And Its Impact on Staged Laparoscopically Assisted Orchiopexy

Staged laparoscopically assisted orchiopexy for abdominal testis entails initial spermatic vessels ligation followed by mobilization of the testis, preserving the vas and its vessels as a sole source of testicular blood supply. This mobilization includes all peritoneal attachments of the testis, including the gubernaculum, which may carry collateral circulation to the testis. This study considers the anatomy of the gubernaculum and the collateral circulation after spermatic vessels ligation and its possible effects on the viability of the testis. The anatomy of the gubernaculum and the effect of spermatic vessels ligation on the collateral circulation were studied in 90 boys with 100 abdominal testes with a short pedicle. Patients with vanishing testis or those not needing ligation of the spermatic vessels were excluded from the study. The anatomy and the vascularity of the testis, gubernaculum, and vas were studied at initial laparoscopy and 6 weeks later after spermatic vessel ligation. Based on these findings, the technique for laparoscopically assisted orchiopexy were modified, preserving the gubernaculum whenever possible in cases having prominent collaterals. Based on the attachment and blood vessel configuration of the gubernaculum, the patients were divided into two groups: in group 1 (open internal ring), there were 46 testes in which the gubernaculum passed through an open internal ring having an inguinal attachment. In group 2 (closed internal ring), there were 54 testes with a soft gubernaculum attached to a closed internal ring without inguinal attachment. In group 1 the gubernaculum was short and tough in 32 of 46 testes, with no visible blood vessels in all cases. In group 2 the gubernaculum was long and soft in 43 of 54 testes and showing evident blood supply before clipping of the spermatic vessels in 30 testes. Subsequent laparoscopy done after 6 weeks showed prominent collateral circulation around the gubernaculum in 26 testes and around the vas in 20 testes in the group 1 patients, and around the vas in 20 and the gubernaculum in 34 testes in group 2. Preservation of the gubernaculum was possible in 43/54 (80%) of group 2 patients and in 14/46 (30%) of group 1 patients. Routine cutting of the gubernaculum is not necessary for proper mobilization of the abdominal testis: collateral circulation varies from patient to patient, and once the gubernaculum shows prominent blood supply, its preservation is mandatory. The decision to cut the gubernaculum should be taken while the performing initial spermatic vessel ligation and not during the second stage to avoid compromise of the settled collateral circulation.

F-0817 三次元実形状測定システムを用いた動脈分岐部の計算流体力学的解析(S43-5 循環系の数値シミュレーション(2))(S43 生体力学シミュレーション)

The purpose of this study was to investigate the relationship between blood flow and atherosclerosis using Computational Fluid Dynamics. Atherosclerosis is suspected to be related to blood flow, since it develops at specific points on vessel walls. Among these specific locations, bifurcations of blood vessels are especially prone to atherosclerosis, particularly the lateral walls of the common iliac arteries. This distribution of lesions is believed to depend on fluid dynamics phenomena, particularly the wall shear stress. Due to the complex geometry of a real artery, the fine flow structure in an arterial bifurcation may be too complex to study using in vivo or in vitro experiments. Therefore, CFD is one of the most powerful ways to investigate flow in an arterial bifurcation. However, the relevant CFD model must be constructed to obtain a reliable computational analysis. In general, a bifurcation has a complex 3-D configuration, particularly at its sharp edge. Any minute deformation or relative displacement of the bifurcation is thought to have a significant effect on blood flow. In this study, a histology technique, in which the embedded vessels are sliced into thickness of the order of 1 micrometer, was used to model the arterial bifurcation. A computer was used to capture 2-D images of the face of the specimen block after each slice was removed. Then, serial images were used to reconstruct the 3-D blood vessel configuration with a precision appropriate for CFD analysis.

220 三次元血管実形状モデリングシステムを用いた計算流体力学シミュレーション

Atherosclerosis tends to occur at specific sites, including the bifurcation of arteries. An arterial bifurcation has a sharp edge, and therefore a minute deformation or movement can have a strong effect on the blood flow. In order to study the blood flow at bifurcations using a realistic CFD model, the geometry of a three-dimensional blood vessel configuration was reconstructed by cutting the vessel into slices of order of 1 micrometer. A precise CFD model and an experimental flow model were successfully constructed from the obtained data set, using a computer graphics technique and a rapid prototyping method.

1212 三次元血管実形状測定システムの開発と計算流体力学シミュレーション

We studied the relationship between the blood flow and the atherosclerosis using Computational Fluid Dynamics (CFD). Atherosclerosis tends to grow at the bifurcation of abdominal aorta, particularly at the lateral side walls of the common iliac arteries. In general, the bifurcation of blood vessels has a sharp edge, and therefore the minute deformation and movement of the bifurcation are thought to have a large effect on the blood flow. In order to study the blood flow at the bifurcation using realistic CFD model, we developed a modeling system using micrometer thick slicing to reconstruct the 3-dimensional blood vessel configuration for CFD analysis.

Cellular and secretory mechanisms related to delayed radiation-induced microvessel dysfunction in the spinal cord of rats

Purpose : This study aimed to investigate long-term, radiation-induced changes in microvessel permeability, the profile of the vasoactive mediators endothelin and nitric oxide, and the response of specific cell systems in the irradiated spinal cord of rats. Methods and Materials : The thoracolumbar spinal cords of Fischer rats were irradiated to a dose of 15 Gy, and the rats were sacrificed at various times afterward. Endothelin levels and nitric oxide-synthase (NOS) activity were assayed in extracts of spinal cords. Microvascular permeability and the effect of treatment with recombinant human manganese superoxide dismutase (r-hMnSOD) were assessed quantitatively. Immunohistochemistry evaluated astrocytes, microglia, vascular basal membrane, and neurofilaments. Results : None of the rats developed neurologic dysfunction. Endothelin levels were significantly reduced at 18 h after irradiation and markedly attenuated after 10 days ( p < 0.007). Thereafter, endothelin levels returned to normal values at 56 days after radiation and escalated to markedly high levels after 120 and 180 days ( p < 0.002). NOS activity remained very low throughout the period of follow-up and failed to counterbalance the shifts in endothelin levels. Treatment with r-hMnSOD had no effect on normal vascular permeability but it abolished the abnormally increased permeability measured at 18 h after radiation and again after 120 and 180 days. Standard microscopic evaluation failed to reveal abnormalities in the irradiated spinal cord, but immunohistochemical staining showed a progressive increase in the number of microglial cells per field after 120 and 180 days ( p < 0003). A similar increase in the number of astrocytic cells per field was noted after more than 180 days, but an earlier short lasting peak was also noted at 14 days after radiation. No abnormalities were found in blood vessel configuration, density, diameter, and basal membrane staining, or in the neurofilaments. Conclusion : Marked imbalance in the regulatory function of endothelium-derived mediators of the vascular tone is present after radiation therapy probably inducing chronic vasoconstriction. This imbalance favors localized procoagulation that may enhance the consequent loss of function measured as increased permeability. Microglial proliferation may account for continuous release of superoxide that may enhance disruption of normal permeability. The latter is corrected by SOD treatment. Astrocytic proliferation may present a response to the mitogenic effect of endothelin and to microglial-derived paracrine effect of cytokines.

Three‐dimensional blood vessel reconstruction using a high‐speed X‐ray rotational projection system

AbstractThe feature X‐ray angiography is that a blood vessel image with a high spatial resolution is obtained. Consequently, it is a decisive diagnostic tool for the pathology of the blood vessel. However, its precision is still sufficient for the diagnosis of blood vessels with delicate aneurysm or stenosis, as well as for planning surgery. Thus, it is desired to develop further an imaging method for the blood vessel configuration with a higher precision.This paper describes a precise observation method for the blood vessel configuration, where a pair of X‐ray source and the image intensifier (II) with a high‐speed rotation is used to scan and derive multidirectional projection images, and the blood vessel configuration is reconstructed in three‐dimensions for high‐precision 3D observation. As a pre‐processing to the reconstruction, the image distortion correction for II as well as the estimation of the camera coordinate are executed.In the 3D reconstruction of the blood vessel, the filtered backprojection method is used with the short‐scan (details are discussed later) cone‐beam projection. The result of 3D reconstruction of the blood vessel can be observed by the 3D display and the 3D model for the blood vessel configuration. The method is applied to the actual projection image of the cerebral blood vessels, and the effectiveness is demonstrated. By this method, a highly precise measurement of the blood vessel shape is realized, which has not been observed by the past technique, and the configuration of the blood vessel can be analyzed in the 3D space. It is expected that the proposed method with those features will be utilized in the quantitative diagnosis of the cerebral blood vessel diseases and treatment planning.

The blood capillaries in the subodontoblastic region of the human dental pulp, as demonstrated by freeze-fracturing.

The microvasculature of the subodontoblastic region in the human dental pulp was studied, using freeze-fracturing. This technique allows an analysis of the fine structure of the vascular endothelium with special reference to the membrane structure. The blood capillaries were noted to be of the non-fenestrated or continuous type, although a few fenestrated vessels were observed. The endothelial plasmalemma often exhibited bundles of fibrillar structures, presumably myofilaments. There was a relatively large number of micropinocytotic vesicles and the interendothelial spaces were closed juxtaluminally by tight junctions (zonulae occludentes). The junctions appeared mostly as two to four strands, seen as ridges or grooves on the cell membrane. Thin-walled, irregular, tissue channels lacking the typical, blood-vessel configuration were disclosed. These vessels were believed to represent lymphatics.

Changes in the configuration of blood vessels in the frog's submaxillary muscle

Changes in the configuration of blood vessels in the frog's submaxillary muscle