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PubMed2001

[Blood vessels in normal and abnormal mitral valve leaflets].

UNLABELLED: The incidence and the distribution of blood vessels were examined in normal and abnormal mitral valve leaflets. MATERIALS AND METHODS: Normal valves were obtained from 12 autopsy cases without cardiovascular disease (8 men, 4 women, 33 to 93 years of age). Twenty-one abnormal valves were obtained at the time of mitral valve replacement (12 men, 9 women, 16 to 78 years of age). Clinical and pathological diagnoses were rheumatic valvular disease (RVD: n=8), floppy mitral valve (FMV: n=9), and healed infective endocarditis (HIE: n=4, 1 with RVD, 3 with FMV). The number of vessels was counted at the surgical excision line of the valvular rings by immunohistochemical study using Factor VIII related antigen and CD34. Histologic studies were also made at the 5 mm distal line from the ring in normal valves, and at the vertical line to the ring in abnormal valves. RESULTS: In normal valves, the number of vessels at the ring area, except in myocardial tissues that extended from the left atrium to the auricularis, ranged from 3 to 184. Vessels were also found at the 5 mm distal area from the ring in 6 valves out of 12. Vessels were mainly distributed near the commissure areas of the auricularis and/or the spongiosa and were extended with myocardial tissues. There was no difference in the number of vessels related to age or sex. In RVD, the number of vessels at the ring area ranged from 22 to 517 in 8 anterior leaflets (AML) and 2 to 151 in 5 posterior leaflets (PML). Many vessels also appeared in the distal spongiosa of the leaflets, and arterioles were frequently found in these areas. In FMV, a few (3 and 6) vessels were found in 2 leaflets (AML: 2/8, PML: 0/4). In HIE, the number of vessels was 216 in the case with RVD, and 3 to 110 in cases with FMV. CONCLUSION: At the ring area, normal mitral valve leaflets were supplied with nutrition from blood vessels that mainly extended from the left atrium with myocardial tissues. In RVD, the vessels branched from previously existing capillaries, extending to the distal area, and increased in number. Mechanical stress during opening and closing of the leaflets contributes to the arterialization of these vessels. In FMV, the number of capillaries, which is smaller than in normal valves, might be related to the progression of this disorder. In HIE with valvular disease, the number of vessels is related to the preexisting disease.

Adult↗

PubMed2002

[A study of the influence scan timing and depiction of blood vessel diameter in CE-3DMRA: simulation by pulsatile flow].

In imaging using contrast-enhanced three-dimensional magnetic resonance angiography (CE-3DMRA), optimizing the delay time from the start of intravenous injection of contrast medium to the start of scanning has generally been an important concern when obtaining blood vessel images of good contrast. Recent methods of mechanically assessing the attainment of contrast medium injection include Smart-Prep and others. Another method is the Test Bolus, in which a small amount of contrast medium determines the timing of scan start, in quest of the time intensity curve. Because these methods are not necessarily satisfactory, the corrected method is used in clinical cases. In terms of how scan timing affects blood vessel depiction, no study has examined pulsatile flow, which is carried out by simulation. On the other hand, there are reports on data filling of k-space using imitation blood vessels on a computer and simple experimental equipment. This research examined experimentally blood vessel depiction according to scan timing and the diameter of blood vessels by using a systemic circulation simulator that incorporated hemodynamic circulation in which pulsatile flow is the same as that of a human body, using an artificial heart developed especially for MRI. It is thought that scan timing in CE-3DMRA affects the depiction of blood vessels for which the diameter of the blood vessel differs from the experimental result. Phase-encoding k-space data filling is the contrast-to-noise ratio (CNR) of each blood vessel irrespective of sequential and centric k-space ordering. The timing shift phenomenon, in which a blood vessel is so thin that the scan timing is overdue and shows a relatively high value, can occur. Moreover, that scan timing affects not only the diameter of a blood vessel but also depiction of the narrowing of a stenotic blood vessel or a branch blood vessel was demonstrated clinically and experimentally. Therefore, blood vessel depiction changes with scan timing, and it is clinically important to determine the time of arrival of contrast medium and the duration of the enhancement effect in quest of the time intensity curve by test bolus when clearly describing the target blood vessel.

Blood Vessels↗

PubMed2004

Large vessel involvement in ANCA-associated vasculitides: report of a case and review of the literature.

Vasculitides are currently classified according to the size of the vessels involved and characteristic clinical and histopathologic findings. Antineutrophil cytoplasmic antibodies (ANCA) and other serologic tests have been used to further characterize small vessel vasculitides. Large vessel involvement in ANCA-associated small vessel vasculitides has been overlooked in the medical literature. Here, we report a case of fatal aortitis and aortic dissection in a patient with microscopic polyangiitis and review reported cases of large vessel involvement in ANCA-associated vasculitides since 1990. We have attempted to characterize this subgroup of patients. Large vessel disease in ANCA-associated vasculitis may present as stenosing large vessel arteritis, aneurysmal disease, aortic dissection, aortic rupture, aortic regurgitation, and death. Prominent perivascular inflammation may present as mediastinal, cervical or abdominal soft tissue masses. ANCA-associated large vessel disease should be considered in the differential diagnosis of these disorders. The epidemiologic, clinical and pathologic characteristics of these patients differ from those of the well-defined large vessel vasculitides such as giant cell (temporal) arteritis or Takayasu's arteritis. We suggest that large vessel involvement is part of the spectrum of ANCA-associated vasculitis rather than an overlap with other large vessel vasculitides. It occurs in both myeloperoxidase- and proteinase 3-positive patients with either Wegener's granulomatosis or microscopic polyangiitis, but has not been reported in Churg-Strauss syndrome. Large vessel vasculitis can precede small vessel vasculitis or occur in the absence of small vessel involvement. We hope this report will contribute to the ongoing development of classification systems for the vasculitic syndromes.

Aortic Dissection↗

PubMed2006

Vessel ultrastructure in APP23 transgenic mice after passive anti-Abeta immunotherapy and subsequent intracerebral hemorrhage.

Passive immunization of amyloid precursor protein (APP) transgenic mice with anti-amyloid beta (Abeta) antibodies was shown to reduce Abeta-deposition in brain and to improve cognition. However, immunotherapy may also be accompanied by a significant increase in the frequency of intracerebral hemorrhages. Because hemorrhages are associated with amyloid-laden vessels, this raises the question whether high concentrations of anti-Abeta antibodies may directly or indirectly lead to a structural destabilization of the vessel wall. To address this point, transmission electron microscopy was performed and the ultrastructure of bleeding and non-bleeding vessels in immunized and non-immunized APP23 transgenic animals was analyzed. To localize bleeding vessels, hemosiderin-positive macrophages were visualized by pre-embedding Perl's Berlin Blue histochemistry. Vessels were analyzed morphologically, anomalies evaluated and quantified. Bleeding vessels were, furthermore, reconstructed in three dimensions to analyze the spatial distribution of amyloid deposits and other pathological changes of the vessel wall. This in-depth morphological analysis revealed that bleeding vessels in immunized as well as in non-immunized APP23 mice were surrounded by a higher number of macrophages compared to non-bleeding vessels in the same animals. However, no differences in the number of macrophages or other structural parameters, such as amyloid deposition, were observed between bleeding vessels of immunized and non-immunized mice. No pathologies which may indicate impending bleeding were observed in the vascular wall of non-bleeding vessels. We conclude, that the increased hemorrhage frequency observed after passive immunization with anti-Abeta antibodies does not lead to overt structural changes in the vessel wall of APP23 transgenic mice. Minor structural alterations of the vessel wall, however, cannot be excluded due to the sample size of our study and the high complexity of the three-dimensional vessel wall ultrastructure.

Alzheimer Disease↗

PubMed1999

An in-vitro evaluation of aortic arch vessel perfusion characteristics comparing single versus multiple stream aortic cannulae.

OBJECTIVE: During extracorporeal circulation design and orientation of aortic cannulae tips mainly determine flow pattern in the aortic arch and arch vessels which is the objective of this in vitro study, comparing single versus multiple stream cannulae. METHODS: In an aortic arch glass model, jet streams of 21-24 French aortic cannulae which were inserted in the ascending aorta were directed alternatively at the different arch vessels. Flows and pressures in the arch vessels were measured at pump flows of 3-6 l/min. RESULTS: With optimal orientation of the jet stream in the aortic arch, no preferential flow in the arch vessels was seen. In the single jet stream aortic cannulae group a significant parallel increase in flow and pressure in the jet streamed arch vessels compared to the non-jet streamed arch vessels occurred (P < 0.05). With the jet stream directed on vessel 2 (left carotid vessel) there was a significant pressure and flow difference comparing the two non-jet streamed vessels with each other (P < 0.03). In the single stream 24 French cannulae the highest vessel pressure of 168 mmHg and an increase in flow of 186 ml/min was measured in the jet streamed left carotid artery at 6 l/min pump flow. The multiple stream cannulae provoked the highest vessel pressure of 106 mmHg in the corresponding jet streamed vessel and an increase in flow of 20 ml/min. CONCLUSION: Tip design of aortic cannulae and the orientation of its jet stream are potential sources of remarkable imbalance of arch vessel perfusion especially with single jet stream cannulae. These effects are more pronounced with single jet stream cannulae. These results may have important clinical implications regarding perfusion of arch vessels during extracorporeal circulation.

Aorta, Thoracic↗

PubMed1997

The visible vessel on the bleeding gastric ulcer: an endoscopic-pathological study.

BACKGROUND AND STUDY AIMS: The visible vessel is an important endoscopic sign for predicting rebleeding in ulcers. Freeman has described a visible vessel with a high rate of rebleeding as a "pearl" color (whitish) compared with a darkly colored "sentinel" clot with a low rebleeding rate. Clarifying the color of visible vessels helps to distinguish high-risk bleeding ulcers. We conducted a retrospective study that compared pathological findings with endoscopic pictures to determine the significance of the visible vessel's color. PATIENTS AND METHODS: From January 1986 to December 1992, 110 patients who underwent endoscopy and received subtotal gastrectomies for ulcer bleeding were included in this study. Of these, 24 received endoscopic therapy before the operation. There were 94 males and 16 females, ranging in age from 30 to 90 years, with a mean age of 62.5 years. According to Freeman's report, a subgroup of visible vessels (IIav +) was defined as having either a "pearl-colored" collar around a red or black protruding mount or a "pearl-colored" mount on the ulcer base. The endoscopic findings were compared with the findings of the pathological specimens. RESULTS: The endoscopic findings on the stigmata of recent hemorrhage in the 110 patients revealed that 31 were of type IIa (including 18 type IIav+ and 13 type IIav-), 56 of type IIb, 18 of type IIc, and 5 of type III. Fifty-four patients (49,1%) were found from their pathological specimen to have an eroded vessel on their ulcer base. Type IIa patients had a higher percentage of eroded vessels. The percentages of eroded vessels in types IIa, IIb, IIc, and III were 67.7%, 46.4%, 33.3%, and 20 %, respectively (P < 0.05, Fisher's exact test). Of the 54 patients with an eroded vessel in their pathological specimen, 13 (24 %) were found to have some vessel wall above the ulcer base (six in type IIa, four in type IIb, two in type IIc, and one in type III). Among the six with vessel wall above the ulcer base in type IIa, five patients (83 %) were identified as type IIav+ under endoscopy. There was a greater frequency of having a vessel wall above the ulcer base in type IIav+ than in type IIav- (38.5% vs. 12.5%) among the 31 endoscopic type IIa patients. CONCLUSION: From this study, we determined that the wall of an eroded vessel on a gastric ulcer may protrude either above or below the ulcer base. A vessel wall on the ulcer base will appear pearl-colored under endoscopic view.

Female↗

PubMedDate not supplied

Surgical approaches to recipient vessels of the head and neck for microvascular free tissue transfer in dogs.

OBJECTIVE: To develop and evaluate surgical approaches to the arteries and veins of the head and neck for use as potential recipient vessels for free tissue transfer. STUDY DESIGN: Experimental anatomic study. SAMPLE POPULATION: Eleven canine cadavers; 2 preserved cadavers and 9 fresh cadavers. METHODS: The head and neck of one preserved cadaver injected with pigmented silicone/barium, through the common carotid artery and external jugular vein, was cut in 1 cm sagittal sections and cross-sections. These tissue sections were used to identify the location of recipient vessels >1 mm that could be used as recipient vessels for free tissue transfer. The other preserved cadaver was used to develop surgical approaches to these vessels. Three board certified surgeons evaluated the written descriptions and illustrations of the approaches using fresh cadavers. Modifications to the surgical approaches were made based on recommendations from these surgeons. RESULTS: Seven approaches were developed to isolate recipient vessels of the head and neck region. The infraorbital, temporal, and sublingual approaches were easily performed and provided excellent access to the vessels in the region. The approach to the caudal auricular vessels was found to be more difficult but modification of the approach resolved this problem. Access to the facial artery was difficult; it was consistently <1 mm in diameter and thus its use could not be recommended. The approach to the vessels in the cervical region was easily performed. Because of the large size of the external jugular vein and the common carotid artery, end-to-side anastomosis of the donor to recipient vessels is necessary. The large superficial cervical vessels were easily accessed by a lateral shoulder approach. CONCLUSIONS: Surgical approaches to potential recipient vessels of the head and neck were consistently achieved and provided relatively easy access to the vessels. Clinical Relevance- The surgical approaches described in this report can be used to isolate arteries and veins of the head and neck that are >1 mm in diameter. These vessels are suitable for use as recipient vessels for free tissue transfer for reconstruction of complex wounds of the head and neck.

Anastomosis, Surgical↗

PubMed1998

A randomised controlled comparison of injection, thermal, and mechanical endoscopic methods of haemostasis on mesenteric vessels.

BACKGROUND AND AIMS: A randomised controlled comparison of haemostatic efficacy of mechanical, injection, and thermal methods of haemostasis was undertaken using canine mesenteric vessels to test the hypothesis that mechanical methods of haemostasis are more effective in controlling haemorrhage than injection or thermal methods. The diameter of arteries in human bleeding ulcers measures up to 3.45 mm; mesenteric vessels up to 5 mm were therefore studied. METHODS: Mesenteric vessels were randomised to treatment with injection sclerotherapy (adrenaline and ethanolamine), bipolar diathermy, or mechanical methods (band, clips, sewing machine, endoloops). The vessels were severed and haemostasis recorded. RESULTS: Injection sclerotherapy and clips failed to stop bleeding from vessels of 1 mm (n = 20) and 2 mm (n = 20). Bipolar diathermy was effective on 8/10 vessels of 2 mm but failed on 3 mm vessels (n = 5). Unstretched elastic bands succeeded on 13/15 vessels of 2 mm but on only 3/10 vessels of 3 mm. The sewing machine achieved haemostasis on 8/10 vessels of 4 mm but failed on 5 mm vessels (n = 5); endoloops were effective on all 5 mm vessels (n = 5). CONCLUSIONS: Only mechanical methods were effective on vessels greater than 2 mm in diameter. Some mechanical methods (banding and clips) were less effective than expected and need modification. Thermal and (effective) mechanical methods were significantly (p < 0.01) more effective than injection sclerotherapy. The most effective mechanical methods were significantly more effective (p < 0.01) than thermal or injection on vessels greater than 2 mm.

Animals↗

PubMed1997

Local staging of pancreatic cancer: criteria for unresectability of major vessels as revealed by pancreatic-phase, thin-section helical CT.

OBJECTIVE: This study was conducted to determine the criteria for unresectability of major peripancreatic vessels in patients with pancreatic carcinoma as revealed by optimally enhanced, pancreatic-phase thin-section helical CT. SUBJECTS AND METHODS: Twenty-five patients with pancreatic adenocarcinoma who underwent local dissection during curative or palliative surgery also underwent preoperative pancreatic-phase thin-section helical CT (40- to 70-sec delay, 2.5- to 3-mm collimation). Tumor involvement of the portal and superior mesenteric veins and the celiac, hepatic, and superior mesenteric arteries was prospectively graded on a 0-4 scale based on circumferential contiguity of tumor to vessel. Subsequent surgical results were then correlated with the CT grades. RESULTS: At surgery, definitive evaluation was possible for 80 vessels. Forty-eight of 48 vessels graded 0 and three of three vessels graded 1 were resectable. Four of seven vessels graded 2, seven of eight vessels graded 3, and 14 of 14 vessels graded 4 were unresectable. A threshold of between grades 2 and 3, which corresponded to tumor involvement of one-half circumference of the vessel, yielded the lowest number of false-negatives and an acceptable number of false-positives for unresectability. Such a threshold would have yielded a sensitivity of 84%, a specificity of 98%, a positive predictive value of 95%, and a negative predictive value of 93% for unresectability of the vessels studied. CONCLUSION: A grading system for tumor involvement of the major vessels in patients with pancreatic adenocarcinoma can be based on the degree of circumferential contiguity of tumor to vessel. Involvement of vessel to tumor that exceeds one-half circumference of the vessel is highly specific for unresectable tumor.

Adenocarcinoma↗

PubMed2003

Nucleolar organizer regions (NORs). Their significance in the determination of the origin of the lymphoid vessels.

AIM: The aim of this study is the evaluation of the cellular activity of the embryonal mesenchyme in order to investigate if the primitive lymph vessels are derived from clefts of the mesenchyme or from capillary offshoots from the endothelium of the veins. For this reason we applied the quantitative estimation of nucleolar organizer regions (NORs) in the endothelial cells of the lymph and blood vessels, as well as in the mesenchymal cells that surround these vessels. METHODS: Our material consisted of the histological sections from the proper mesenterium of 30 embryos in different stages of development (10th, 12th, 15th, 20th, 23th and 30th week). RESULTS: A statistically significant difference in the average AgNORs value in the endothelial (ANOVA, p<0.0001) and the mesenchymal cells (ANOVA, p<0.0001) between lymph vessels, blood vessels at close and blood vessels at distant regions (10th, 12th, 15th week) was found. There was no statistically significant difference of the average AgNORs value in the endothelial (ANOVA, p=0.55) and the mesenchymal cells (ANOVA, p=0.49) between lymph vessels, blood vessels at close and blood vessels at distant regions (20th, 23th, 30th week). CONCLUSION: The above results suggest that the development of the lymph vessels follows that of the blood vessels. Furthermore, the intense protein synthesis that is expressed by means of NORs in the mesenchymal cells surrounding lymph vessels from the 10th to the 15th week of development is an additional proof of the view that the primitive lymph vessels are derived from clefts into the embryonal mesenchyma and not from capillary offshoots of the endothelium of the blood vessels.

Gestational Age↗

PubMed1996

Light distributions in a port wine stain model containing multiple cylindrical and curved blood vessels.

BACKGROUND AND OBJECTIVES: Knowledge of the light distribution in skin tissue is important for the understanding, prediction, and improvement of the clinical results in laser treatment of port wine stains (PWS). The objective of this study is to improve modelling of PWS treated by laser using an improved and more realistic PWS model. STUDY DESIGN/MATERIALS AND METHODS: Light distributions are calculated by the Monte Carlo method for various PWS blood vessel configurations, such as single and multiple vessels oriented horizontally, curved vessels, and "vertically" oriented vessels. Various vessel sizes and wavelengths are used. RESULTS: Our modelling confirms the concept of selective photothermolysis; 577nm laser light gives maximal deposited energy at the top side of the blood vessels closest to the skin surface and 585nm gives a more uniform energy distribution in the vessel. In the distribution of deposited energy multiple vessels mutually influence each other, because of "shadowing" of diffuse light. CONCLUSION: Modelling PWS laser treatments with multiple vessels confirms the need for successive treatments of vessels layer by layer. The use of different wavelengths affects the local deposited energy profiles in the blood vessels. It predicts that the significance of 585nm laser light lies in the uniform energy distribution in the vessels rather than in gain in energy deposition with depth. The calculated light distributions provide a more realistic input for modelling thermal damage effects in PWS laser treatment and modelling of the epidermal response in thermal imaging of the PWS blood vessel structure.

Blood Vessels↗

PubMedDate not supplied

Effects of off-centering on dose uniformity along and around blood vessels undergoing catheter-based intravascular brachytherapy.

PURPOSE: In intravascular brachytherapy, either photon or beta emitters are often used in a linear arrangement so that blood vessels of lengths in the range of several centimeters can be treated. With a line source, the dose uniformity and the range of doses that various components of the blood vessels receive depend not only on the type of radionuclides used in the treatment but also on the geometric position of radioactive source relative to the blood vessel walls. The aim of this study is to investigate the dose uniformity around the blood vessel and the effects on the uniformity due to the changes of the off-centering of different photon and beta emitters within the lumen. MATERIALS AND METHODS: Dose distributions were calculated on a cylindrical blood vessel of various radii. The radioactive sources of (192)Ir, (125)I, (103)Pd, (188)Re, (32)P, and (90)Y/Sr were studied. All the sources were assumed to be in the form of a line and had a length of 2 cm. The dose rate at a point in space produced by a radioactive source was computed by integrating the point dose rate kernel of the corresponding radionuclide over the 2-cm-long radioactive line. The point dose rate kernel was computed with Monte Carlo simulation of radiation transport. Dosimetric calculations were performed for both concentric and nonconcentric radioactive line source locations. Off-centering effects on the dosimetry were characterized with two newly defined quantities LDU and ADU: LDU describes the longitudinal dose uniformity along blood vessels and ADU describes the azimuthal dose uniformity, i.e., the dose deviation from the expected delivery dose around blood vessels. RESULTS: The longitudinal dose uniformity did not change significantly with the off-center distance. The azimuthal dose uniformity around the blood vessel deteriorated as the off-center distance increased. The ADU was worse for nonconcentric beta emitters than the photon emitters. For example, if the off-center distance was 1 mm and the radial distance was 1.5 mm, the range of dose around the blood vessel on the central transverse plane (normalized to the corresponding dose under the concentric condition) was from 0.55 to 3.3, 0.56 to 3.3, 0.53 to 3.4, 0.43 to 6.0, 0.38 to 4.3, and 0.31 to 4.7 for (192)Ir, (125)I, (103)Pd, (90)Y/Sr, (188)Re, and (32)P sources, respectively. However, it appeared that there existed a lower limit of underdosing (about 40% of desired delivery dose) caused by the off-centering for the photon emitters. It was also found that both ADU and LDU became almost independent of source length when the length was longer than or equal to 20 mm. CONCLUSIONS: A generalized formalism for expressing the dose uniformity along and around blood vessels generated with a linear source was developed and used to study the longitudinal and azimuthal dose uniformity for different types of radionuclides. Although concentric beta emitters provide uniform dose coverage along blood vessels, nonconcentric beta emitters produced larger dose deviations and worse dose uniformity around the blood vessels than photon emitters. The off-centering introduced significantly higher dose on proximal vessel walls for both beta and photon emitters; however, the underdosing at distal points due to off-centering was somewhat limited for the high-energy photon emitters. The magnitude of off-centering effects for the low-energy photon emitters ((103)Pd) was less than that for beta emitters but more than that for higher energy photon emitters ((125)I and (192)Ir).

Beta Particles↗

PubMed2000

[Intracoronary stents in small vessels: short- and long-term clinical results].

OBJECTIVE: To assess the clinical outcome of coronary stenting in small vessels (< 3 mm), using high pressure balloon inflation and antithrombotic therapy. PATIENTS AND METHODS: Vessel size was evaluated as < or >= 3 mm at the time of procedure and measured at a level of maximum diameter. We studied 234 consecutive patients with placement of 300 stents in 279 lesions, comprising 84 stents implanted in 79 lesions located at small vessels (< 3 mm). The standard technique included high pressure balloon inflation (15.8 +/- 2.2 atm) and post-stenting therapy with ticlopidine and aspirin for one month. Mean clinical follow-up was 17.6 +/- 10 months. RESULTS: Procedural success without in-hospital major events was similar between small and large vessels (93.7 in vessels of < 3 mm vs 93.5% in vessels of >= 3 mm; p = NS). Three small vessels presented subacute stent thrombosis, whereas no thrombotic occlusion occurred in large vessels (3.8 vs 0%; p = 0.006). At two years, small vessels had a lower target lesion revascularization free survival (73.6 vs 90.3%; p < 0.001). After adjustment for variables previously described as predictors of stent restenosis, in multivariate analysis, a small vessel of < 3 mm was an independent predictor of target lesion revascularization (p = 0.001). Although patients with stenting in small vessels did not differ significantly in terms of any cause death (4.6 vs 3.8%; p = 0.7) nor acute myocardial infarction (2.9 vs 1.1%; p = 0.3), event-free survival was significantly lower after two years (69.1 vs 86.6%; p < 0.001). CONCLUSIONS: As compared to large vessels, coronary stenting in small vessels was performed with similar rates of initial success, however they had a significantly worse clinical long-term outcome in terms of subacute stent thrombosis and target lesion revascularization at follow-up.

Adult↗

PubMed1996

A description of discrete vessel segments in thermal modelling of tissues.

In hyperthermia treatment planning vessels with a diameter larger than 0.5 mm must be treated individually. Such vessels can be described as 3D curves with associated diameters. The temperature profile along the vessel is discretized one dimensionally. Separately the tissue is discretized three dimensionally on a regular grid of voxels. The vessel as well as the tissue are positioned in one global space. Methods are supplied to describe the tissue-vessel interaction, the shift of the blood temperature profile describing the flow of blood along the vessel and the calculation of the vessel wall temperature. The calculation of the interaction is based on tissue temperature samples and the blood temperature together with the distance between the centre of the vessel and the tissue temperature sample. An analytical expression for a vessel inside a coaxial tissue cylinder is then used for the calculation of the heat flow rate across the vessel wall. The basic test system is a vessel segment embedded inside a coaxial tissue cylinder. All the tests use this setup while the following simulation parameters are varied: position and orientation of the vessel relative to the tissue grid, vessel radius, sample density of the blood temperature and power deposition inside the tissue cylinder. The blood temperature profile is examined by calculation of the local estimate of the equilibration length. All tests show excellent agreement with the theory.

Biophysical Phenomena↗

PubMed2006

Retinal vessel centerline extraction using multiscale matched filters, confidence and edge measures.

Motivated by the goals of improving detection of low-contrast and narrow vessels and eliminating false detections at nonvascular structures, a new technique is presented for extracting vessels in retinal images. The core of the technique is a new likelihood ratio test that combines matched-filter responses, confidence measures and vessel boundary measures. Matched filter responses are derived in scale-space to extract vessels of widely varying widths. A vessel confidence measure is defined as a projection of a vector formed from a normalized pixel neighborhood onto a normalized ideal vessel profile. Vessel boundary measures and associated confidences are computed at potential vessel boundaries. Combined, these responses form a six-dimensional measurement vector at each pixel. A training technique is used to develop a mapping of this vector to a likelihood ratio that measures the "vesselness" at each pixel. Results comparing this vesselness measure to matched filters alone and to measures based on the Hessian of intensities show substantial improvements, both qualitatively and quantitatively. The Hessian can be used in place of the matched filter to obtain similar but less-substantial improvements or to steer the matched filter by preselecting kernel orientations. Finally, the new vesselness likelihood ratio is embedded into a vessel tracing framework, resulting in an efficient and effective vessel centerline extraction algorithm.

Algorithms↗

PubMed1997

Bronchial blood vessel dimensions in asthma.

The extent to which the bronchial vasculature contributes to airway wall thickening in large and small airways in patients with asthma is unknown. The aim of this study was to quantify the number and the area occupied by blood vessels in the airway submucosa of patients with and without asthma. We used the monoclonal antibody Factor VIII to measure the blood vessels between the airway basement membrane and the outer border of the smooth muscle. In large cartilaginous airways in patients with fatal asthma, the number and area of large blood vessels were increased and the number and area of small blood vessels were decreased, compared with that in patients with nonfatal asthma and control subjects. However, the total number of blood vessels and the total area occupied by blood vessels per square millimeter in the airway submucosa were similar in patients with fatal asthma or nonfatal asthma and in control subjects in all airway size groups. Blood vessels were distended to a mean value of 80% of their estimated maximal area. The increased number of larger vessels in patients with fatal asthma raises the possibility that vascular congestion associated with an acute severe asthma attack may distend blood vessels. The finding of similar numbers of blood vessels per square millimeter of submucosa in control subjects and in patients with asthma suggests that blood vessels increase in number in patients with asthma only in proportion to increased airway wall area. It is unlikely that submucosal vessels could act as capacitance vessels and significantly alter inner airway wall thickness.

Adult↗

PubMed1997

Application of thrombin based fibrin glue and non-thrombin based batroxobin glue on intact human blood vessels: evidence for transmural thrombin activity.

An alternative method of uniting small diameter vessels to obtain tissue union while limiting the thrombogenic effect of suture placement at a vessel anastomosis involves the use of a thrombin based fibrin glue as a surgical sealant. This investigation addresses whether the in vitro application of a thrombin based glue (TG), or batroxobin glue (BG), a non-thrombin based glue made with the snake venom enzyme batroxobin, alters intravascular platelet deposition (PD) or cleaves blood fibrinogen, as measured by fibrinopeptide A (FPA) production, when the respective glue is applied to the external surface of an intact human placental artery or an artery with an anastomosis. When TG was applied to the adventitial surface of an intact vessel or an anastomosis (n = 7) of control and experimental vessels, there was a significant increase in intraluminal platelet deposition, an effect not realized with BG (n = 12, intact vessel TG p = 0.01, BG p = 0.66, anastomosis TG p <0.01, BG p <0.01). Both TG and BG significantly increased FPA levels when human whole blood was perfused through both intact vessels or vessels containing an anastomosis when compared to control vessels (intact vessel TG and BG p <0.01, anastomosis TG and BG p <0.01). Labelled thrombin studies document the rapid passage of thrombin through an intact vessel wall or vessels with an anastomosis when TG was applied to the adventitial surface of the vessel. The data suggest that TG and BG are drug delivery systems for their respective enzymes that either pass through or transfer a message across not only a surgically created anastomosis, but also an intact vessel wall.

Batroxobin↗

PubMed2005

Analyzing attributes of vessel populations.

Almost all diseases affect blood vessel attributes (vessel number, radius, tortuosity, and branching pattern). Quantitative measurement of vessel attributes over relevant vessel populations could thus provide an important means of diagnosing and staging disease. Unfortunately, little is known about the statistical properties of vessel attributes. In particular, it is unclear whether vessel attributes fit a Gaussian distribution, how dependent these values are upon anatomical location, and how best to represent the attribute values of the multiple vessels comprising a population of interest in a single patient. The purpose of this report is to explore the distributions of several vessel attributes over vessel populations located in different parts of the head. In 13 healthy subjects, we extract vessels from MRA data, define vessel trees comprising the anterior cerebral, right and left middle cerebral, and posterior cerebral circulations, and, for each of these four populations, analyze the vessel number, average radius, branching frequency, and tortuosity. For the parameters analyzed, we conclude that statistical methods employing summary measures for each attribute within each region of interest for each patient are preferable to methods that deal with individual vessels, that the distributions of the summary measures are indeed Gaussian, and that attribute values may differ by anatomical location. These results should be useful in designing studies that compare patients with suspected disease to a database of healthy subjects and are relevant to groups interested in atlas formation and in the statistics of tubular objects.

Cerebral Arteries↗