liu.seSearch for publications in DiVA
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Computer assisted video microscopy: in characterization of capillary ensembles
Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
2000 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis focuses on evaluation and analysis of capillary microcirculatory changes in the skin, that can be improved and extended by computer assisted video microscopy. Capillary microscopy has been used extensively, both in clinical practice and research, to study different phenomena in the microvasculature of the skin, mainly in the nailfold of fingers and toes where a large portion of the capillary loop can be observed.

In the majority of the different skin regions, the nutritive capillary network approaches the skin surface perpendicularly and capillary microscopy in these sites reveals the apex of the capillary loop as a dark spot. The main approach in this work has been to study a large ensemble of capillary loops, in order to apply statistical and planar models whilst, at the same time, obtaining spatial parameters related to the capillary localization.

The statistical models of proximity are based on nearest neighbour methods and triangulation techniques. The main reason for introducing these models is because of their capability to characterize the heterogeneity of the capillary ensemble.

A computer assisted video microscopy system, that enables both capturing and evaluating of capillary bed images, was assembled and was, thereafter, successfully used in laboratory and clinical studies.

Place, publisher, year, edition, pages
Linköping: Linköpings universitet , 2000. , 64 p.
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 648
National Category
Medical and Health Sciences
Identifiers
URN: urn:nbn:se:liu:diva-29442Local ID: 14788ISBN: 91-7219-822-2 (print)OAI: oai:DiVA.org:liu-29442DiVA: diva2:250257
Public defence
2000-09-12, Berzeliussalen, Universitetssjukhuset, Linköping, 09:00 (Swedish)
Available from: 2009-10-09 Created: 2009-10-09 Last updated: 2013-02-27
List of papers
1. Microvascular arteriovenous shunting is a probable pathogenetic mechanism in erythromelalgia
Open this publication in new window or tab >>Microvascular arteriovenous shunting is a probable pathogenetic mechanism in erythromelalgia
2000 (English)In: Journal of Investigative Dermatology, ISSN 0022-202X, E-ISSN 1523-1747, Vol. 114, no 4, 643-646 p.Article in journal (Refereed) Published
Abstract [en]

Erythromelalgia is a condition consisting of red, warm, and burning painful extremities. Symptoms are relieved by cold and aggravated by heat. A wide variety of etiologic conditions can cause erythromelalgia, but one common pathogenetic mechanism, microvascular arteriovenous shunting, has been hypothesized. The aim of this study was to test this hypothesis. Quantification of skin microvascular perfusion using laser Doppler perfusion imaging and skin temperature at rest and after central body heating was performed in 14 patients with erythromelalgia and 11 controls. Attacks of erythromelalgia were induced in eight patients after heat provocation. In the plantar region of the foot, the location of numerous anatomical arteriovenous shunts, these patients significantly increased the skin perfusion as compared with asymptomatic patients with erythromelalgia and controls. In the dorsal region with few arteriovenous shunts no significant differences between the groups were demonstrated. The results show a relation between clinical symptoms and increased perfusion in the region of numerous anatomical arteriovenous shunts, and support the hypothesis of increased thermoregulatory arteriovenous shunt flow during attacks in primary erythromelalgia.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-30590 (URN)10.1046/j.1523-1747.2000.00944.x (DOI)16181 (Local ID)16181 (Archive number)16181 (OAI)
Available from: 2009-10-09 Created: 2009-10-09 Last updated: 2017-12-13
2. Imaging, image processing and pattern analysis of skin capillary ensembles
Open this publication in new window or tab >>Imaging, image processing and pattern analysis of skin capillary ensembles
2000 (English)In: Skin research and technology, ISSN 0909-752X, E-ISSN 1600-0846, Vol. 6, no 2, 45-57 p.Article in journal (Refereed) Published
Abstract [en]

Background/aims: The capillary bed is recognized as the site where metabolic and nutrient processes occur for living tissues at all levels. The evaluation of this vital process is a major concern in microcirculation. Unlike traditional approaches that concentrated on the extreme local properties of this process, a more global analysis toward capillary ensembles is employed here, since capillaries work as a cooperative entirety. As a first step toward ensemble analysis, the static and planar geometric parameters are investigated. Parameters such as the capillary adjacency and size information are very important in predicting and analysing certain malfunctions in the microvascular bed.

Methods/results: In order to achieve an objective and accurate analysis of these vital parameters, a computerized imaging system is proposed. Not only the number of capillaries and the capillary cross-sectional areas are important in describing the microvascular bed but the planar distribution pattern of the capillaries also carries valid information. This information, unique to the ensemble analysis, can be used to reveal, visualise and quantify the clustering of capillaries; and this information, according to the Krogh model, is fundamental in estimating the tissue oxygen supply. Two spatial models, the closest neighbor and triangulation methods, have been applied to the captured images of capillary ensembles. The closest neighbor technique generates a minimal distance map or displays a distribution, which depicts the local clustering of capillaries. The triangulation technique, on the other hand, generates a mutual distance map, which is a global description of the capillary positions. Triangulation methods have been evaluated but all except the Greedy triangulation method have been rejected due to lack of robustness and model weakness. Therefore, the capillaries are triangulated by the Greedy triangulation method, and the capillary distribution uniformity is defined as one minus the coefficient of variance of the edge lengths of the mutual distance map.

Conclusions: A series of advanced image processing methods have been developed that efficiently extract the capillary position, size and distribution information from the images. These results facilitate the automatic counting of capillaries and the capillary size-related pathological analysis.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-30588 (URN)10.1034/j.1600-0846.2000.006002045.x (DOI)16179 (Local ID)16179 (Archive number)16179 (OAI)
Available from: 2009-10-09 Created: 2009-10-09 Last updated: 2017-12-13
3. Skin capillary appearance and skin microvascular perfusion due to topical application of analgesia cream
Open this publication in new window or tab >>Skin capillary appearance and skin microvascular perfusion due to topical application of analgesia cream
2000 (English)In: Microvascular Research, ISSN 0026-2862, E-ISSN 1095-9319, Vol. 59, no 1, 14-23 p.Article in journal (Refereed) Published
Abstract [en]

Local topical analgesia changes basal skin perfusion and its regulation. In particular, the response induced by local heating, which in nontreated skin comprises a rapidly increased perfusion followed by a normalization within 30 s, is altered to a delayed and persistent perfusion increase. The response dependency to the analgesia cream application time, that is, the intradermal penetration of the analgesics and in which vascular plexa the response occurs, is not known. The aim of this study was to assess changes in the appearance of superficial skin capillaries and skin microvascular perfusion changes due to different application periods of topical analgesia cream (EMLA). Twelve subjects were treated with EMLA and placebo applied to the volar side of each forearm, respectively. The treatment areas were assigned different application times (20 min, 40 min, 1 h, 2 h, and 3 h). The areas were cleared from the creams and shortly thereafter provoked during 9 s with a probe heated to 45°C. To assess capillary number density and skin perfusion, capillary microscopy, and Laser Doppler perfusion imaging (LDPI), respectively, were used. The number density of physiologically active capillary was significantly decreased with longer application times of EMLA (P < 0.005). The LDPI-signal showed a persistent perfusion increase after provocation associated with increasing application time of the cream. This perfusion pattern was not seen after 20 min of treatment, but was present in 9 of 12 subjects after 3 h of treatment. No significant relationship between changes in the capillary number density and the LDF measurement was found. In conclusion, a longer application time and therefore a higher intradermal concentration and a deeper penetration of the analgesics was associated with a delayed and persistent perfusion increase after local heating. There was a discrepancy between changes in capillary number density and skin perfusion, indicating that the perfusion increase does not occur in the capillaries but in the deeper lying vessels. Hence, the contribution of the capillary perfusion to the LDF-signal is smaller than previously anticipated. Capillary number density and presumably their perfusion were decreased with longer application times.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-30587 (URN)10.1006/mvre.1999.2206 (DOI)16178 (Local ID)16178 (Archive number)16178 (OAI)
Available from: 2009-10-09 Created: 2009-10-09 Last updated: 2017-12-13
4. Computer assisted evaluation of skin capillary density supports the hypothesis of microvascular shunting in erythromelalgia
Open this publication in new window or tab >>Computer assisted evaluation of skin capillary density supports the hypothesis of microvascular shunting in erythromelalgia
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Erythromelalgia subjects often suffer from burning pain in distal parts of the extremities, aggravated by warmth and relieved by cooling. Affected skin is hyperemic and has an increased skin temperature. The shunting hypothesis for the pathogenesis of erythromelalgia, postulates maldistribution of skin microvascular blood flow with increased thermoregulatory flow through arteriovenous shunts and an inadequate nutritive perfusion with a corresponding tissue hypoxia. Our aim was to characterize recruitment and steal distribution changes in affected skin with the aid of an enhanced technique of computer-assisted analysis of capillary beds. This method was used to determine the capillary density before and after central body heating in 14 patients with erythromelalgia and 10 controls. Symptoms were induced in 8 patients and their skin temperature became higher (p<0.05) after central body heating, but the number of visible or active capillaries in the dorsal aspect of the foot decreased significantly, as compared to asymptomatic patients and controls. Since the increased temperature should, normally induce capillary recruitment, and other studies using laser Doppler techniques have shown an increase in global skin perfusion during EM attacks, we conclude that the reduced capillary density shown in this study, is compatible with the hypothesis of blood shunting through AV anastomoses, deep in the dermis.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-89591 (URN)
Available from: 2013-02-27 Created: 2013-02-27 Last updated: 2013-02-27
5. Combined computer assisted capillary microscopy and laser Doppler imaging used to assess redistribution changes in skin of erythromelalgic patients during treatment with misoprostol
Open this publication in new window or tab >>Combined computer assisted capillary microscopy and laser Doppler imaging used to assess redistribution changes in skin of erythromelalgic patients during treatment with misoprostol
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Erythromelalgia is a rare condition defined by red, hot and painful extremities. Warmth intensifies the discomfort while cold provides relief. The clinical picture is heterogeneous with respect to aetiology and severity. We have previously postulated arteriovenous shunting in the skin as a common pathogenetic mechanism. Defects in prostaglandin synthesis, metabolism or functional response have been implicated in the pathogenesis of erythromelalgia. In this pilot study we wanted to describe the skin microcirculation before and after misoprostol treatment, an oral PGE1 analogue.

A non-randomised, placebo-compared study investigating the effect of misoprostol on the skin microcirculation in patients with erythromelalgia using Laser Doppler Perfusion Imaging (LDPI) and Computer Assisted Capillary Microscopy (CACM).

EM was treated with placebo for six weeks followed by misoprostol for the next six weeks. Cutaneous microcirculation was evaluated as determined by the analysis of laser Doppler perfusion imager (global skin perfusion) and computer assisted capillary microscopy (capillary perfusion) before and after whole body heating at baseline, after placebo and misoprostol treatment.

There were a significant increase in skin temperature, global perfusion and reduction in capillary density in non-treated erythromelalgia patients. After misoprostol treatment the changes in the microcirculation are reduced.

The results are consistent with earlier findings of increased global perfusion and reduced capillary density during central body heating. The microcirculatory changes after misoprostol treatment indicate reduced arteriovenous shunting and increased nutritive perfusion.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-89592 (URN)
Available from: 2013-02-27 Created: 2013-02-27 Last updated: 2013-02-27

Open Access in DiVA

No full text

By organisation
Department of Computer and Information ScienceThe Institute of Technology
Medical and Health Sciences

Search outside of DiVA

GoogleGoogle Scholar

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 322 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf