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A diffuse reflectance spectroscopic study of UV-induced erythematous reaction across well-defined borders in human skin
Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska högskolan.
Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska högskolan.
Linköpings universitet, Institutionen för klinisk och experimentell medicin, Dermatologi och venerologi. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Hjärt- och Medicincentrum, Hudkliniken i Östergötland.
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2010 (Engelska)Ingår i: Skin research and technology, ISSN 0909-752X, E-ISSN 1600-0846, Vol. 16, nr 3, s. 283-290Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Introduction The colour of tissue is often of clinicaluse in the diagnosis of tissue homeostasis andphysiological responses to various stimuli.Determining tissue colour changes and borders,however, often poses an intricate problem and visualexamination, constituting clinical praxis, does notallow them to be objectively characterized orquantified. Demands for increased inter- and intraobserverreproducibility have been incentives for theintroduction of objective methods and techniques fortissue colour (e.g. erythema) evaluation. The aim ofthe present paper was to study the border zone of anUVB provoked erythematous response of humanskin in terms of blood volume and oxygenationmeasured by means of diffuse reflectancespectroscopy using a commercial probe.

Material and Methods A provocation model, basedon partial masking of irradiated skin areas, definestwo erythema edges at every skin site responding tothe UV irradiation. In every subject, 5 test sites wereexposed with a constant UV light irradiance (14mW/cm2), but with different exposures times (0, 3,6, 9, 12 seconds). An analysis of the spectral datameasured across the two edges was performed for every scan line. The oxygenized and deoxygenizedhemoglobin contents were estimated in everymeasurement point, using a modified Beer-Lambertmodel.

Results The fit of the experimental data to the model derived by the modified Beer-Lambert law was excellent (R2>0.95). Analyzing data for the chromophore content showed that the erythematous response in provoked areas is dominated by the increase in oxyhemoglobin. The width for the left and right border zone was estimated to 1.81±0.93 mm and 1.90±0.88 mm respectively (M±SD). The unprovoked area between the two edges was estimated to 0.77±0.68 mm.

Conclusion While the chosen data analysis performed satisfactory, the ability of the probe design to differentiate spatial aspects of a reaction with abrupt borders was found to be suboptimal resulting in a probable overestimation of the erythematous edge slope. Probe modification or imaging are possible solutions.

Ort, förlag, år, upplaga, sidor
Wiley , 2010. Vol. 16, nr 3, s. 283-290
Nyckelord [en]
Erythema, UV, Spectroscopy, Oxygenation, Human skin
Nationell ämneskategori
Biomedicinsk laboratorievetenskap/teknologi
Identifikatorer
URN: urn:nbn:se:liu:diva-15185DOI: 10.1111/j.1600-0846.2010.00424.xOAI: oai:DiVA.org:liu-15185DiVA, id: diva2:113598
Tillgänglig från: 2008-10-22 Skapad: 2008-10-22 Senast uppdaterad: 2017-12-14Bibliografiskt granskad
Ingår i avhandling
1. In Vivo Diffuse Reflectance Spectroscopy of Human Tissue: From Point Measurements to Imaging
Öppna denna publikation i ny flik eller fönster >>In Vivo Diffuse Reflectance Spectroscopy of Human Tissue: From Point Measurements to Imaging
2008 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

This thesis presents the non-invasive use of diffuse reflectance spectroscopy (DRS) to provide information about the biochemical composition of living tissue. During DRS measurements, the incident, visible light is partially absorbed by chromophores but also scattered in the tissue before being remitted.

Human skin and heart, the main tissue objects in this thesis, are dependent on a sufficient inflow of oxygenized blood, and outflow of metabolic byproducts. This process could be monitored by DRS using the spectral fingerprints of the most important tissue chromophores, oxyhemoglobin and deoxyhemoglobin.

The Beer-Lambert law was used to produce models for the DRS and has thus been a foundation for the analyses throughout this work. Decomposition into the different chromophores was performed using least square fitting and tabulated data for chromophore absorptivity.

These techniques were used to study skin tissue erythema induced by a provocation of an applied heat load on EMLA-treated skin. The absorbance differences, attributed to changes in the hemoglobin concentrations, were examined and found to be related to, foremost, an increase in oxyhemoglobin.

To estimate UV-induced border zones between provoked and nonprovoked tissue a modified Beer-Lambert model, approximating the scattering effects, was used. An increase of chromophore content of more than two standard deviations above mean indicated responsive tissue. The analysis revealed an edge with a rather diffuse border, contradictory to the irradiation pattern.

Measuring in the operating theater, on the heart, it was necessary to calculate absolute chromophore values in order to assess the state of the myocardium. Therefore, a light transport model accounting for the optical properties, and a calibrated probe, was adopted and used. The absolute values and fractions of the chromophores could then be compared between sites and individuals, despite any difference of the optical properties in the tissue.

A hyperspectral imaging system was developed to visualize the spatial distribution of chromophores related to UV-provocations. A modified Beer-Lambert approximation was used including the chromophores and a baseline as an approximate scattering effect. The increase in chromophore content was estimated and evaluated over 336 hours.

In conclusion, advancing from a restricted Beer-Lambert model, into a model estimating the tissue optical properties, chromophore estimation algorithms have been refined progressively. This has allowed advancement from relative chromophore analysis to absolute values, enabling precise comparisons and good prediction of physiological conditions.

Ort, förlag, år, upplaga, sidor
Linköping: Linköping University Electronic Press, 2008. s. 88
Serie
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1210
Nationell ämneskategori
Medicinsk laboratorie- och mätteknik
Identifikatorer
urn:nbn:se:liu:diva-15191 (URN)978-91-7393-809-9 (ISBN)
Disputation
2008-10-31, Elsa Brändströmsalen, Södra entrén, Campus US, Universitetssjukhuset, Linköpings universitet, Linköping, 09:00 (Engelska)
Opponent
Handledare
Tillgänglig från: 2008-10-22 Skapad: 2008-10-22 Senast uppdaterad: 2009-04-30Bibliografiskt granskad

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