Ein bildgestütztes, funktionelles Verfahren zur optoelektronischen Erfassung der Hautperfusion

Within the scope of this PhD thesis an optoelectronic camera based measurement concept for assessment of skin perfusion (Photoplethysmography Imaging, short PPGI) has been developed. Analogue to the classical PPG variant with skin attached discrete sensors, the fact, that in the visible and near infrared spectrum blood has much higher absorption than surrounding bloodless tissue is utilised. When illuminating the skin with a selective light source, a detector can assess the optical attenuation, which is dependent on the dermal blood volume. By using a highly sensitive camera as a detector advantages over the current state of the art can be achieved - not only non invasive, but also contactless and spatially resolved assessment of the perfusion status of living tissue can be performed. For optimisation of the camera based PPGI sensor concept Monte Carlo simulations have been carried out. They allow the analysis of the interaction processes between incident light and tissue. As one result the observation depth in the skin can be determined. This depth was found to be strongly dependent on the wavelength and can vary from 0.2 mm for the assessment of the micro circulation up to 2mm for measurements of the macro circulation. By using parametrised simulation scenarios a variable blood volume in the skin, i.e. caused by the arterial heart beat, was emulated and thus the detector signal could be predicted by DC- and also AC-component. This allows the evaluation and optimisation of the sensitivity of the measurement system. Due to the contactless measurement principle motion induced artifacts can occur. For the detection and minimisation of these artifacts different strategies for movement compensation have been investigated. Their efficacy has been evaluated on the basis of typical recordings. Signal analysis of the PPGI video sequences can either be done interactively by selecting skin regions for which the time varying optical attenuation and hence the skin perfusion is calculated, or automatic algorithms for the functional mapping can be executed. Here different signal characteristics like amplitude of the heart beat, intensity of vasomotion rhythms, etc. can be calculated for different local regions and displayed spatially resolved in the form of colour coded virtual perfusion maps of the observed skin region. The PPGI system has already been used in several preclinical test and pilot studies and possible applications were explored. These range from basic physiological research over functional diagnostics of the venous system of the lower limbs to arterial diagnostics. The manifold application scenarios include here the contactless monitoring of vital parameters of newborn infants, the assessment and quantification of peripheral perfusion disorders, functional survey of wounds and skin tumors and also the quantification of allergic skin reactions.

Grantor dc:publisher

Publikationsserver der RWTH Aachen University

Year dc:date

2008

Author dc:creator

• Hülsbusch, Markus

Contributors dc:contributor

• Rembold, Bernhard

• info:eu-repo/classification/ddc/620
• Durchblutungsmessung
• Lichtabsorption
• Digitalkamera
• Bewegungskompensation
• Wavelet-Analyse
• Wavelet-Transformation
• Vasomotion
• Mie-Streuung
• Ingenieurwissenschaften
• Photoplethysmographie
• funktionelle Abbildung
• Hautmodell
• Vitalparameter
• skin perfusion
• Photoplethysmography
• Monte Carlo simulation
• functional imaging
• motion compensation

Statement dc:rights

• info:eu-repo/semantics/openAccess

Language dc:language

ger

Identifier

https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-112829%22

OAI record oai:identifier

https://publications.rwth-aachen.de/oai2d?verb=GetRecord&metadataPrefix=oai_dc&identifier=oai%3Apublications.rwth-aachen.de%3A50278