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Optical non-invasive technique for vessel imaging: I. Experimental results
Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
2000 (English)In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 45, no 12, 3765-3778 p.Article in journal (Refereed) Published
Abstract [en]

This paper investigates some prerequisites for vessel imaging based on diffuse reflectance measurements in order to develop an optical non-invasive method for the imaging and monitoring of vessels.

The method utilizes near-infrared (NIR) radiation (890 nm) from a light emitting diode. The light is guided into the tissue via an optical fibre (diameter 1.0 mm). The backscattered light is collected by an optical fibre of the same type and detected by an optical power meter. The fibres are moved over the skin in two directions with the aid of two motors operated by a microcomputer. Spatially resolved reflectance at the skin surface could be presented as a vessel-map in a colour-coded form on a computer screen.

Experimental results indicate that the vessel imaging facility depends upon source-detector separation, relative position and vessel depth, and does not depend essentially on the radiant power from the light source. It is shown that, by a proper choice of probe parameters, one can improve the vessel identification ability.

After vessel imaging the technique can potentially be used to monitor several physiological parameters on a selected vascular bed or to distinguish between injured and healthy tissue by monitoring local blood flow, oxygen saturation and the recirculation, pre- and post-operatively.

Place, publisher, year, edition, pages
2000. Vol. 45, no 12, 3765-3778 p.
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:liu:diva-54930DOI: 10.1088/0031-9155/45/12/318OAI: oai:DiVA.org:liu-54930DiVA: diva2:311695
Available from: 2010-04-22 Created: 2010-04-22 Last updated: 2017-12-12
In thesis
1. Photon propagation in tissue and in biological fluids: applied for vascular imaging and haemodialysis monitoring
Open this publication in new window or tab >>Photon propagation in tissue and in biological fluids: applied for vascular imaging and haemodialysis monitoring
2003 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis focuses on the photon propagation in tissue and in biological fluids in two main areas: (1) optical vessel imaging and (2) monitoring solutes removed in haemodialysis.

The aim of the optical vessel imaging study was to design and assess a new optical scanning technique for vessel imaging using NIR radiation. The results indicated that veins could be determined at three vascular levels (superficial, intermediate and deep) down to 3 mm. Moreover, experimental results demonstrated that the vessel imaging facility depends upon source-detector separation, relative position, and vessel depth and does not depend essentially on the radiant power from the light source. After vessel imaging the technique can potentially be used to monitor several physiological parameters on a selected vascular bed (e.g. local blood flow, oxygen saturation).

The theoretical model, based on the diffusion approximation, was developed to explain theoretically the origin of experimental results. An analytical solution was obtained describing photon propagation under certain conditions during vessel identification. The modelled results confirmed previously obtained experimental results.

A new optical method for monitoring solutes in a spent dialysate using absorption of UV-radiation was developed. The obtained on-line UV-absorbance curve demonstrates the possibility to follow a single haemodialysis session continuously and to monitor deviations in the dialysator performance using UV-absorbance. The experimental results indicated that the UV-absorbance correlates well to the concentration of several solutes known to accumulate in dialysis patients indicating that the technique can be used to estimate the removal of retained substances.

Furthermore, a clinical study suggested that the delivered dialysis dose in terms of the traditional urea Kt/V could be estimated by on-line measurement of the UV-absorption in the spent dialysate. This means that the UV-method may add a new methodology for improvement of the quality and adequacy of the dialysis.

An investigation of the wavelength dependence of the UV-absorbance when monitoring different compounds in the dialysate showed that the UV-absorbance correlates well to several small molecular weight solutes ( < 200 D), around 290-310 nm. The highest contribution to the total absorbance from the observed compounds was confirmed in this wavelength region. The results indicated, that it might be possible to measure the elimination of several substances that are retained in the uraemic patients and with potential clinical significance. From thisviewpoint, the UV-absorbance monitoring technique may become a more universal method to ensure the quality and adequacy of the dialysis.

Place, publisher, year, edition, pages
Linköping: Linköpings universitet, 2003. 164 p.
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 818
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-24500 (URN)6624 (Local ID)91-737-3638-4 (ISBN)6624 (Archive number)6624 (OAI)
Public defence
2003-05-06, Berzeliussalen, Universitetssjukhuset, Linköping, 09:00 (Swedish)
Opponent
Available from: 2009-10-07 Created: 2009-10-07 Last updated: 2013-01-29

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Fridolin, IvoLindberg, Lars-Göran

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