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Polarized laser Doppler perfusion imaging—reduction of movement-induced artifacts
Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.ORCID iD: 0000-0002-0012-7867
2005 (English)In: Journal of Biomedical Optics, ISSN 1083-3668, Vol. 10, no 6Article in journal (Refereed) Published
Abstract [en]

Laser Doppler perfusion imaging (LDPI) enables superficial tissue perfusion assessment, but is sensitive to tissue motion not related to blood cells. The aim was to investigate if a polarization technique could reduce movement-induced artifacts. A linearly polarized laser and a cross-polarized filter, placed in front of the detectors, were used to block specular reflection. Measurements were performed with, and without, the polarization filter, at a single site during horizontal and vertical movement of skin tissue (index finger, twelve subjects, n=112) and of a flow model (n=432), with varying surface structures. Measurements were repeated during different flow conditions and at increased skin specular reflection. Statistical analysis was performed using ANOVA models. The perfusion signal was lower (p<0.001, skin and p<0.05, flow model) using the polarization filter, due to movement artifact reduction. No significant influence from surface structure was found when using the polarization filter. Movement artifacts were lower (p<0.05) in the vertical movement direction, however, depending on flow conditions for skin measurements. Increased skin specular reflection gave rise to large movement artifacts without the polarization filter. In conclusion, the polarized LDPI technique reduces movement artifacts and is particularly appropriate when assessing, e.g., ulcers and burns, where specular reflection is high.

Place, publisher, year, edition, pages
2005. Vol. 10, no 6
National Category
Medical and Health Sciences
URN: urn:nbn:se:liu:diva-30112DOI: 10.1117/1.2120467Local ID: 15582OAI: diva2:250933
Available from: 2009-10-09 Created: 2009-10-09 Last updated: 2016-05-04
In thesis
1. Movement artifact reduction in laser Doppler blood flowmetry: myocardial perfusion applications
Open this publication in new window or tab >>Movement artifact reduction in laser Doppler blood flowmetry: myocardial perfusion applications
2005 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Laser Doppler perfusion monitoring (LDPM) and imaging (LDPI) enable assessment of tissue microvascular perfusion. The techniques are based on the Doppler broadening of the optical spectrum occurring when coherent laser light is scattered by moving red blood cells (RBC). However, if tissue motion not related to moving RBCs is present, artifacts arise in the derived perfusion estimate. The aim of this thesis was to develop and evaluate methods to reduce tissue motion influence on the perfusion estimate in general and for the specific purpose of enabling myocardial perfusion monitoring in the beating heart.

An LDPM system, based on digital signal processing, was developed for myocardial perfusion assessment. To achieve an accurate estimate of the local microvascular perfusion, the varying myocardial tissue motion during the cardiac cycle is taken into account. By means of ECG-triggering, periods of minimum myocardial tissue motion can be pinpointed. The system and proposed methods were successfully evaluated both in an animal model (3 calves) and during coronary artery bypass grafting (CABG) on 13 humans. Animal studies showed the importance of processing during minimum tissue motion, at late diastole and/or late systole, to reduce movement artifacts. The human evaluation confirmed earlier animal findings and revealed low flow situations in the intraoperative phase. Influence of mechanical ventilation on the myocardial blood flow was found. The results justify investigation postoperative of CABG, where myocardial perfusion monitoring may give a rapid response to potential ischemia.

The influence of tissue motion on LDPI was studied in model measurements and on the skin. A relatively large tissue velocity, compared to microvascular flow velocities, was needed to significantly influence the perfusion signal. Movement artifact magnitude depended on the movement direction and the surface structure. An LDPI system utilizing a polarization technique that blocks specularly reflected light is proposed. The method was evaluated in a flow model and on the skin of 12 subjects and was found to significantly reduce influence from tissue motion. Finally, a theoretical explanation of the origin of LDPI movement artifacts is proposed. Reduction of movement artifacts makes measurements more reliable and increases the potential of LDPI as a clinical tool.

Place, publisher, year, edition, pages
Linköping: Linköpings universitet, 2005. 84 p.
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 935
National Category
Medical and Health Sciences
urn:nbn:se:liu:diva-28804 (URN)13992 (Local ID)91-85297-73-9 (ISBN)13992 (Archive number)13992 (OAI)
Public defence
2005-04-29, Linden, ingång 65, Campus US, Linköpings universitet, Linköping, 09:15 (English)
Available from: 2009-10-09 Created: 2009-10-09 Last updated: 2012-11-30Bibliographically approved

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Karlsson, Daniel M GWårdell, Karin
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