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

Direct link
Towards a velocity-resolved microvascular blood flow measure by decomposition of the laser Doppler spectrum
Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.ORCID iD: 0000-0001-6385-6760
Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
2006 (English)In: Journal of Biomedical Optics, ISSN 1083-3668, Vol. 11, no 1Article in journal (Refereed) Published
Abstract [en]

The tissue microcirculation, as measured by laser Doppler flowmetry (LDF), comprises both capillary, arterial and venous blood flow. With the classical LDF approach, it has been impossible to differentiate between different vascular compartments. We suggest an alternative LDF algorithm that estimates at least three concentration measures of flowing red blood cells (RBCs), each associated with a predefined, physiologically relevant, absolute velocity in mm/s. As the RBC flow velocity depends on the dimension of the blood vessel, this approach might enable a microcirculatory flow differentiation. The LDF concentration estimates are derived by fitting predefined Monte Carlo simulated, single velocity, spectra to a measured, multiple velocity LDF spectrum. Validation measurements, using both single and double-tube flow phantoms perfused with a microsphere solution, showed that it is possible to estimate velocity and concentration changes, and to differentiate between flows with different velocities. The presented theory was also applied to RBC flow measurements. A Gegenbauer kernel phase function (αgk = 1:05; ggk = 0:93), with an anisotropy factor of 0.987 at 786 nm, was found suitable for modelling Doppler scattering by red blood cells diluted in physiological saline. The method was developed for low concentrations of RBCs, but can in theory be extended to cover multiple Doppler scattering.

Place, publisher, year, edition, pages
Institutionen för medicinsk teknik , 2006. Vol. 11, no 1
Keyword [en]
Doppler effect, biomedical optics, optical properties, anisotropy, laser Doppler
National Category
Engineering and Technology
URN: urn:nbn:se:liu:diva-11648DOI: 10.1117/1.2166378OAI: diva2:18063
Copyright 2006 Society of Photo-Optical Instrumentation Engineers. This paper was published in the Journal of Biomedical Optics, (11), 14024 and is made available as an electronic reprint with permission of SPIE. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited. Marcus Larsson and Tomas Strömberg, Towards a velocity resolved microvascular blood flow measure by decomposition of the laser Doppler spectrum, 2006, Journal of Biomdeical Optics, (11), 14024. from: 2008-04-23 Created: 2008-04-23 Last updated: 2016-08-31
In thesis
1. Influence of optical properties on Laser Doppler Flowmetry
Open this publication in new window or tab >>Influence of optical properties on Laser Doppler Flowmetry
2004 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Laser Doppler flowmetry (LDF) is based on the principle that a Doppler shift occurs when coherent light is scattered by a moving object, i.e. red blood cell (RBC). The magnitude of these frequency shifts affects the optical beating that occurs w hen shifted and non-shifted light is mixed. Based on the optical beating, an LDF perfusion measure is calculated. However, the measure is not only sensitive to the RBC velocity and concentration, but also to the photon path Jength in tissue and the scattering characteristics of the RBC. The Jatter two are both govemed by the optical properties (OP), attributes that differ both within and between individuals.

The aim of this thesis was to evaluate how the RBC and tissue OP affect the LDF perfusion measure, and to propose methods that partly correct for these errors. Phantom measurements and Monte Carlo simulations showed that the LDF perfusion was significantly affected by variations in OP relevant to skin, especially when comparing individual readings. Simulations revealed that the variations in OP affected the LDF perfusion and the photon path length in a similar manner. This suggests that a path length normalised measure would decrease the OP induced variations, possibly enabling accurate intra and inter-individual comparisons of LDF perfusion measures in different organs.

A path length estimation technique, based on spatially diffuse reflectance, is proposed and evaluated. Monte Carlo simulations showed that the algorithm predicted the photon path length with an rms error of less than 5%. In vivo measurement (11 subjects) displayed a longer estimated path length (~35%) for the fingertip compared to the forearm. Comparing individual measurements from similar locations, variations up to 40% (max/min) were found. These findings clearly indicate the need for a path length normalization when comparing LDF readings.

The LDF Doppler spectrum is govemed by the RBC velocity distribution and its phase function. In this thesis, an approach is presented where a measured LDF Doppler spectrum is decomposed using a number of theoretical, single-velocity spectra. As a result, a velocity-resolved perfusion measure is achieved. As the blood flow velocity depends on the dimension of the blood vessel, this approach has the potential to differentiate between arteriole/ venule and capillary activity. In addition, the path length estimation technique and the RBC scattering theory, presented in this thesis, provides a promising step towards an absolute perfusion measure.

Place, publisher, year, edition, pages
Linköping: Linköpings universitet, 2004. 64 p.
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 914
National Category
Medical and Health Sciences
urn:nbn:se:liu:diva-28932 (URN)14139 (Local ID)91-85297-04-6 (ISBN)14139 (Archive number)14139 (OAI)
Public defence
2004-12-17, Sal Eken, Universitetssjukhuset, Linköping, 09:15 (Swedish)
Available from: 2009-10-09 Created: 2009-10-09 Last updated: 2016-08-31

Open Access in DiVA

fulltext(233 kB)538 downloads
File information
File name FULLTEXT01.pdfFile size 233 kBChecksum SHA-1
Type fulltextMimetype application/pdf

Other links

Publisher's full text

Search in DiVA

By author/editor
Larsson, MarcusStrömberg, Tomas
By organisation
Biomedical InstrumentationThe Institute of Technology
In the same journal
Journal of Biomedical Optics
Engineering and Technology

Search outside of DiVA

GoogleGoogle Scholar
Total: 538 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 930 hits
ReferencesLink to record
Permanent link

Direct link