&lt;title&gt;Single fiber, laser Doppler flowmetry (LDF) for detecting muscle microcirculation in the low leg and its technique improvement&lt;/title&gt;

Cai, Hongming; Öberg, Peter; Rohman, H.; Larsson, Sven‐Erik

doi:10.1117/12.201236

Cited by 2 publications

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“…This technique was further developed by us and applied for research purposes and clinical use. [5][6][7][8][9][10] A disadvantage of the single fiber technique is that the monitored tissue volume is relatively small. 11 This, in combination with the heterogeneous perfusion of the skeletal muscle, may lead to unreliability in the obtained muscle perfusion data.…”

Section: Introductionmentioning

confidence: 99%

Single Fiber Laser-Doppler Flowmetry—Dependence on Wavelength and Tip Optics

1998

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Single fiber, laser-Doppler flowmetry can be used for blood flow measurement in deeply located tissue structures by the insertion of optical fibers into the tissue. The geometry of the monitored volume has been estimated at two different wavelengths and when using two types of fiber tips, one of which has been modified with a lens formed at the fiber end surface. Physical models as well as intramuscular measurements have been used in the experiments. The scattering image was studied in latex solutions of three different scatterer concentrations. The wavelengths 632.8 and 750 nm were used. At higher concentrations of scatterers, the near infrared (NIR) wavelength gave a larger scattering area. At the lower concentration, the difference between the areas was smaller or nonexistent. The NIR wavelength also showed an increased monitoring depth than that of the He-Ne laser in an experimental model study. The properties of the tip optics were evaluated in a flow-through model where the distance between the fiber tips and the flow channel was varied. The flat tip fiber has a sensitivity maximum close to its end surface, whereas the modified fiber ("pear" tip) showed a sensitivity maximum 1.5 mm from the end surface. This property may decrease the influence caused by the insertion trauma in intramuscular measurements. © 1998 Society of Photo-Optical Instrumentation Engineers.

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Section: Introductionmentioning

confidence: 99%

Single Fiber Laser-Doppler Flowmetry—Dependence on Wavelength and Tip Optics

1998

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Laser Doppler flowmetry: characteristics of a modified single-fibre technique

Cai

Rohman

Larsson

et al. 1996

Med. Biol. Eng. Comput.

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The single-fibre percutaneous laser Doppler technique has been used in previous studies of intramuscular blood flow. This method facilitates studies of blood flow in deep tissue volumes and minimises the tissue trauma. The technique has been further developed with the aim of improving the signal quality. This has been accomplished by modifying the geometry of the fibre tip. By melting the fibre core material, lenses of different shapes are formed. Flat, spherical and 'pear'-type tips have been manufactured and are evaluated theoretically and experimentally. The paraxial theory cannot accurately predict the position of zones of highest irradiance. Therefore, a ray-tracing program has been developed in the C language, by means of which some of the optical properties of the modified fibre tips can be simulated. Iso-irradiance graphs and beam profiles are calculated for the three different fibre tips. Measured and calculated irradiance curves are used for evaluation of the properties of the ray-tracing model. The three types of fibre tips are also evaluated and compared in flow models. The sphere and pear-type probes show a higher flow sensitivity than the flat-end type. These improvements in flow sensitivity are interpreted as being related to the larger, strongly irradiated tissue volumes in front of the fibres. Intramuscular measurements with the pear-type probe show high sensitivities to induced blood flow changes.

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<title>Single fiber, laser Doppler flowmetry (LDF) for detecting muscle microcirculation in the low leg and its technique improvement</title>

Cited by 2 publications

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Single Fiber Laser-Doppler Flowmetry—Dependence on Wavelength and Tip Optics

Single Fiber Laser-Doppler Flowmetry—Dependence on Wavelength and Tip Optics

Laser Doppler flowmetry: characteristics of a modified single-fibre technique

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