| 1. |
- Golster, Helena, et al.
(författare)
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Red Blood Cell Velocity and Volumetric Flow Assessment by Enhanced High-Resolution Laser Doppler Imaging in Separate Vessels of the Hamster Cheek Pouch Microcirculation
- 1999
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Ingår i: Microvascular Research. - : Elsevier BV. - 0026-2862 .- 1095-9319. ; 58:1, s. 62-73
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Tidskriftsartikel (refereegranskat)abstract
- An enhanced high-resolution laser Doppler imager (EHR-LDI), configured to fit the demands of a measurement area containing separate microvessels, was evaluated for perfusion measurements in hamster cheek pouch preparations during ischemia, reperfusion, and pharmacologically induced vasodilation and vasoconstriction. Measurements in separate microvessels where the laser beam was smaller than the vessel diameter were referred to as red blood cell (RBC) velocity estimates, as previously validated in vitro, whereas a relative flow index, RFI (mean RBC velocity/tissue area), was introduced as a volumetric flow measure. Microvessel diameter and RBC velocity changes during ischemia, reperfusion, as well as during vasoconstriction and vasodilation correlated to the data obtained from the microscope. Correspondingly, during the described provocations anticipated volumetric flow changes were registered as changes in the RFI. When data on intravessel RBC velocity profiles are presented they reflect a parabolic flow profile usually seen in this size microvessel. The EHR-LDI appears a promising tool for investigation of the microvasculature, as it almost simultaneously provides information on relative changes of both in vivo RBC velocity and volumetric flow (RFI), although the latter estimate needs to be further refined.
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| 2. |
- Lindén, Maria, 1965-, et al.
(författare)
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Evaluation of Enhanced High-Resolution Laser Doppler Imaging in an in Vitro Tube Model with the Aim of Assessing Blood Flow in Separate Microvessels
- 1998
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Ingår i: Microvascular Research. - : Elsevier BV. - 0026-2862 .- 1095-9319. ; 56:3, s. 261-270
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Tidskriftsartikel (refereegranskat)abstract
- An enhanced high-resolution laser Doppler imaging (EHR-LDI) technique intended for visualization of separate microvessels was evaluated by use ofin vitroflow models. In EHR-LDI, a laser beam focused to a half-power diameter less than 40 μm successively scans the tissue under study in steps of 25 μm. Spatial blood flow variations within microvascular structures of 1.5 × 1.5 mm are rendered by 64 × 64 measurement sites. Individual microvessel diameters could be estimated and an average difference of 11 μm compared to microscopic measurements was obtained. For the flow algorithm used, the LDI output signal was found to scale linearly with average velocity (0–3.5 mm/s) when a plastic tube of inner diameter 175 μm was perfused with human blood (correlation coefficient 0.99). The LDI output signal was further found insensitive to hematocrit variations in the range 16–44%. Due to the limited laser light penetration in blood, a reduction in the LDI output signal was observed as the inner tube diameters were successively changed from 280 to 1400 μm.
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