Determination of venous blood flow velocity using digital videomicroscopy (A short methodical communication).
OBJECTIVE
There is a limited number of methods to measure blood flow velocity in small veins. A cheap and simple new videomicroscopic method developed in our laboratories is described in the paper.


METHODS
A stretch of the saphenous vein of the rat was exposed by careful micropreparation on the thigh of anesthetized animals. Bolus amount (approx. 5 μl) of saline was infused into a small side branch through a microcannula to dilute flowing blood. Videomicroscopic picture of the vein was then taken of the exposed upstream stretch of the vein. Serial pictures were digitized and analyzed using macro functions of the Image J software. Sensitive areas of serial pictures were selected and fitted. Consecutive pictures were subtracted from each other to better characterize their alteration in-between frames. Greyscale intensity values measured at different points of the inner diameter were averaged for each point of the vessel axis. Cross-correlations along the axis were then computed for consecutive frames with delays of 40, 80, 120 and 160 msec. Pixel offsets producing cross-correlation maxima were determined and used to compute mean flow velocity.


RESULTS
Combination of digital subtraction and cross-correlation computations yielded easily identifiable maximums. Mean flow velocities could be determined with limited uncertainty.


CONCLUSIONS
The described technique gives a cheap, simple and reproducible mean to determine mean blood flow velocities in small veins in anesthetized animals, where other current techniques (ultrasonography, laser-Doppler, fluorescently labelled red cell movement) are either expensive or can be applied with difficulty only.
Budapest University of Technology and Economics Department of Hydrodynamic Systems Műegyetem rakpart 3, Build. D, 3rd floor H-1111 Budapest Hungary.
Gergely
G
Bárdossy
C
C
Lantos
G
G
Halász
E
E
Monos
G L
GL
Nádasy
D000818:Animals; D001783:Blood Flow Velocity; D007090:Image Interpretation, Computer-Assisted; D007262:Infusions, Intravenous; D018715:Microscopy, Video; D011237:Predictive Value of Tests; D051381:Rats; D012039:Regional Blood Flow; D015203:Reproducibility of Results; D012501:Saphenous Vein / Q000502:physiology*; D012965:Sodium Chloride / Q000008:administration & dosage
D012965:Sodium Chloride