A. Lentner et al., SPATIAL SHIFT ALIGNMENT (SSA) - A NEW TEC HNIQUE FOR MEASURING CAPILLARY BLOOD VELOCITY IN CAPILLAROSCOPY, Biomedizinische Technik, 39(7-8), 1994, pp. 170-175
A new technique (spatial shift alignment [SSA]) for measuring capillar
y blood velocity in human capillaries in the skin is described. A capi
llaroscopic image is digitized by means of a frame grabber. Within the
lumen of a suitable capillary limb a region of interest known as a sl
ot is placed. At a frame frequency of 25 per second, this slot is copi
ed in a free part of the frame grabber store along a horizontal axis.
A static space-time image with light diagonal bands representing the p
lasma gaps in their passage through the capillary limb is obtained. By
determining the gradient of the diagonal bands, a measure of the capi
llary blood velocity is obtained. The SSA system was validated by mean
s of a simulated model using known fixed velocities between 0 and 1.0
mm/sec (r = 0.979, n = 24). The procedure can be employed with any ima
ge processing systems, and enables continuous monitoring of the veloci
ty measurements. Since it is time-saving and just as accurate as the f
rame-to-frame method, SSA could be widely applied to the measurement o
f blood cell velocity in capillaroscopy.