Video 3. Blood velocity profile across 20 cardiac phases imaged noninvasively in a 25.3 µm arteriole.
Top: Space-time image (10 s) of the 25.3 µm arteriole shown in Figure 4. Image is overlaid with measured absolute single-cell velocity, as described in the paper. Scale bars: 300 ms (horizontal), 60 µm (vertical). Middle: Zoom-in of purple box, showing a single representative cardiac pulse in the space time image. Scale bars: 10 ms (horizontal), 25 µm (vertical). Bottom-left: A ~ 12 ms window of the space-time image (red box) is shown in both raw form (showing single blood cell streaks) and in velocity overlaid form. Scale bars: 3 ms (horizontal), 10 µm (vertical). Bottom right: The first plot shows an average cardiac cycle computed from n = 35 cycles, same as Figure 4G. The second plot shows the velocity (spatial) profile as a function of cardiac phase. Figure 4H had only shown the diastolic and systolic phases. The bluntness and height of the profile can be observed to change with cardiac phase. Bluntness index (B) and relative height of profile edges (β) were quantified using Equation 7 in the paper. Bsystolic = 1.67, Bdiastolic = 1.39, βsystolic = 0.34, βdiastolic = 0.46. Shaded regions in both plots show mean ± SD.