Fig. 4. PACTER of mouse hemodynamics in vivo.

a, Schematic of the mouse imaging experiment. b,c, 3D PACTER images of the abdominal vasculature of mouse 1 (b) and mouse 2 (c). Norm., normalized. d,e, Cross-sectional 2D images corresponding to the yellow rectangle in b (d) and the magenta rectangle in c (e) at four different time instances from the 4D PACTER datasets. t₀ = 0.28 s, t₁ = 0.26 s. White solid curves represent the Gaussian fits of the vessels’ profile denoted by the yellow (d) and magenta (e) dashed lines. Differences from the first image are highlighted. f,g, PA amplitudes along the yellow dashed line (1D images) in d (f) and the magenta dashed line in e (g) versus time, where the time instances in d and e are labeled with vertical gray lines. h,i, Center positions (blue solid curves) and widths (orange dash-dotted curves) of the vessels versus time, based on the fits in d (h) and e (i). The shaded areas denote the standard deviations (n = 5). j,k, Fourier transforms of the center positions and widths of the vessels in h (j) and i (k), showing the respiratory frequency from the vessel center positions only (j) or both the vessel center positions and widths (k). Scale bars, 1 mm.