Fig. 8

Heart rate detection and acquisition of gating signal in embryonic animals. a Four-frame time series showing color changes associated with the heartbeat in color-magnified video of embryonic chicken at day 2.4 in a candled, non-windowed egg (Additional file 10). b Pixel-wise standard deviation (STD) of magnified video highlighting embryonic heart. c, d Image probes (c) and vertical scan line over time (d) showing temporal variation at embryonic heart intersection. e, f Embryonic heart and background signal (yellow and gray rings in c) development over time (e) (combined channels), and Fourier-transformed signal in the frequency domain (f). g Line chart (mean ± 95% confidence interval) of heartbeat signal to noise ratio (SNR) during 9 days in intact and windowed eggs measured at the embryonic heart or vitelline vessels. h Enlargement of box in g (only vessel signals). Color coded asterisks (*) in g, h indicate statistically significant differences from SNR = 1. i Line chart comparing heart rate acquired with video magnification to reference values (Lindsey et al., 2014). Asterisks indicate statistically significant differences from reference values. j Embryonic chicken at day 7. k–n Three-dimensional rendering of embryonic chicken at day 7 from micro-CT (μCT) imaging gated by magnified optical signal. Volumetric reconstruction of the heart and vascular system of the embryo in a resealed egg (k–m) and segmentation of the heart chambers in two phases (n). o Single frame from color-magnified video of pregnant mouse abdomen (E17.5) (Additional file 12). p Vertical scan line from magnified video over time. q Magnification of box in p, showing color fluctuations associated with embryonic heartbeat. r–t Ultrasound (r, pulsed wave Doppler; t, brightness mode) and μCT (s) validation of heart rate and position of embryo. u, v Embryonic heart and background signal (yellow and gray rings in o) development over time (u) (combined channels), and Fourier-transformed signal in the frequency domain (v)