Fig. 2

a Feet head motion recorded by the iNAV. b Thoracic motion recorded with the respiratory belt. c Overlapping signal from the iNAV (a) and the respiratory belt (b). The solid vertical lines represent the R-peak in the ECG signal. The dots on curve in sub-plot a represent the time points at which the iNAV was acquired in the R–R wave. The crosses on curve in sub-plot b represent the corresponding time points signal from the respiratory belt. The shaded horizontal regions in panel a and b represent the 4 bins. All PET data acquired in an R-R interval is allocated to one of the 4 bins. The bin to which the data is allocated is based on the displacement of the heart as determined by the iNAV. For example, in panel a, the data in the first panel is allocated to bin 2 as the iNAV acquired for the R–R interval falls within the bin 2 thresholds. The four colors represent the 4 bins. Red represents bin 1, cyan bin 2, black bin 3 and green bin 4