Fig. 1.

A: free induction decay (FID) signal amplitude as a function of projection number at a series of respiratory rates (~110/min, 80/min, and 60/min, read from small animal monitoring system). As indicated by the black bars, peaks and troughs correspond to end-expiration and end-inspiration, respectively. B: FID phase (phase of the leading FID point) as a function of projection number. Peaks and troughs correspond to end-inspiration and end-expiration, respectively, as indicated by the black bars.