Figure 1. Study design for APT imaging of the mice lung using the small animal ventilator.

The animal was mechanically ventilated for constant amplitude and frequency of respiration at 32 breaths/min in which inhalation and end-expiration was 0.2 s and 1.6 s, respectively. The lung was inflated until the intrapulmonary pressure becomes 20 cm H₂O. Fast spin-echo images were obtained following a presaturation pulse (continuous-wave block pulse, B1 = 1.7 µT, duration = 4 s) in the end-expiratory phase.