Fig. 1.

A: schematic diagram of the ventilation protocol for end-inspiratory apparent diffusion coefficient (ADC) imaging in rat lungs with hyperpolarized ³He MRI. b values, diffusion gradient factors. B: schematic diagram of the two positive end-expiratory pressure (PEEP) recruitment maneuvers. The thick line segments represent ADC acquisitions. C: overall experimental protocol comprised of two recruitment maneuvers sandwiched between two pairs of ADC measurements and separated by a wait time period, as shown in Table 1.