Kiarash Emami1, Masaru Ishii2,
Stephen J. Kadlecek1, Jianliang Zhu3, Stephen Pickup1,
Yi Xin1, Puttisarn Mongkolwisetwara1, Harrilla Profka1,
Rahim R. Rizi1
1Department of Radiology, University of
Pennsylvania, Philadelphia, PA, United States; 2Department of
Otolaryngology, Johns Hopkins University, Baltimore, MD, United States; 3Department
of Surgery, University of Pennsylvania, Philadelphia, PA, United States
This
study evaluates the preliminary use of HP gas diffusion MRI to assess
alveolar recruitment dynamics in a healthy rat model. After a period of ventilation at zero
positive end-expiratory pressure (PEEP), recruitment was studied at elevated
PEEP and constant tidal volume. After
recruitment, it was found that regional ADC values initially diminished and
consistently recovered with the removal of elevated PEEP. It is therefore proposed that before
recruitment, accumulated alveolar collapse causes the over-extension of
active alveoli (high ADC); after recruitment, the fixed tidal volume is
shared by the greater number of recruited alveoli (corresponding to decreased
ADC).