Masaru Ishii1,
  Hooman Hamedani2, Stephen J. Kadlececk2, Kiarash Emami2,
  Yi Xin2, Milton Rossman3, Rahim Rizi2
 1Otolarynology,
  Johns Hopkins Medical Center, Baltimore, MD, United States; 2Department
  of Radiology, University of Pennsylvania, Philadelphia, PA, United States; 3Pulmonary,
  allergy and Critical Care Division, University of Pennsylvania, Philadelphia,
  PA, United States
In this work we present the first large-scale short-term lung gas exchange imaging reproducibility study using Hyperpolarized 3He. We estimated the short-time reproducibility of regional pAO2 measurements in asymptomatic smokers and non-smokers and found that the repeatability is similar in two groups and is a strong function of measurement noise. We also showed that asymptomatic smokers, while appearing normal from the physical exam and PFT standpoint, show demonstrable difference in temporal and spatial imaging characteristics.