title: Krypton for computed tomography lung ventilation imaging: preliminary animal data.
abstract: OBJECTIVE
  The objective of this study was to assess the feasibility and safety of krypton ventilation imaging with intraindividual comparison to xenon ventilation computed tomography (CT).
  
  
  METHODS
  In a first step, attenuation of different concentrations of xenon and krypton was analyzed in a phantom setting. Thereafter, 7 male New Zealand white rabbits (4.4-6.0 kg) were included in an animal study. After orotracheal intubation, an unenhanced CT scan was obtained in end-inspiratory breath-hold. Thereafter, xenon- (30%) and krypton-enhanced (70%) ventilation CT was performed in random order. After a 2-minute wash-in of gas A, CT imaging was performed. After a 45-minute wash-out period and another 2-minute wash-in of gas B, another CT scan was performed using the same scan protocol. Heart rate and oxygen saturation were measured. Unenhanced and krypton or xenon data were registered and subtracted using a nonrigid image registration tool. Enhancement was quantified and statistically analyzed.
  
  
  RESULTS
  One animal had to be excluded from data analysis owing to problems during intubation. The CT scans in the remaining 6 animals were completed without complications. There were no relevant differences in oxygen saturation or heart rate between the scans. Xenon resulted in a mean increase of enhancement of 35.3 ± 5.5 HU, whereas krypton achieved a mean increase of 21.9 ± 1.8 HU in enhancement (P = 0.0055).
  
  
  CONCLUSIONS
  The use of krypton for lung ventilation imaging appears to be feasible and safe. Despite the use of a markedly higher concentration of krypton, enhancement is significantly worse when compared with xenon CT ventilation imaging, but sufficiently high for CT ventilation imaging studies.
authors.affiliation: From the *Department of Diagnostic and Interventional Radiology, Philipps-University, Marburg, and †MR & CT Contrast Media Research, Bayer Healthcare, Berlin, Germany.
authors.forename: Andreas H
authors.initials: AH
authors.lastname: Mahnken
authors.forename: Gregor
authors.initials: G
authors.lastname: Jost
authors.forename: Hubertus
authors.initials: H
authors.lastname: Pietsch
mesh_terms: D000280:Administration, Inhalation; D000818:Animals; D003287:Contrast Media / Q000008:administration & dosage; D005240:Feasibility Studies; D006801:Humans; D007726:Krypton / Q000008:administration & dosage*; D008297:Male; D010865:Pilot Projects; D012123:Pulmonary Ventilation; D011817:Rabbits; D011856:Radiographic Image Enhancement / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014978:Xenon / Q000008:administration & dosage*
chemical_list: D003287:Contrast Media; D014978:Xenon; D007726:Krypton