Pulmonary perfusion and xenon gas exchange in rats: MR imaging with intravenous injection of hyperpolarized 129Xe.
OBJECTIVE
To develop and demonstrate a method for regional evaluation of pulmonary perfusion and gas exchange based on intravenous injection of hyperpolarized xenon 129 ((129)Xe) and subsequent magnetic resonance (MR) imaging of the gas-phase (129)Xe emerging in the alveolar airspaces.


METHODS
Five Fischer 344 rats that weighed 200-425 g were prepared for imaging according to an institutional animal care and use committee-approved protocol. Rats were ventilated, and a 3-F catheter was placed in the jugular (n = 1) or a 24-gauge catheter in the tail (n = 4) vein. Imaging and spectroscopy of gas-phase (129)Xe were performed after injecting 5 mL of half-normal saline saturated with (129)Xe hyperpolarized to 12%. Corresponding ventilation images were obtained during conventional inhalation delivery of hyperpolarized (129)Xe.


RESULTS
Injections of (129)Xe-saturated saline were well tolerated and produced a strong gas-phase (129)Xe signal in the airspaces that resulted from (129)Xe transport through the pulmonary circulation and diffusion across the blood-gas barrier. After a single injection, the emerging (129)Xe gas could be detected separately from (129)Xe remaining in the blood and was imaged with an in-plane resolution of 1 x 1 mm and a signal-to-noise ratio of 25. Images in one rat revealed a matched ventilation-perfusion deficit, while images in another rat showed that xenon gas exchange was temporarily impaired after saline overload, with recovery of function 1 hour later.


CONCLUSIONS
MR imaging of gas-phase (129)Xe emerging in the pulmonary airspaces after intravenous injection has the potential to become a sensitive and minimally invasive new tool for regional evaluation of pulmonary perfusion and gas exchange.


BACKGROUND
http://radiology.rsnajnls.org/cgi/content/full/2513081550/DC1.
Driehuys
Bastiaan
B
Center for In Vivo Microscopy, Duke University Medical Center, Box 3302, Durham, NC 27710, USA. Bastiaan.driehuys@duke.edu
Möller
Harald E
HE
Cleveland
Zackary I
ZI
Pollaro
James
J
Hedlund
Laurence W
LW
D000818:Animals; D003287:Contrast Media / Q000493:pharmacokinetics; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D010818:Practice Patterns, Physicians' / Q000639:trends; D011650:Pulmonary Alveoli / Q000502:physiology*; D011652:Pulmonary Circulation / Q000502:physiology*; D011659:Pulmonary Gas Exchange / Q000502:physiology*; D051381:Rats; D011916:Rats, Inbred F344; D012586:Science / Q000639:trends; D018581:Technology Transfer; D014979:Xenon Isotopes / Q000008:administration & dosage / Q000493:pharmacokinetics*
D003287:Contrast Media; D014979:Xenon Isotopes
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