Regional ventilation mapping of the rat lung using hyperpolarized ¹²⁹Xe magnetic resonance imaging.
Lung ventilation was mapped in seven healthy male Sprague-Dawley rats (433 ± 24 g) using hyperpolarized ¹²⁹Xe magnetic resonance imaging (MRI) at 3.0 T, and validated with hyperpolarized ³He MRI under similar ventilator conditions. Ventilation maps were obtained using flip angle variation for offset of RF and relaxation (FAVOR) which is a multiple breath imaging technique that extracts the fractional ventilation parameter, r, on a pixel-by-pixel basis from the dynamic signal enhancement. r is defined as the fractional refreshment of gas per breath. Under the ventilator conditions used in this work, whole-lung measurements of fractional ventilation obtained using hyperpolarized ¹²⁹Xe were not significantly different from those obtained using hyperpolarized ³He (p = 0.8125 by a Wilcoxon matched pairs test). Fractional ventilation gradients calculated in the superior/inferior (S/I) and anterior/posterior (A/P) directions obtained using hyperpolarized ¹²⁹Xe were not significantly different from those obtained using hyperpolarized ³He (p = 0.9375 and p = 0.1563, for the S/I and A/P directions, respectively). Following baseline fractional ventilation measurements, one representative rat was challenged with methacholine and fractional ventilation measurements were performed over a time course of 10 min. A reduction and subsequent recovery in whole-lung r values were detected using the FAVOR method.
Imaging Research Laboratories, Robarts Research Institute, London, Ontario, Canada.
Marcus J
MJ
Couch
Alexei
A
Ouriadov
Giles E
GE
Santyr
D000280:Administration, Inhalation; D000818:Animals; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008168:Lung / Q000378:metabolism*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D011659:Pulmonary Gas Exchange / Q000502:physiology*; D012123:Pulmonary Ventilation; D051381:Rats; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014979:Xenon Isotopes / Q000493:pharmacokinetics*
D014979:Xenon Isotopes