Imaging obstructed ventilation with NMR using inert fluorinated gases

Citation
Do. Kuethe et al., Imaging obstructed ventilation with NMR using inert fluorinated gases, J APP PHYSL, 88(6), 2000, pp. 2279-2286
Citations number
52
Categorie Soggetti
Physiology
Journal title
JOURNAL OF APPLIED PHYSIOLOGY
ISSN journal
87507587 → ACNP
Volume
88
Issue
6
Year of publication
2000
Pages
2279 - 2286
Database
ISI
SICI code
8750-7587(200006)88:6<2279:IOVWNU>2.0.ZU;2-H
Abstract
We partially obstructed the left bronchi of rats and imaged an inert insolu ble gas, SF6, in the lungs with NMR using a technique that clearly differen tiates obstructed and normal ventilation. When the inhaled fraction of O-2 is high, SF6 concentrates dramatically in regions of the lung with low vent ilation-to-perfusion ratios (Va/Q); therefore, these regions are brighter i n an image than where VA/Q values are normal or high. A second image, made when the inhaled fraction of O-2 is low, serves as a reference because the SF6 fraction is nearly uniform, regardless of VA/Q. The quotient of the fir st and second images displays the low-VA/Q regions and is corrected for oth er causes of brightness variation. The technique may provide sufficient qua ntification of VA/Q to be a useful research tool. The noise in the quotient image is described by the probability density function for the quotient of two normal random variables. When the signal-to-noise ratio of the denomin ator image is >10, the signal-to-noise ratio of the quotient image is simil ar to that of the parent images and decreases with pixel value.