Determination of regional ventilation and perfusion in the lung using xenon and computed tomography.
Kreck, Thomas C., Melissa A. Krueger, William A. Altemeier, Scott E. Sinclair, H. Thomas Robertson, Erin D. Shade, Jacob Hildebrandt, Wayne J. E. Lamm, David A. Frazer, Nayak L. Polissar, and Michael P. Hlastala.
Departments of 1Medicine and 2Physiology and Biophysics, University of Washington, Seattle 98195-6522; and 3Mountain-Whisper-Light Statistical Consulting, Seattle, Washington 98112
APStracts 8:0288A, 2001.
We propose a model to measure both regional ventilation ("odot"V) and perfusion ("odot"Q) in which the regional radiodensity (RD) in the lung during xenon (Xe) washin is a function of regional "odot"V (increasing RD) and "odot"Q (decreasing RD). We studied five anesthetized, paralyzed, mechanically ventilated, supine sheep. Four 2.5-mm-thick computed tomography (CT) images were simultaneously acquired immediately cephalad to the diaphragm at end inspiration for each breath during 3 min of Xe breathing. Observed changes in RD during Xe washin were used to determine regional "odot"V and"odot"Q. For 16 mm3, "odot"Q displayed more variance than "odot"V: the coefficient of variance of "odot"Q (CV"odot"Q) = 1.58 ± 0.23, the CV of "odot"V (CV"odot"V) = 0.46 ± 0.07, and the ratio of CV"odot"Q to CV"odot"V = 3.5 ± 1.1. CV"odot"Q (1.21 ± 0.37) and the ratio of CV"odot"Q to CV"odot"V (2.4 ± 1.2) were smaller at 1,000-mm3 scale, but CV"odot"V (0.53 ± 0.09) was not. "odot"V/"odot"Q distributions also displayed scale dependence: log SD of "odot"V and log SD of "odot"Q were 0.79 ± 0.05 and 0.85 ± 0.10 for 16-mm3 and 0.69 ± 0.20 and 0.67 ± 0.10 for 1,000-mm3 regions of lung, respectively. "odot"V and "odot"Q measurements made with CT and Xe also demonstrate vertically oriented and isogravitational heterogeneity, which are described using other methodologies. Sequential images acquired by CT during Xe breathing can be used to determine both regional "odot"V and "odot"Q noninvasively with high spatial resolution.
Received 19 September 2000; accepted in final form 25 April 2001
APS Manuscript Number A909-0.
Article publication pending J Appl Physiol
ISSN 1080-4757 Copyright 2001 The American Physiological Society.
Published in APStracts on 18 June 2001