Journal of Applied Physiology, Vol 66, Issue 3 1197-1208, Copyright © 1989 by American Physiological Society
Assessment of temporal changes in pulmonary edema with NMR imaging
D. M. Phillips, P. S. Allen and S. F. Man
Division of Pulmonary Medicine, University of Alberta, Edmonton, Canada.
Nuclear magnetic resonance imaging (NMRI) parameters [longitudinal
relaxation time (T1), transverse relaxation time (T2), and signal
intensity] acquired at a magnetic field of 2.35 T were validated with a
study of nine different phantom gel solutions. This technique was then
applied to study 13 anesthetized supine cats, among which 10 had lung edema
induced by oleic acid (0.075 ml/kg); the result was compared with
postmortem analyses of lung water. Three animals (series A) were imaged
until the edema was first visualized in NMRI, usually 15-20 min after oleic
acid infusion. Another seven animals (series B) were imaged over 4-5 h. As
lung water increased, so did the signal intensity. When edema first
appeared, T1, T2, and the volume of the edematous region within the slice
in the upper lobes showed no gravity-dependent differences; this was
confirmed by postmortem measurements (series A) of lung water. With time,
gravity-dependent regions displayed greater volumes of edematous regions
and greater T1 values (P less than 0.01), suggesting a continued
accumulation of lung water. In comparison, nondependent regions displayed
constant volumes of edematous region and lesser T1 values (P less than
0.01), suggesting an increased protein concentration but no change in lung
water. This study suggests the potential applicability of NMRI parameters
in the assessment of pulmonary edema.
