In vitro measurements of water content and T-2 relaxation times in lung using a clinical MRI scanner

The purpose of this study was to validate water content measurements and to determine the T-2 distribution in lung on a 1.5 T clinical magnetic resona nce imaging (MRI) scanner. A single-slice 16 echo pulse sequence with an ec ho spacing of 10 msec was employed to scan 19 healthy juvenile pig lungs. T he in vitro water content of each lung was measured using MRI techniques an d compared with gravimetric measurements. The mean difference between the g ravimetric and MRI water contents was -4.1 +/- 7.6%, and an excellent linea r correlation (R-2 = 0.98) was observed between the two independent measure ments. The dependence of the geometric mean T-2 time upon lung water densit y exhibited two distinct regions (inflated and deflated) separated by a thr eshold density of about 0.4 g/mL, (C) 1999 Wiley-Liss, Inc.