T1 mapping of the entire lung parenchyma: Influence of the respiratory phase in healthy individuals

Abstract

Purpose To determine the effect of respiratory phase on the T1 values of the entire lung. Materials and Methods We calculated T1 relaxation time on a pixel‐by‐pixel analysis of a series of Snapshot FLASH tomograms acquired after a single inversion pulse. Two sets of coronal T1 maps were acquired, one in full suspended inspiration and one in suspended expiration. Results The average of the mean T1 values over the entire lung in inspiration was 1199 ± 117 msec, the average of the mean T1 values in expiration was 1333 ± 167 msec. This difference was statistically significant, at P = 0.005. In inspiration the average coefficient of variation was 182 ± 56 msec, in expiration it was 153 ± 41 msec. This difference was not statistically significant. Conclusion T1 measurements of the entire lung are feasible. Our findings underline the need for a close monitoring of the inspirational status during MR examinations of the thorax, notably when T1 measurements of the lung are performed. J. Magn. Reson. Imaging 2005;21:759–764.