\bibitem{Bankier04}    A.A.~Bankier, C.R.~O'Donnell, V.M.~Mai, P.~Storey, V.~De Maertelaer, R.R.~Edelman, Q.~Chen,
                       {\it Impact of Lung Volume on MR Signal Intensity Changes of the Lung Parenchyma},
                       JMR Imag. {\bf 20}, 961-966, 2004.