This is a study on the analysis of hyperpolarized (HP) Xe-129 dynamics applied in the lung of a pathological model mouse under spontaneous respiration. A novel parameter k(1)k(2) - a product of the rate constant for Xe transfer from gas to dissolved phase (k(1)) and from dissolved to gas phase (k(2)) - was shown to be derived successfully from the analysis of the HP Xe-129 dynamic MR experiment in the mouse lung under spontaneous respiration with the aid of a selective pre-saturation technique. A comparative study using healthy mice and model mice induced with lung cancer (by injection of murine tumor B16BL6 melanoma) was performed and a significant difference was found in the k(1)k(2) values of the two groups, that is, 0.020 +/- 0.007 s(-2) (n = 4) for healthy mice and 0.032 +/- 0.04 s(-2) (n = 3) for lung cancer model mice (p = 0.04). Thus, the parameter obtained by our proposed method is considered useful for detection of lung tumors. (C) 2008 Elsevier Ireland Ltd. All rights reserved.