Fig. 6. Magnetic resonance volumetric imaging of collagenase-induced hemorrhage. A , Representative axial T2-weighted brain images were obtained at 2 h after collagenase injection but before 20 h of either 30% Xe or 0% Xe exposure and repeated at 24 h postcollagenase injection. In both groups of mice, evolution of parenchymal hemorrhage was observed over the 22-h interval. Arrows  provide examples of lesion borders used to define hemorrhage volume. B , Hemorrhage volumes for individual mice (open  and closed circles ) were not different between groups at either the 2-h (P = 0.42) or 24-h (P = 0.37) measurement. Horizontal bars  indicate group mean values. Mean hematoma growth over 22 h also was not different between the 0 and 30% Xe groups (P = 0.98). Xe = Xenon.