Pulmonary blood flow (PBF) ratio of right/left side for the control group and injury/reference side for the entire lung (ROIlung side) and for a spherical region of interest of 0.24 cm³ (ROI_specific). Higher mean concentrations of Ga-68 microspheres in the injured region yield a PBF quotient >1 in ROIlung side or ROI_specific. *P < 0.0001 compared with the control group. ROI = region of interest.