By taking pulmonary blood volume and thus presumably surface area into account, the radioactivity ratio represents the ratio of extravascular to intravascular 67 Ga radioactivity. The PLI represents the transport rate of 67 Ga-transferrin from the intravascular to the extravascular spaces in the lungs, and it is therefore a measure of pulmonary capillary permeability to transferrin [19, 20] . The mean PLI from the two lungs was taken. The upper limit of normal PLI is 14.1 × 10 -3 /min. Where appropriate, numbers are summarized as median (range).