Positron emission tomography measurements of pulmonary vascular permeability with Ga-68 transferrin or C-11 methylalbumin

OBJECTIVE: To compare estimates of pulmonary endothelial barrier integrity obtained using two different tracer proteins. DESIGN: Measure the pulmonary transcapillary escape rate with gallium (Ga)-68 labeled transferrin (PTCER(tf)) and positron emission tomography (PET) imaging and compare the results to similar measurements obtained with C-11 labeled methylalbumin (PTCER(alb)). SETTING: Laboratory investigation. SUBJECTS: Mongrel dogs. INTERVENTIONS: No intervention in one group of dogs (n = 3); oleic-acid induced lung injury in another set (n = 4). MEASUREMENTS AND MAIN RESULTS: Although PTCER(tf) was consistently higher than PTCER(alb) (mean difference: 50 x 10(-4)/min), the overall correlation between the two methods, after normalizing for differences in regression slope and intercept among the individual dogs, was excellent (r2 = .67). CONCLUSION: The data support the continued use of PET and Ga-68 transferrin as an appropriate means of evaluating and quantifying lung injury.