Study objective: Pulmonary vascular leakiness of 67Ga-circulating transferrin in interstitial pneumonitis (IP) was estimated by our previously described method, and its ability to evaluate disease activity was compared with conventional 67Ga scintigraphy. Design: Using 30-min dynamic scanning data after IV injection of 67Ga citrate, the exponential equilibration coefficient of 67Ga between the intravascular and pulmonary interstitial compartments was calculated and defined as the leak index (LI). Pulmonary 67Ga uptake was assessed by gallium index, determined by conventional static images taken 48 h after 67Ga citrate injection. Setting: Hospitalized patients. Participants: The study population consisted of 17 control patients and 20 patients with IP. Results: The mean LI in patients with IP was significantly higher than in the control group (p < 0.0001), whereas no significant increase in gallium index was noted between the IP group and the control group. No significant correlation was found between gallium index and LI among all study participants. Mean LI in patients with active IP was significantly higher than in patients with stable IP (p 0.0024). Conclusions: An increase in pulmonary vascular leakiness was found in patients with IP. LI may be useful to assess the disease activity.
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