67Ga lung scintigraphy is an established means to assess alveolar inflammation in a wide variety of diffuse lung diseases. It can be used to monitor the extent and activity of the alveolitis during the course of the disease and as a follow-up evaluation to therapy. Although the mechanism of 67Ga localization is not established firmly, the isotope appears to act as a tracer for disturbed protein and cellular fluxes within the interstitium and alveolar spaces. The radiolabeled aerosol study may also be applied to the study of these fluxes as a reflection of inflammation and injury. Although Tc-DTPA clearance studies are highly sensitive to lung injury, they may be too nonspecific to separate lung injury from other physiologic processes effectively.