Regional extravascular density and fractional blood volume of the lung in interstitial disease.

Regional lung density (g lung/ml thoracic volume) and fractional pulmonary blood volume (ml blood/ml thoracic volume) have been measured by positron tomography in 10 patients with interstitial disease. From the measurements regional extravascular lung density (g tissue and interstitial water/ml thoracic volume) was derived, providing a non-invasive measurement of the interstitial reaction. Extravascular lung density was increased and large regional variations were observed. Fractional blood volume was reduced in patients with pulmonary fibrosis. In two patients with sarcoidosis, a reduction in extravascular lung density occurred after treatment with oral prednisone. Abnormalities in extravascular lung density and fractional blood volume correlated with abnormalities shown by tests of overall pulmonary function.