99mTc-DTPA clearance measured by a dual head gamma camera in healthy subjects and patients with sarcoidosis. Studies of reproducibility and relation to bronchoalveolar lavage findings.

99mTc-DTPA clearance was studied in ten healthy non smokers, five asymptomatic smokers and nine non smoking patients with sarcoidosis in the supine position with a dual head gamma camera allowing simultaneous information of regional clearance rates in frontal and dorsal projections. In the patients with sarcoidosis, a bronchoalveolar lavage was performed prior to the clearance study. DTPA clearance rate was measured during 60-90 min and data were corrected for recirculating radioactivity. The coefficients of variation for measurements on 2 consecutive days in the 10 healthy non smokers were 9%-11% for the right and left lung, anterior and posterior projections. The T1/2 calculated from total lung projections were 90-92 min for the anterior view and 84-85 min for the posterior view. Regional measurements did not add further information. No apico-basal difference was found but there was a significant fronto-dorsal gradient in 99mTc-DTPA clearance in the supine position. Smokers had significantly (P less than 0.01) faster clearance rates (T1/2 28 +/- 10 min) than healthy controls. In the sarcoidosis group clearance rates were increased in four patients and no relationships were found between DTPA clearance rates and inflammatory markers (lymphocytes, albumin, ACE) in the bronchoalveolar lavage fluid.