Scintiscanning with aerosols of 99Tcm DTPA in the diagnostic strategy for pneumocystosis in aids patients

Pulmonary clearance of an aerosol of 99Tcm DTPA was measured in 21 non-smoking AIDS and pneumocystosis patients. The results were compared with those of pulmonary scintiscanning with gallium. All the patients exhibited increased clearance, evidence of a considerable alteration in alveolar permeability. This increase was also observed in patients with normal chest X-rays and normal blood gases. The average clearance in these patients was 6 ± 2% min-1 as compared with a normal 1.1 ± 0.3% min-1. Conversely, only four out of eight patients with normal chest X-rays had abnormal gallium scans. Clearance returned to normal after recovery. Measurement of DTPA clearance appears to be a very sensitive indicator for the detection and follow-up of pneumocystosis. However, it is not very specific since it can be increased by tobacco poisoning, drug abuse and the presence of lymphocytic alveolitis. An examination with normal findings can therefore exclude the possibility of opportunistic pneumopathy and make bronchial lavage unnecessary. An examination with abnormal findings should show whether lavage is indicated, even if the chest X-rays, blood gases and gallium scans are normal. (author). 9 refs, 2 tabs