Application of 99mTc-DTPA aerosol in evaluation of pulmonary epithelial permeability.

Measuring of the rate of radioactivity decrease of inhaled 99mTc-DTPA aerosol may detect disorders of alveocapillary membrane integrity. The study included 21 patients (11 non-smokers and 10 smokers) suffering from different pulmonary diseases (pulmonary embolism - PE; chronic obstructive pulmonary disease - COPD; pneumonia - PN; occupational diseases - OD) in order to detect disorders of pulmonary epithelial permeability (PEP) and 2 healthy individuals (non-smokers) with normal findings (NF). DTPA was labelled using the standard procedure with 1480 MBq 99mTc in 1 ml of physiologic saline. Patients with nasal obstruction inhaled aerosol for 2.5 min. particle size 0.8 micron produced in a nebulizer connected to O2. After that gamma scintillation camera and computer were used for data acquiring in dynamic mode. After that ventilation and perfusion scintigraphy of the lungs was performed in four standard projections. Data processing was conducted with ROI drawing after both lungs on the added image. Clearance value was expressed in T1/2 (min), while the curves had monoexponential shape in all patients. In the non-smoking group mean clearance value for both lungs in patients suffering from PE, COPD and PN did not differ from NF. Clearance in the part of the lungs affected with disease (pneumonia, embolism) was faster than in healthy pulmonary tissue. In sick smokers, however, mean pulmonary clearance value was higher than in non-smokers, irrespective of the type of disease. Pulmonary clearance in individuals suffering from occupational diseases was also accelerated, irrespective of the fact whether the patients smoked or not.