GA-67 LUNG IMAGING AND PULMONARY CLEARANCE OF TC-99M-DTPA AEROSOL IN PATIENTS WITH AMIODARONE PNEUMONITIS

The aim of this study was to compare gallium-67 citrate lung imaging w ith the pulmonary clearance of Tc-99m-DTPA (technetium 99m diethylenet riaminepentaacetic acid) in 9 patients with amiodarone pneumonitis (8 males and 1 female, aged 58 to 76 years). The diagnosis of amiodarone pneumonitis was based on clinical and radiological grounds in all pati ents, and histological changes in seven. The mean values for the effec tive half-life of the pulmonary clearance of Tc-99m-DTPA aerosol were below the normal range in all 9 patients, and lower than the values ob tained previously for patients on a long-term amiodarone regimen witho ut side effects. Positive gallium-67 accumulation was demonstrated in 7 of the 9 patients. Two patients had negative gallium-67 imaging and increased alveolar-capillary Tc-99m-DTPA clearance; with corticosteroi d therapy and discontinuation of amiodarone, their radiological change s and clearance became normal within 120 days. In conclusion, when com pared to gallium-67 lung imaging, the Tc-99m-DTPA aerosol clearance is more advantageous because it is a much faster test than the gallium s can. This is essential for those patients suspected of amiodarone pneu monitis who need specific therapy as soon as possible. Moreover, the T c-99m-DTPA aerosol clearance test appears to be a more useful diagnost ic tool because it is positive even in those patients who have normal gallium-67 lung imaging.