Technetium 99m-diethylene triamine penta-acetic acid aerosol clearance in the evaluation of pulmonary involvement in sickle cell disease

BACKGROUND: Pulmonary clearance of inhaled technetium (Tc) 99m-labeled diethylene triamine penta-acetic acid (DTPA) aerosol is a sensitive non-invasive marker of alveolar permeability and patients with interstitial lung diseases show enhanced clearance. However, a previous study in adult patients with diabetes mellitus showed delayed clearance. OBJECTIVES: To investigate DTPA clearance in steady-state, otherwise healthy adult sickle cell disease (SCD) patients and correlate it with pulmonary function tests (PFTs), hematologic and clinical parameters. MATERIALS AND METHODS: The subjects were randomly selected from the Hematology Clinic of Mubarak Hospital, Kuwait. Hematologic and pulmonary function data were collected with standard methods. DTPA radio-aerosol clearance studies were performed using ultrafine nebulizer containing 35 mCi (1295 MBq) of Tc 99m-DTPA in its reservoir and t(1/2) clearance in minutes was determined. Average values for both lungs were calculated and compared with normal values for our population. RESULTS: Forty-three subjects (24 SS and 19 S-beta(0)thal) aged between 16 and 45 yr (mean of 27.1 +/- 9.7) were studied. Twenty-two subjects (51.2%) had delayed, while only 10 (23.3%) showed enhanced DTPA clearance. Patients with enhanced clearance showed better PFTs than those with normal or delayed clearance. There was significant negative correlation of DTPA clearance with forced expiratory volume in 1 s, forced vital capacity and total lung capacity and significant positive correlation with age. CONCLUSIONS: Majority of adult SCD patients have delayed DTPA clearance unlike in inflammatory lung diseases, but similar to diabetes mellitus. DTPA clearance may be a useful modality for monitoring pulmonary involvement in SCD.