Clearance of technetium-99m-DTPA and HRCT findings in the evaluation of patients with Idiopathic Pulmonary Fibrosis

BACKGROUND Clearance of inhaled technetium-labeled diethylenetriamine pentaacetate (99mTc-DTPA) is a marker of epithelial damage and an index of lung epithelial permeability. The aim of this study was to investigate the role of 99mTc-DTPA scan in patients with Idiopathic Pulmonary Fibrosis (IPF). Our hypothesis is that the rate of pulmonary 99mTc-DTPA clearance could be associated with extent of High Resolution Computed Tomography (HRCT) abnormalities, cell differential of bronchoalveolar lavage fluid (BALF) and pulmonary function tests (PFTs) in patients with IPF. METHODS We studied prospectively 18 patients (14 male, 4 female) of median age 67 yr (range 55-81) with histologically proven IPF. HRCT scoring included the mean values of extent of disease. Mean values of these percentages represented the Total Interstitial Disease Score (TID). DTPA clearance was analyzed according to a dynamic study using a Venticis II radioaerosol delivery system. RESULTS The mean (SD) TID score was 36 +/- 12%, 3 patients had mild, 11 moderate and 4 severe TID. Abnormal DTPA clearance half-time (t1/2 < 40 min) was found in 17/18 (94.5%) [mean (SD) 29.1 +/- 8.6 min]. TID was weakly correlated with the DTPA clearance (r = -0.47, p = 0.048) and with % eosinophils (r = 0.475, p = 0.05). No correlation was found between TID score or DTPA and PFTs in IPF patients. CONCLUSION Our data suggest that 99mTc-DTPA lung scan is not well associated with HRCT abnormalities, PFTs, and BALF cellularity in patients with IPF. Further studies in large scale of patients are needed to define the role of this technique in pulmonary fibrosis.