Clearance rate of inhaled 99mTc-DTPA in systemic sclerosis

Lee, Myung Kwon; Kang, Young Mo; Bae, Gi Bum; Park, Jee Hyun; Lee, Jong Myung; Lee, Jae Tae; Kim, Nung Soo

Abstract

BACKGROUND: We measured the clearance rate of inhaled 99mTc-diethyl triaminepentaacetic acid (DTPA) aerosol in patients with systemic sclerosis. We also investigated its correlation with respiratory function test and acute phase reactant proteins.
METHODS
Ten patients with systemic sclerosis, ten patients with rheumatoid arthritis, and ten healthy controls were included. Dynamic scintigrams (20 seconds/frame, up to 30 minutes) were obtained following inhalation of 99mTc-DTPA aerosol through a radioaerosol delivery system. The time to half clearance (T1/2) was calculated from the time-activity curves. High resolution computed tomography, pulmonary function test and laboratory tests such as ESR, CRP, and complement (C3/C4) were performed.
RESULTS
1) Mean T1/2 values of 99mTc-DTPA clearance after inhalation were 28.1+/-3.8, 57.9+/-20.9, and 64.3+/-13.0 minutes in systemic sclerosis, rheumatoid arthritis and normal controls, respectively. Mean T1/2 value in systemic sclerosis was significantly reduced compared with those of rheumatoid arthritis group (p<0.001) and normal controls (p=0.001).2) No significant correlations were found between mean T1/2 and FEV1/FVC, FVC or DLco in patients with systemic sclerosis. 3) There was no significant correlation between mean T1/2 and ESR or CRP in patients with systemic sclerosis. And in patients with rheumatoid arthritis, mean T1/2 value correlated significantly with ESR and CRP.
CONCLUSION
The clearance rate of inhaled 99mTc-DTPA was significantly increased in patients with systemic sclerosis and had no significant correlation with pulmonary function test and acute phase reactants, but was found to have significant correlations with ESR and CRP in patients with rheumatoid arthritis.