Evaluation of Lung Permeability in Patients with Connective Tissue Disease using 99mTc-DTPA Aerosol Scintigraphy

Hong, Yeong Hoon; Ryu, Dong Han; Kim, Sung Dong; Park, Ki Do; Lee, Eun Yeung; Cho, Ihn Ho; Lee, Choong Ki; Lee, Hyong Woo

Abstract

OBJECTIVE
The association between the connective tissue diseases and lung diseases is well established. DLCO and 99mTc-DTPA aerosol scintigraphy are used for evaluation of the alvelolar-capillary permeability. This study evaluated the changes in permeability of alveolar-capillary membrane and the utility of the 99mTc-DTPA aerosol clearance to detect lung involvement in patients with connective tissue diseases.
METHODS
The patient group consisted of the patients with any proven connective tissue diseases (27 rheumatoid arthritis, 17 systemic lupus erythematosus, 7 other connective tissue diseases) and the control group consisted of healthy 12 persons. The patients and controls were non-smokers and had no concomitant diseases that could affect the result (diabetes, any lung diseases etc). Chest X-ray, spirometric measurements of lung volumes, flow idices, diffusing capacities and 99mTc-DTPA aerosol scintigraphy were performed in the patient group and control group. 99mTc-DTPA aerosol (1110 MBq) was used with the aero-vent jet nebulizer as a lung delivery system. Patients in sitting position inhaled for 5 minutes at normal tidal oral breathing, Scintigraphic data were recorded using the Picker Prism 2000 gamma cammera, 15 frames of the lung were obtained as the area of interest anteriorly and posteriorly (120 msec at each frame, for 30 minutes). 99mTc-DTPA clearance rate was calculated as the time to half clearance (T1/2).
RESULTS
The mean clearance rates of 99mTc-DTPA were 64.0+/-24.1 min (RA 70.7+/-26.2 min, SLE 61.6+/-14.0 min, Others 43.9+/-24.7 min), and 47.0+/-10.3 min in the patient group and the control group respectively. Significant correlation was not found between the pulmonary clearance rate of 99mTc-DTPA and other parameters (disease duration, ESR, CRP, DLCO and FEV1/FVC).
CONCLUSION
99mTc-DTPA clearance in the patient group (RA, SLE, others) was significantly decreased than that in control group (p<0.05). In the patient group with normal chest X-ray, 99mTc-DTPA clearance in the connective tissue disorders was significantly decreased than control group (p<0.05). We suggest that 99mTc-DTPA aerosol scintigraphy may be one of useful technique for early detection of the lung involvement in the connective tissue disorders.