A pilot trial of quantitative Tc-99m HMPAO and Ga-67 citrate lung scans to detect pulmonary vascular endothelial damage and lung inflammation in patients of collagen vascular diseases with active diffuse infiltrative lung disease.

Diffuse infiltrative lung disease (ILD) includes a heterogeneous group of disorders predominantly affecting lung parenchyma and sparing the airway. To assess the degree of pulmonary vascular endothelial damage in active ILD, lung/liver uptake ratios (L/L ratio) on technetium-99m hexamethylpropylene amine oxime (Tc-99m HMPAO) lung scan were determined in 30 patients with active ILD. Meanwhile, the gallium-67 citrate (Ga-67) uptake index (GUI) on Ga-67 lung scan was used to evaluate the severity of lung inflammation in active ILD. In this study, high-resolution CT (HRCT) was used to evaluate disease activity in ILD. The results show statistically significant differences between normal controls and patients with active ILD as shown in L/L ratios and GUI. However, when the patients were divided into two groups of 15 patients with normal chest X-ray findings and 15 with abnormal X-ray findings, there was no significant difference in those parameters. In addition, there was no statistically significant difference between the groups in HRCT scoring. No good correlation between the degree of pulmonary vascular endothelial damage and the severity of lung inflammation was found. In addition, there were no good correlations between HRCT scoring vs GUI and HRCT vs L/L ratio in different study subgroups. In conclusion, L/L ratios on Tc-99m HMPAO and GUI on Ga-67 lung scans differ from chest X-ray findings and have the potential to detect the degree of pulmonary vascular endothelial damage and severity of lung inflammation in active IDL. However, the relationships between HRCT scoring, GUI, and L/L ratio in patients with collagen vascular diseases and active ILD are not significant.