Increased Lung Uptake of Technetium-99m Hexamethylpropylene Amine Oxime in Diffuse Infiltrative Lung Disease

Abstract

Background: Diffuse infiltrative lung disease (ILD) is a heterogeneous group of disorders which predominantly affect the lung parenchyma and spare the airway. Objective: To assess pulmonary vascular endothelium damage in ILD, the lung uptake of technetium-99m hexamethylpropylene amine oxime (^99mTc-HMPAO) was determined. Methods: In 20 ILD patients and 25 controls without ILD, the lung uptake of ^99mTc-HMPAO was measured. Anterior lung imaging, including a large part of the liver, was made 10 min after intravenous injection of 20–25 mCi of ^99mTc-HMPAO. Regions of interest covered the liver and lung to calculate the lung/liver uptake ratios. The 20 ILD patients included 10 patients with clinically manifest pulmonary disease (group 1) and 10 asymptomatic patients (group 2). All of the study subjects had normal pulmonary function test results. Results: The mean lung/liver uptake ratio in the 25 controls without ILD (0.36 ± 0.10) was significantly lower than that in the 20 ILD patients (0.97 ± 0.61). In addition, the mean lung/liver uptake ratio in the 10 ILD patients with clinically manifest pulmonary disease (1.45 ± 0.51) was higher than that of the other 10 asymptomatic ILD patients (0.49 ± 0.09). Conclusions: Our results indicated that determining the lung/liver uptake ratio on ^99mTc-HMPAO lung imaging should be an objective method to assess subclinical pulmonary damage in ILD patients.