Increased pertechnegas lung clearance in interstitial lung disease

Interstitial lung disease (ILD) is characterized by inflammation within the alveolar walls and interstitium of the lungs. This causes increased alveolar-capillary membrane permeability. The diagnosis is made by clinical features, chest roentgenography, lung function tests, and high-resolution CT, and it is confirmed by lung biopsy. Radionuclide aerosol tracers such as Tc-99m DTPA show increased lung clearance in ILD. The clearance rate of microaerosol pertechnegas (modified Technegas) from the lungs in the assessment of ILD was evaluated.

Thirty-two patients (22 with ILD and 10 with non-ILD) were evaluated with pertechnegas. Pertechnegas is formed by adding 3% oxygen to technegas, a microaerosol ventilation agent. Regions of interest were then drawn around the lungs, and clearance rates were determined from the best exponential fit.

The mean clearance rate of pertechnegas was significantly increased in ILD and measured 5.78 +/- 2.2 minutes compared with non-ILD, which measured 8.53 +/- 2.42 minutes (P < 0.001). The sensitivity and specificity rates of pertechnegas clearance (less than 8 minutes) in ILD were 90% and 60%, respectively. When combined with chest roentgenography, the sensitivity and specificity rates increased to 100% and 90%, respectively.

Pertechnegas is highly effective in determining the presence of active ILD. It differentiates between active ILD and non-ILD, and it is highly sensitive and specific when combined with chest roentgenography. Its potential role in the management of ILD merits further investigation.