Quantitative assessment of pulmonary perfusion using dynamic contrast-enhanced CT in patients with chronic obstructive pulmonary disease: correlations with pulmonary function test and CT volumetric parameters

Abstract

Background

Pulmonary function test (PFT) is commonly used to help diagnose chronic obstructive pulmonary disease (COPD) and other lung diseases. However, it cannot be used to evaluate regional function and morphological abnormalities.

Purpose

To quantitatively evaluate pulmonary perfusion imaging using dynamic contrast-enhanced (DCE) computed tomography (CT) and observe its correlations with PFT and CT volumetric parameters in COPD patients.

Material and Methods

PFT and CT pulmonary perfusion examination were performed in 63 COPD patients. Perfusion defects were quantitated by calculating the CT value ratio (R_HU) between perfusion defects (HU_defect) and normal lung (HU_normal). Volumetric CT data were used to calculate emphysema index (EI), total lung volume (TLV), and total emphysema volume (TEV). Emphysematous parenchyma was defined as the threshold of lung area lower than –950 HU. Correlations between R_HU and TLV, TEV, EI, and PFT were assessed using Spearman correlation analysis.

Results

The positive rate of perfusion defects on CT perfusion images was higher than that of emphysema on CT mask images (χ2 = 17.027, P < 0.001). The Spearman correlation test showed that R_HU was positively correlated with FEV₁ (R = 0.59, P < 0.001), FEV₁% Predicted (R = 0.61, P < 0.001), FVC (R = 0.47, P = 0.002), and FEV₁/FVC (R = 0.65, P < 0.001), and negatively correlated with EI (R = –0.67, P < 0.001).

Conclusion

CT perfusion imaging is more sensitive in detecting emphysema that is inconspicuous on CT images. R_HU is correlated with PFT and CT volumetric parameters, suggesting that it is more sensitive in detecting early COPD changes and may prove to be a potential predictor of focal lung function.

Keywords

Chronic obstructive pulmonary disease emphysema pulmonary function test computed tomography

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