Objective: To analyze the high-resolution computed tomographic (HRCT) findings of IPF (interstitial pulmonary fibrosis), NSIP (nonspecific interstitial pneumonia) and COP (cryptogenic organizing pneumonia) retrospectively through quantification methods and to explore their distinguishing features.
Methods: Observers with no prior knowledge of the diagnosis evaluated the frequency, extent and distribution of various thin-section CT findings in 29 males and 17 females. The mean age was 50 ± 10 years old (range: 25 - 76). They had a histological diagnosis of IPF (n = 19), nonspecific interstitial pneumonia (NSIP) (n = 14) and cryptogenic organizing pneumonia (COP) (n = 13).
Results: Ground-glass opacity, thickening of bronchovascular bundles and interlobular septal thickening were frequent features of IPF and NSIP. The frequency and extent of honeycombing and bronchiolectasis were more found in IPF than in NSIP and COP (P < 0.05). The frequency and extent of air space consolidation were more found in COP than IPF (P < 0.05). There were more number of segments with traction bronchiectasis and less extent of air space consolidation in IPF than NSIP and COP. The number of segments with traction bronchiectasis was less in NSIP than that of IPF and COP.
Conclusion: The various subtypes of idiopathic interstitial pneumonias often have the distinguishing characteristics easily identified on HRCT. Bronchiolectasis and honeycombing are valuable features for IPF; air space consolidation is a valuable feature for COP. The features of NSIP are also found in both IPF and COP so that additional features are required for both.