Importance of ground-glass attenuation in chronic diffuse infiltrative lung disease: pathologic-CT correlation.

PURPOSE: To correlate areas of ground-glass attenuation at computed tomography (CT) with findings at open lung biopsy in chronic diffuse lung disease. MATERIALS AND METHODS: The cases of 26 patients were included on the basis of (a) extensive areas of ground-glass attenuation as the predominant (n = 17) or exclusive (n = 9) abnormality at CT in the absence of honeycombing and (b) histologic evaluation at open lung biopsy. Severity of ground-glass attenuation was scored in the lobe sampled at biopsy, with separate analysis of associated lung changes. RESULTS: Correlation of CT with histologic findings at the 37 biopsy sites demonstrated that ground-glass attenuation corresponded to inflammation in 24 (65%) cases and to fibrosis in 13 (54%) cases. Eleven of the 13 patients (85%) with fibrosis had traction bronchiectasis or bronchiolectasis. These findings were not present in any of the patients with inflammation. CONCLUSION: In patients with chronic diffuse infiltrative lung disease, areas of ground-glass attenuation not associated with traction bronchiectasis or bronchiolectasis are a reliable indicator of inflammation.