[Identification of lung architecture using HRCT]

The pulmonary interstitium is divided into different compartments, with the secondary pulmonary lobule representing the smallest subunit surrounded by connective tissue. Identification of the lobular architecture is a prerequisite for categorizing the broad spectrum of pulmonary interstitial diseases into distinct patterns. High-resolution computed tomography (HRCT) patterns comprise reticular and nodular opacities, ground-glass opacities, and consolidation. Air trapping and emphysema are associated with decreased pulmonary attenuation. The features of these patterns are derived from the anatomic basis and are linked with typical differential diagnoses, although the nonspecificity of the different patterns should be kept in mind. A main objective is to focus on mixed patterns.