High-resolution CT evaluation of ground-glass opacity in diffuse lung disease

Ground-glass opacity of the lung is often demonstrated on high-resolution CT (HRCT) in various diffuse lung diseases. Ground-glass opacity generally results from minimal thickening of the alveolar interstitium or partial filling in the alveolar spaces. We classify diffuse infiltrative lung diseases into two clinical categories, namely, noninfectious and infectious lung disease. In noninfectious lung disease, although ground-glass opacity can be observed as an isolated finding, it is commonly observed to be combined with other findings such as centrilobular micronodules, interlobular septal thickening, and cystic air-spaces. These associated findings may be important for the differential diagnosis. Ground-glass opacity may also be seen as a consequence of increased capillary blood volume in redistribution of blood flow. This condition of hemodynamic origin is observed in chronic obstructive pulmonary disease, airway disease, and vascular lung disease. Although ground-glass opacity is a nonspecific finding, it can suggest a specific diagnosis in certain clinical circumstances or indicate a potentially treatable disease. Therefore, accurate recognition and differential diagnosis of ground-glass opacity are important. (author) 50 refs