- Lobular or multilobular distribution of variable lung attenuation
- Three possible groups of etiologies: small-airway, vascular and infiltrative disease
- Additional findings are helpful to distinguish the three causes
- Dark or white areas are abnormal? Looking at size and number of vessels in both regions. If they are similar, the "white" is abnormal (meaning it is ground glass abnormality). If the size/number of vessels in dark areas are decreased, this is either small-airway or vascular pathology
- If the "white" is abnormal, look for differentials of ground glass opacity (GGO)
- If the "dark" is abnormal, look at expiratory phase scanning. If air trapping is present, this is small-airway disease. If there is no air trapping, this is likely vascular cause
- If expiratory scanning was not available, look at clinical features. Dyspnea, cough, wheezing and response to bronchodilators are common in patients with small-airway disease and infrequent in vascular lung disease
Stern EJ, et al. CT mosaic pattern of lung attenuation: distinguishing different causes. AJR 1995;165:813.