High CT attenuation values of a benign pulmonary nodule

Computed tomography (CT) is thought to be a reliable predictor of the benignancy of pulmonary nodules when high attenuation values can be demonstrated. However, the cause of increased attenuation has not been proven. A pulmonary nodule evaluated initially by CT and subsequently followed for 4 years has developed central calcification by conventional tomography. This observation supports the contention that elevated CT attenuation values are the result of microscopic calcification.