Pulmonary alveolar microlithiasis: high-resolution CT and MR findings.

We report the high-resolution CT (HRCT) and MR findings in a case of pulmonary alveolar microlithiasis. HRCT revealed that the black pleural line on a chest radiograph was caused not by subpleural cysts but by a fat-dense layer between ribs and the calcified parenchyma. MRI showed both lower zones with diffusely increased signal intensity on T1-weighted images. We speculated it was caused by the accumulation of small-sized calcific particles.