MR characteristics of progressive massive fibrosis

This study was performed to evaluate the static and dynamic magnetic resonance imaging (MRI) contrast enhancement pattern of progressive massive fibrosis (PMF) in coal workers' pneumoconiosis. Eighteen lesions in 12 patients were evaluated using a 1.5-T MR unit. T1-weighted FLASH images were obtained before and 0.5, 1, 2, 3, 4, 5, 7.5, 10, 12.5, and 15 minutes after injection of gadolinium diethylenetriamine penta-acetic acid (Gd-DTPA; 0.1 mmol/kg). Imaging findings, the contrast enhancing pattern, enhancement time curve, and the contrast uptake equivalent (CE; mmol/L) were evaluated. On T1-weighted images, 14 lesions showed high signal intensity, and four showed low signal intensity. On T2-weighted images, all lesions were of low signal intensity and were indistinguishable from aerated lung parenchyma. After contrast infusion, all lesions except two enhanced markedly. The time enhancement curve showed a marked, gradual increase in signal intensity up to 3 minutes, a subtle increase in signal intensity up to 7.5 minutes, and then a plateau until 15 minutes after Gd-DTPA injection. Characteristic MR findings of PMF in coal workers' pneumoconiosis include T1 high signal intensity, T2 low signal intensity, and marked postinfusion enhancement. The time enhancement curve shows a marked, gradual increase of signal intensity up to 3 minutes and plateau up to 15 minutes.