Mri of infiltrative lung disease: Comparison with pathologic findings

Objective: Our goal was to compare MRI with pathologic findings in patients with chronic infiltrative lung disease. Materials and Methods: The study included 22 consecutive patients who had MRI and lung biopsy performed within 21 days (median 4 days). Fifteen patients had open lung biopsy: Five with idiopathic pulmonary fibrosis, three with extrinsic allergic alveolitis, and seven with miscellaneous conditions. Seven patients had transbronchial biopsy: four with sarcoidosis and three with miscellaneous conditions. All patients had 1.5 T MRI with cardiac-gated T1-, proton density-, and T2-weighted SE sequences. Results: The predominant patterns of abnormality seen on MR included parenchymal opacification (n = 12), parenchymal opacification and reticulation (n = 2), reticulation (n = 3), nodularity (n = 3), and interlobular septal thickening (n = 1); normal findings were found in 1. The 14 patients with parenchymal opacification included 9 with ground-glass intensity and 5 with consolidation. In 12 of these 14 patients the parenchymal opacification represented an active inflammatory process including alveolitis, pneumonia, and granulomatous inflammation, while in 2 patients it represented fibrosis. Reticulation was shown to represent fibrosis in five of five cases. The three patients with nodules had sarcoidosis. Conclusion: The MR findings correlate closely with those seen on lung bi-opsy. Parenchymal opacification on MR usually indicates the presence of potentially reversible disease, while reticulation usually indicates irreversible fibrosis.