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 Tl-, 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 biopsy. Parenchymal opacification on MR usually indicates the presence of potentially reversible disease, while reticulation usually indicates irreversible fibrosis.