CT findings of high-attenuation pulmonary abnormalities

Abstract

OBJECTIVES: To review the computed tomography (CT) findings of common and uncommon high-attenuation pulmonary lesions and to present a classification scheme of the various entities that can result in high-attenuation pulmonary abnormalities based on the pattern and distribution of findings on CT. BACKGROUND: High-attenuation pulmonary abnormalities can result from the deposition of calcium or, less commonly, other high-attenuation material such as talc, amiodarone, iron, tin, mercury and barium sulphate. CT is highly sensitive in the detection of areas of abnormally high attenuation in the lung parenchyma, airways, mediastinum and pleura. The cause of the calcifications and other high-attenuation conditions may be determined based on the location and pattern of the abnormalities within the lung parenchyma and knowledge of the associated clinical features. RESULTS: We have presented a diagnostic approach based on the presence and distribution of five main patterns of high-attenuation conditions on CT: (1) small hyperdense nodules, (2) large calcified nodules or masses, (3) high-attenuation linear or reticular pattern, (4) high-attenuation consolidation and (5) high attenuation extraparenchymal lesions. CONCLUSIONS: Some high-attenuation pulmonary abnormalities have characteristic CT findings suggesting the correct diagnosis. In other diseases, a combination of clinical features and radiological findings can significantly improve diagnostic accuracy.

Fig. 1

Residual postprimary pulmonary tuberculosis. Axial CT shows calcified granulomatous nodules in the left upper lobe (long arrows). Calcified nodules and the sequelae of parenchymal changes are also seen in the right upper lobe (short arrows)

Fig. 2

Metastatic pulmonary calcification in a 24-year-old man who had known chronic renal failure. Axial CT at a mediastinal and b parenchymal windows demonstrates bilateral centrilobular fluffy ground-glass nodular opacities that contain foci of calcification (arrows)

Fig. 3

Silicosis. Axial CT at the mediastinal window shows multiple calcified nodules with a conglomerate mass of fibrosis in the upper lobes (arrows)

Fig. 4

Barium aspiration. Axial CT at a mediastinal and b parenchymal windows shows extremely dense opacities in both lower lobes (arrows)

Fig. 5

Pulmonary alveolar microlithiasis. Axial CT at a mediastinal and b parenchymal windows shows diffuse numerous dense micronodules with calcified thickening of interlobular septa and subpleural cysts

Fig. 6

Hamartomas. Axial CT shows popcorn calcification in a benign solitary pulmonary nodule (arrow)

Fig. 7

Lung carcinoma. Axial CT shows eccentric calcification in a malignant mass, invading the mediastinum and right hilar region (arrows)

Fig. 8

Metastatic osteosarcoma. Axial CT shows parenchymal and pleural calcified metastatic lesions in both haemothoraces (arrows)

Fig. 9

Mucus plugging. Axial CT (lung window) shows calcified linear bronchial opacity in the right upper lobe (arrow)

Fig. 10

Amiodarone toxicity. Axial unenhanced CT at a mediastinal and b parenchymal windows shows dense lung consolidations in both lower lobes (arrows). Bilateral pleural effusion and pericardial effusion are also seen

Fig. 11

Calcified atelectasis. Axial unenhanced CT at the mediastinal window shows high-attenuation consolidations in both upper lobes (arrows)

Fig. 12

Endobronchial teeth secondary to trauma. Axial CT (bone window) demonstrates teeth in the right main and upper lobe bronchus (arrows)

Fig. 13

Pleural calcification secondary to empyema. Axial CT shows pleural calcification at the right haemothorax (arrow)

Fig. 14

Empyema necessitans after tuberculous empyema. Axial CT shows a calcified pleural mass, extending the extrapleural structures at the right haemothorax (arrows)

Fig. 15

Lymph node calcification. Axial CT shows right paratracheal calcified lymph nodes secondary to tuberculosis (arrow)