Mediastinum Shift
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Decreased Lung Volume (pulls mediastinum toward lesion) |
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Atelectasis |
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Postoperative (lobectomy, pneumonectomy) |
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Increased Lung Volume (pushes mediastinum away from lesion) |
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Foreign body obstructing large bronchus |
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Bronchiolitis obliterans |
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Bullous Emphysema |
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Interstitial Emphysema |
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Bronchogenic Cyst |
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Large Masses (pulmonary mediastinum) |
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Pleural Space Abnormalities (Pushes mediastinum away from lesion) |
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Unilateral pleural effusion |
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Tension pneumothorax |
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Diaphragmatic hernias or masses |
Lesions with a Subtle Mediastinum Shift:
1.Other chest X-ray changes include: elevation of the diaphragm, crowding of the ribs and contralateral hyperlucency
2.Expiratory Film: If one side remains unchanged that is the involved side. In other words no change in the lung volume after exhalation represents a defect.
3.Lateral Decubitus Film: Persistence of the mediastinum shift. Over-expanded side that remains over-expanded in the down position suggests endobronchial lesion.
Large Volume change without tracheal shift:
Suggest fibrosis or tumor burden