Chest Imaging

Superior vena cava obstruction

most commonly due to compression and invasion by bronchogenic carcinoma by means either of the primary tumour invading the mediastinum or of the lymph node metastases. The other causes include:

  • mediastinal malignant neoplasm, particularly metastatic breast or testicular neoplasms and lymphoma;

  • chronic mediastinitis;

  • thrombosis around a transvenous catheter; and

  • thrombosis due to Behcets disease or Hughes Stovin syndrome.

    Clinically, patients with superior vena cava obstruction may present with oedema, visible dilatation of the veins of the neck and anterior chest wall, dyspnoea, dysphagia or cerebral oedema. They may be also asymptomatic, depending on the degree of venous collateral formation. On the chest radiograph, enlargement of the azygos vein or the left superior intercostal vein may occasionally be visible. Venography shows the obstruction and collateral pathways and demonstrates intraluminal thrombus. It does not generally aid in identifying the cause of obstruction. CT scans show partial or complete filling defect of the superior vena cava as well as the responsible pathological process and venous collateral pathways. MRI may show the same features and has the ability to distinguish rapidly flowing blood from both slowly flowing blood and thrombus.

    PG