Chest Imaging

Intralobar sequestration

anomaly that is often not discovered in early childhood, but rather in older children and young adults. It is more common at the left lung base, sometimes bilaterally and rarely at the upper lobes. From a therapeutic viewpoint, intralobar sequestration must be separated into two distinct anomalies:

  • The connection of sequestration with the bronchial tree or the pulmonary artery is abnormal. The normal lung and the sequestration lung are both covered by a common pleura. The aberrant pulmonary tissue may be a solid or cystic mass. It is supplied by one or multiple systemic arteries arising from the thoracic and/or abdominal aorta. The venous return is in the left atrium. The only treatment is surgical.

  • The connection between the sequestration and the bronchial tree and lung parenchyma is normal. The only abnormality is the systemic artery arising from the aorta, responsible for a left to left shunt via the pulmonary vein to the left atrium.

    There is no abnormal lung opacity, the only feature sometimes seen on the chest radiograph (and more often on an incidental CT scan), is the abnormal course and size of the systemic artery(ies) (Fig.1). Previously called Pryce's type I or purely vascular intralobar sequestration this anomaly is also described as arterial supply to normal basal segments of the lung. The clinical symptoms are due only to the abnormal vessel (haemoptysis, aneurysm, thrombosis, cardiac failure, rupture). The treatment may be endovascular in suitable cases. In patients with a large systemic artery the risks of acquired arterial complications including atheromatous aneurysm, mycotic aneurysm, thrombosis and rupture, surgical treatment must be considered.

    JR - MRJ

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    Fig.1

    Intralobar sequestration of the right lower lobe. Helical CT angiography with volume rendering technique. A single large systemic artery arising from the thoracic descending aorta perfuses the sequestrated parenchyma including two nodular calcifications.
    Intralobar sequestration, Fig.1