Chest Imaging

Thoracic isomerism

symmetrical morphology of the chest. It belongs to the heterotaxic syndromes and to the group of situs ambiguus. Left isomerism corresponds to a bilateral left-sidedness in which the bronchial and the pulmonary arterial anatomy of the right lung resembles the left with a bilateral hyparterial bronchial tree and bilateral bilobed lung. The right pulmonary artery crosses over the right main bronchus, measuring 1.7 to 2 cm from the carina. Commonly associated with polysplenia, complex congenital cardiac disease, partial anomalous pulmonary venous drainage, and azygos or hemiazygos continuation of the inferior vena cava, left isomerism can be an incidental isolated finding in adulthood. Right isomerism corresponds to a bilateral right-sidedness in which the bronchial and pulmonary arterial anatomy of the left lung resembles the right one with bilateral epiarterial bronchial tree and bilateral trilobed lung. Commonly associated anomalies are asplenia syndrome (Ivemark syndrome), complex congenital cardiac disease and abnormal pulmonary and systemic venous return. As left isomerism, right isomerism can also be encountered in adults with or without some anomalies described in the spectrum of heterotaxic syndromes such as ciliary dyskinesia syndrome and azygos continuation of the inferior vena cava. Also, see isomerism.

JR - MRJ