[CT and MR imaging of post-aortic left brachiocephalic vein]

The usefulness of CT and MR imaging (MRI) for the diagnosis of post-aortic left brachiocephalic vein (PALBV) is discussed. The subjects of the present study consisted of five patients with PALBV, two males and three females, aged four months to sixty years. Chest CT and MRI were performed as a follow-up study of other intrathoracic lesions in two cases, and for further examination of congenital heart diseases in two infant cases. The other patient underwent both CT and MRI to evaluate sporadic chest pain. Therefore, all PALBV were found incidentally. PALBV passes below the aortic arch in front of the trachea, draining the superior vena cava behind the ascending aorta. This finding was particularly well documented on consecutive coronal sections on MRI. In patients with intrathoracic malignant or specific inflammatory lesion, differentiation between PALBV and lymphadenopathy is necessary for treatment. From our experience, marked enhancement on CT and no signal intensity on MRI in PALBV could differentiate this anomaly from mediastinal lymphadenopathy. In two infantile cases with congenital cardiovascular anomalies such as tetralogy of Fallot, right aortic arch and pulmonary arterial stenosis, MRI was found to be superior to CT in demonstrating these anomalies.