Role of magnetic resonance in the diagnosis of subclavian steal syndrome.

Subclavian steal syndrome (SSS) is a condition secondary to an occlusion in the proximal subclavian artery, in which the blood supply to the arm is sustained by reversal of flow in the ipsilateral vertebral artery. We describe two similar cases of SSS due to a right aortic arch with isolated left subclavian artery. Diagnosis was made with magnetic resonance imaging (MRI) and angiography (MRA), which was confirmed by Doppler ultrasound and X-ray angiography. The exact anatomic relationships of the vascular structures were well demonstrated on contrast-enhanced MRA, while flow reversal was documented on flow-encoded MRI datasets. We conclude that the combination of different MRI modalities forms an accurate and reliable alternative in the diagnostic workup of patients with suspected SSS.