Here is a case of subclavian artery pseudoaneurysm with typical imaging criteria. The patient was a long stay polytraumatic, and an iatrogenic injury was suspected to be the cause of pseudoaneurysm (arterial catheterization during a trial of central venous access). A plain CT study of the neck was done first for airway assessment and the lesion was discovered incidentally and a duplex study was recommended.

An important tip here is that if any detected mass-like lesion with unknown nature, the vascular possibility must be excluded first especially if the lesion is related to the vascular structures to avoid catastrophic bleeding with any intervention.  

Ultrasound contribution by Dr. Somia Elbadawy