DSA is used to diagnose many blood vessel diseases, including obstructive vascular diseases that are caused by blocks or narrowing in the lumen (inside) of arteries and veins, to diagnose a brain aneurysm (especially intracranial aneurysm), bleeding vessels, arteriovenous malformations (abnormal connections between arteries and veins), and to assess the vascularity (blood vessel systems) of cancerous tumours. DSA also provides a visual guide for interventional procedures needed to unblock or re-open occluded (blocked) arteries like angioplasty, arterial stent, nephrostomy and biliary procedures.