Use of the delayed mask for improved demonstration of aneurysms on intraarterial DSA.

PURPOSE We retrospectively explored the use of the delayed mask technique for intraarterial digital subtraction angiography (IADSA) to demonstrate the anatomy of aneurysm necks. METHODS The delayed mask technique was utilized in 22 patients who had craniotomies for aneurysms demonstrated at angiography. The operative notes were compared to the angiographic findings of both the traditionally masked IADSA and the delayed mask IADSA. In addition, an in vitro model was constructed to examine the relationship between the size of the aneurysm neck and the ability to indirectly define its anatomy by demonstrating the flow jet. RESULTS In 12 of 22 cases, the delayed mask technique demonstrated a systolic jet that was not demonstrated by traditional subtraction techniques. In nine of 12 cases, the delayed mask technique gave more specific information regarding the size, location, and orientation of the aneurysm neck. CONCLUSION The delayed mask technique can add important information regarding the anatomy of aneurysm without adding time or risk to the procedure.