Determination of blood flow velocity and transit time in cerebral arteriovenous malformation using microdroplet angiography.

Advancement in imaging and biomedical technology has improved the use of catheter-based transarterial embolization (occlusive therapy) of cerebral arteriovenous malformations (AVMs). Among a variety of embolic agents, liquid adhesives (acrylates) have proven to be more successful in permanent obliteration of AVMs. The use of liquid adhesives requires the experience and skill of the operator. However, acquiring accurate information on blood flow and transit times through the AVM prior to embolization can optimize the treatment. In addition, knowledge of the polymerization time and behavior of the acrylate enables a complete and safe occlusion of the arteriovenous transition within the AVM nidus. Standard commercially available iodine-based contrast agents seem to be insufficient to determine AVM transit times from angiograms. For a more accurate assessment of AVM transit times, the use of a nonsoluble contrast agent (Ethiodol) and a high-speed digital subtraction angiography (DSA) is suggested. Small amounts (<20 microl) of Ethiodol were infused to create microdroplets and traced using DSA at 15 fps. Transit time, defined as the time interval required for a droplet to reach the venous part of the AVM after being flushed from the tip of the catheter, could be accurately calculated. Postprocessing was used to calculate trajectories and velocities of microdroplets.