A NOVEL-APPROACH TO FLOW QUANTIFICATION IN BRAIN ARTERIOVENOUS-MALFORMATIONS PRIOR TO ENBUCRILATE EMBOLIZATION - USE OF INSOLUBLE CONTRAST (ETHIODOL DROPLET) ANGIOGRAPHY

Object. Successful therapeutic embolization of arteriovenous malformat ions (AVMs) of the brain with liquid polymers (glues) requires precise knowledge of highly variable AVM structure and flow velocities and tr ansit times of blood through the AVM nidus. The goal of this study was to improve AVM flow measurement and visualization by the substitution of the insoluble Ethiodol (ethiodized oil) contrast agent for the sol uble contrast media normally used in angiographic studies. Methods. Be fore enbucrilate embolization of 24 AVM feeding pedicles in 13 patient s, standard contrast medium was superselectively injected into each ta rget pedicle, followed by infusion of 20 mu l of Ethiodol microdroplet s. Transport of contrast material was assessed using high-speed biplan e pulsed digital subtraction angiography (DSA) operating at 15 frames per second. The mean blood flow transit times through AVMs after admin istration of Ethiodol were found to be approximately half as long as i n those measured after injection of soluble contrast materials (0.22 /- 0.10 seconds compared with 0.46 +/- 0.19 seconds [mean +/- standard deviation]; p < 0.0001). The discrete Ethiodol microdroplets travel w ith the core flow, more closely approximating the dynamic behavior of enbucrilate, allowing the AVM structure to be traced with high spatial and temporal resolution. There were no inadvertent vessel occlusions or pulmonary complications related to the use of Ethiodol for DSA. Con clusions. Because of diffusion and convection, forces that decrease co ncentration, visualization of the contrast front is reduced, often res ulting in deceptively long transit times when soluble contrast materia ls are used. Overestimation map prove dangerous when planning emboliza tions. The Ethiodol droplet DSA method provides accurate transit time measurements and precise, detailed, and dynamic AVM visualization. Fur ther development of this method will improve the safety and precision of AVM treatments.