Background Liquid embolic agents are the preferred embolic material in endovascular treatment of pial and brain arteriovenous malformations and dural arteriovenous fistulas (DAVFs). There is little choice available in interventional neuroradiology practice other than two of the most commonly used liquid embolic agents—n-butyl cyanoacrylate and the Onyx liquid embolic system (ev3 Neurovascular, Irvine, California, USA). PHIL (Precipitating Hydrophobic Injectable Liquid) (Microvention, Inc California, USA) is a new liquid embolic agent, CE marked and available for clinical use in Europe.

Objective To present our preliminary experience using PHIL in treating cranial and spinal DAVFs.

Methods Between September 2014 and January 2015, eight patients, with five cranial DAVFs and three spinal DAVFs were treated with PHIL as the sole embolic agent used with intent to cure. Clinical presentation, location of DAVF, Borden type, fluoroscopic time, radiation dose, procedural time, injecting microcatheter used, volume of PHIL injected, complications, immediate angiographic data, premorbid and discharge modified Rankin Scale score, and any neurologic deficits were included in the analysis.

Results Seven patients were successfully treated with complete angiographic exclusion of the fistula in a single sitting. Treatment failed in one patient where only suboptimal microcatheter positioning could be achieved and PHIL failed to penetrate the fistula's nidus. Venous penetration was achieved in all other patients except one with a small fistula, but with adequate fistula penetration by the embolic material. No other technical complication or neurologic deterioration occurred in any of the patients.

Conclusions PHIL liquid embolic agent appears to be an excellent alternative embolic material with certain advantages compared with other available liquid embolic agents. Further studies are required to fully evaluate its safety and efficacy.