Onyx is a mixture of ethylene vinyl alcohol (EVOH) and tantalum dissolved in dimethyl sulfoxide (DMSO). Onyx is used in endovascular neuroradiology for embolization of blood vessels. Onyx is a nonadhesive liquid embolic agent with a paste-like consistency. After administration, the DMSO is absorbed transmurally, leaving behind the mixture of tantalum and EVOH. The tantalum admixture makes Onyx visible on fluoroscopic imaging. The higher the EVOH content, the higher the viscosity of Onyx. A distinction is made between Onyx-18 and Onyx-34[^1].
Image of Onyx-18 and Onyx-34.
Onyx-18
Onyx-18 has an EVOH content of 6% and a viscosity of 18 cST according to the manufacturer's information from Medtronic.
Onyx-34
Onyx-34 has an EVOH content of 8% and a viscosity of 34 cST according to the manufacturer's information from Medtronic.
Imaging artifacts
In CT imaging, patients who have undergone embolization with Onyx develop imaging artifacts.
Imaging artifact on CT caused by the administration of Onyx-18.