We spoke to Dr. Romaric Loffroy to to find out more on the liquid agents hands-on device training that took place at CIRSE 2022.
Liquid agents hands-on device training
Liquid embolisation is increasingly being used for peripheral applications. High embolic efficiency and good clinical results are the main strengths of liquid embolic agents. However, management of and practice with liquid embolics are different and a bit more complex than when using conventional coils or particles. Liquid embolics can generally be classified into three main groups; cyanoacrylates (glue), non-adhesive DMSO-based embolics, and sclerosants. Despite their similarities, these products also demonstrate some major differences. Among cyanoacrylates, there are also some distinctions IRs should be aware of.
Only a few cyanoacrylates for endovascular use are officially available on the worldwide market: Glubran2® and Trufill® have the CE mark and FDA approval, respectively. Histoacryl® has neither the CE mark nor FDA approval for endovascular interventions, for which it is widely used off-label. Its faster polymerization rate compared to other glues makes Histoacryl® more challenging to use. Glubran®2 has the advantage of being very inexpensive compared to Trufill® (about 100 € versus 2,000 $ per 1 mL vial) and available worldwide, whereas Trufill® is used only in the United States. A new α-hexil-cyanoacrylate glue (MagicGlue®, Balt Extrusion, Montmorency, France), known as Purefill® (Peters Surgical, Bobigny, France), was recently developed and has exhibited short- and long-term occlusive efficacy and histopathologic responses similar to those seen with Histoacryl® and Glubran®2. However, α-hexil-cyanoacrylate seems to have less adhesive strength compared to Histoacryl® and Glubran®2. Cyanoacrylate has a number of advantages, although there is a learning curve for the operator [1,2]. The liquid polymerizes rapidly upon contact with blood. However, dilution in Lipiodol Ultra Fluid (UF) (Guerbet, Aulnay-sous-Bois, France) decreases the speed of polymerization, thus allowing complete and still rapid devascularization of the vascular bed. The addition of Lipiodol UF also allows monitoring of the flow of embolic material and detection of possible reflux along the microcatheter. Contrary to microparticles and other liquid agents, cyanoacrylate adheres to the vessel wall, inducing substantial inflammation and remodeling that contribute to lumen obliteration. Another advantage of a glue/Lipidol mixture is that the fast polymerization, as well as the radiopaque feature, potentially decreases the risk of non-target embolisation as compared to microparticles.
DMSO-based embolics include ethylene-vinyl-alcohol-copolymer (EVOH) and iodinated polyvinyl alcohol polymer ether. EVOH-based agents include Onyx™ (Medtronic, USA), Squid (Balt, France) and Precipitating Hydrophobic Injectable Liquid (PHIL) (Microvention, Japan), developed primarily for use in intracranial aneurysms and vascular malformations . Onyx is the most widely used and discussed in more detail. Iodinated polyvinyl alcohol polymer ether is represented by Easyx™, a novel copolymer liquid embolic agent without tantalum, allowing reduced CT artifacts on imaging follow-up . Onyx™ and Squid are cohesive liquid embolic agents, composed of ethylene-vinyl alcohol (EVOH) copolymer dissolved in dimethyl sulfoxide (DMSO) with suspended micronized tantalum powder. When the DMSO solvent diffuses away, Onyx or Squid forms a spongy elastic embolus. Onyx™ is supplied in ready-to-use vials and several formulations are available that differ in the concentration of copolymer and tantalum content. Onyx 34 (EVOH 8%) is more viscous and allows for more controlled injection in higher flow targets, whereas Onyx 18 (EVOH 6%) will travel more distally and penetrate deeper into the target lesion. Onyx 34L has a lower tantalum concentration resulting in less streak artifact on CT. Onyx is delivered through a microcatheter under fluoroscopic control. Squid has one more dilution (Squid 12) which allows deeper penetration.
Sclerosants include alcohol, polidocanol, sotradecol, bleomycin, and doxicycline which can be applied in pure form, mixed with contrast or in foam form . One of the main advantages is the low cost of sclerosing agents.
Knowing the indications for use, chemical properties and clinical benefits, edges, and risks of these products are essential for a well-trained IR. This learning process will be supported in the hands-on training course featuring educational cases, interactive case-based discussions, and tips and tricks from real-life experience, allowing participants to gain the expertise IRs need in the management of liquid embolic agents.
François-Mitterrand Teaching Hospital, Dijon/FR
Dr. Romaric Loffroy, M.D., Ph.D., is a full Professor of Interventional Radiology and the Head of Department at François-Mitterrand University Hospital in Dijon. He specialises in embolisation techniques with particular interest in gastrointestinal bleeding and pelvic venous disorders, liver cancer, peripheral arterial, and venous disease. He has been at the forefront of the development of new embolisation techniques for gastrointestinal bleeding, reducing the failure rate as well as the necessity of reinterventions. In 2009, Dr. Loffroy’s keen interest in research took him to Blatimore's Johns Hopkins Hospital as a postdoctoral research fellow.
Today, Dr. Loffroy's research focuses on improving the quality of tumor imaging and the development of new IR therapies for liver cancer, deep vein thrombosis, and arterial diseases. He is one of the main European leaders in the field of embolisation with liquid agents, with a particular interest in cyanoacrylates for both experimental settings and clinical applications. Dr. Loffroy has published numerous SCI journal papers and book chapters, edited and reviewed for many academic journals, participated in several international projects, and served as an evaluation expert for organisations such as the French Society of Radiology and the High Authority of Health (HAS). He is the Past President of the French Society of Vascular and Interventional Radiology (SFICV) and the Founder/Director of the European Liquid Embolic Course (ELEC).
- Comby PO, Guillen K, Chevallier O, Lenfant M, Pellegrinelli J, Falvo N, Midulla M, Loffroy R. Endovascular Use of Cyanoacrylate-Lipiodol Mixture for Peripheral Embolization: Properties, Techniques, Pitfalls, and Applications. J Clin Med. 2021 Sep 23;10(19):4320.
- Loffroy R, Guillen K, Comby PO, Chevallier O. Prostate Artery Embolization for Benign Prostatic Hyperplasia: Rationale for the Use of N-Butyl Cyanoacrylate Glue as an Embolic Agent. Cardiovasc Intervent Radiol. 2022 Jun;45(6):824-825.
- Né R, Chevallier O, Falvo N, Facy O, Berthod PE, Galland C, Gehin S, Midulla M, Loffroy R. Embolization with ethylene vinyl alcohol copolymer (Onyx®) for peripheral hemostatic and non-hemostatic applications: a feasibility and safety study. Quant Imaging Med Surg. 2018 Apr;8(3):280-290.
- Sapoval M, Vidal V, Déan C, Del Giudice C, Tradi F, Chevallier O, Charles-Nelson A, Pellerin O, Loffroy R. Safety and Efficacy of Peripheral Embolization with EASYX Liquid Embolic Agent: A Multicenter Prospective Study. J Vasc Interv Radiol. 2021 Aug;32(8):1136-1143.
- Nevesny F, Chevallier O, Falvo N, Guillen K, Malakhia A, Pellegrinelli J, Comby PO, Bonniaud B, Midulla M, Loffroy R. Bleomycin for Percutaneous Sclerotherapy of Venous and Lymphatic Malformations: A Retrospective Study of Safety, Efficacy and Mid-Term Outcomes in 26 Patients. J Clin Med. 2021 Mar 22;10(6):1302.
- Tartaglia, F.M. Salvatori, G. Russo et al. Selective embolization of thyroid arteries for preresection or palliative treatment of large cervicomediastinal goiters. Surg Innov 2011; 18:70-78.