Non-adhesive Liquid Embolic Agent Research Articles

Endovascular Treatment of Visceral Artery Pseudoaneurysms with Ethylene-Vinyl Alcohol (EVOH) Copolymer-Based Non-Adhesive Liquid Embolic Agents (NALEAs).

Background and Objectives: Treatment of visceral artery pseudoaneurysms (VAPs) is always indicated regardless of their diameters, as their risk of rupture is significantly higher than that of visceral artery aneurysms. The invasiveness of surgery and its associated complications have led to a shift in favor of radiological interventions as the initial treatment of choice. However, there are still some unanswered questions on endovascular treatment of VAPs regarding the optimal endovascular technique and the efficacy and safety outcomes. The purpose of this multicenter study was to retrospectively evaluate the effectiveness and safety of endovascular treatment of visceral pseudoaneurysms using Ethylene-Vinyl Alcohol (EVOH) Copolymer-Based Non-Adhesive Liquid Embolic Agents (NALEAs). Materials and Methods: Consecutive patients who underwent endovascular embolization with EVOH-based NALEAs for visceral artery pseudoaneurysms between January 2018 and June 2023 were retrospectively evaluated. Results: 38 embolizations were performed. Technical success was achieved in all patients. The clinical success rate was high (92.1% overall), with no significant differences between ruptured and unruptured VAPs (p = 0.679). Seven patients (18.4%) experienced procedure-related complications, related to one case of non-target embolization, four splenic abscesses due to end-organ infarction, and two femoral pseudoaneurysms. The rates of procedure-related complications, end-organ infarction, and vascular access-site complications did not significantly differ between ruptured and unruptured VAPs (p > 0.05). Conclusions: Both ruptured and unruptured visceral pseudoaneurysms can be effectively and safely treated with NALEA-based endovascular embolization. We suggest considering the use of NALEAs, particularly in specific clinical cases that highlight their advantages, including patients with coagulopathy, fragile vessels, and embolization targets that are located at a considerable distance from the microcatheter tip and are otherwise difficult to reach.

Pulmonary Artery Pseudoaneurysms Embolization: Bicentric Experience and Review of the Literature.

The purpose of this bicentric case series was to report the safety, efficacy, and clinical outcome of transcatheter embolization in pulmonary artery pseudoaneurysms (PAPAs). Between January 2016 and June 2021, eight patients with PAPA were subjected to transcatheter embolization. The total number of patients was eight, of which five were female, with a mean age of 62 ± 14 years (average ± standard deviation). Etiology was traumatic in 2/8 cases and iatrogenic in 6/8 cases (after positioning a Swan-Ganz catheter in 5/6 cases and a temporary pacemaker in the latter case). In a single case, the PAPA was incidentally discovered during a routine X-ray, in the remaining 7 cases, the procedure was performed in emergency settings. PAPA embolization was performed using detachable coils alone in 3 cases; coils and glue in 1 case; coils, glue, and vascular plug in 1 case; coils and non-adhesive liquid embolic agents (Onyx and Squid respectively) in 2 cases; and non-adhesive liquid embolic agent alone (Onyx) in 1 case. No peri-procedural or post-procedural complications were recorded. Both the technical and clinical success rates were 100.0%. In conclusion, endovascular embolization is a technically feasible and safe therapeutic option for patients with PAPAs.

Abstract No. 38 Pivotal, Prospective Multicenter US Study of Lava, a Liquid Embolic Agent Used to Treat Peripheral Arterial Hemorrhage

The Lava Liquid Embolic System (Lava LES; BlackSwan Vascular, Inc, Hayward, CA) is an injectable, non-adhesive liquid embolic agent. A prospective, single-arm, multicenter study, Liquid Embolization of Arterial Hemorrhages in Peripheral Vasculature (LAVA), was designed to evaluate the safety and effectiveness of the Lava LES for peripheral arterial hemorrhage. Adult patients with active arterial bleeding in the peripheral vasculature were recruited at 20 centers in the USA. Of 160 screened patients, 113 patients received Lava LES (mean [SD] age, 57.4 [18.0] years; 63.7% male; most frequent morbidities hypertension 58.4%, hyperlipidemia 31.9%, renal insufficiency 28.3%, diabetes 24.8%) for 148 lesions. All patients received Lava LES at one of two viscosities (57.7% and 42.3% with lower and higher viscosity, respectively) with (33.1%) or without (66.9%) adjunctive coil and/or plug embolization. Target lesion was defined as active hemorrhage or pseudoaneurysm on computed tomography (CT) angiography, endoscopy and/or conventional angiography. The primary safety endpoint was freedom from 30-day major adverse events (MAEs; ischemia or infarction of the target territory, non-target embolization, allergic reactions to Lava LES, catheter breakage or entrapment). The primary effectiveness endpoint was clinical success (absence of bleeding from the target lesion after embolization, without the need for emergency surgery, re-embolization, or other target lesion re-interventions within 30 days). Targeted areas of bleeding included non-gastrointestinal (GI) visceral (36.3%; most frequently splenic or hepatic), renal (21.2%), upper GI (9.7%), lower GI (8.8%), extremity (7.1%), and other (16.8%). The mean (SD) volume of Lava LES delivered was 0.7 (0.7) mL. Clinical success at 30 days was 94.3% (133/141; 95% confidence interval: 89.1–97.5%). Technical success (absence of angiographic evidence of bleeding from the target lesion at the conclusion of the index procedure) was 97.3% (144/148). There were no reports of MAEs. All-cause mortality rate at 30 days was 8.3% (9/109; 4 patients exited the study without death before Day 30); two patients (1.9%) had bleeding-related mortality attributable to the target territory. Results from the LAVA study suggest that Lava LES is effective and can be safely used as an embolic agent for treatment of peripheral arterial hemorrhage.

Non-Adhesive Liquid Embolic Agents in Extra-Cranial District: State of the Art and Review of the Literature.

This review focuses on the use of “new” generation of non-adhesive liquid embolic agents (NALEA). In literature, non-adhesive liquid embolic agents have mainly been used in the cerebral district; however, multiple papers describing the use of NALEA in the extracranial district have been published recently and the aim of this review is to explore and analyze this field of application. There are a few NALEA liquids such as Onyx, Squid, and Phil currently available in the market, and they are used in the following applications: mainly arteriovenous malformations, endoleaks, visceral aneurysm or pseudoaneurysm, presurgical and hypervascular lesions embolization, and a niche of percutaneous approaches. These types of embolizing fluids can be used alone or in combination with other embolizing agents (such as coils or particles) so as to enhance its embolizing effect or improve its possible defects. The primary purpose of this paper is to evaluate the use of NALEAs, predominantly used alone, in elective embolization procedures. We did not attempt a meta-analysis due to the data heterogeneity, high number of case reports, and the lack of a consistent follow-up time period.

Iterative Metal Artifact Reduction (iMAR) of the Non-adhesive Liquid Embolic Agent Onyx in Computed Tomography

BackgroundA drawback of Onyx, one of the most used embolic agents for endovascular embolization of intracranial arteriovenous malformations (AVM), is the generation of imaging artifacts (IA) in computed tomography (CT). Since these artifacts can represent an obstacle for the detection of periprocedural bleeding, this study investigated the effect of artifact reduction by an iterative metal artifact reduction (iMAR) software in CT in a brain phantom.MethodsTwo different in vitro models with two-dimensional tube and three-dimensional AVM-like configuration were filled with Onyx 18. The models were inserted into a brain imaging phantom and images with (n = 5) and without (n = 10) an experimental hemorrhage adjacent were acquired. Afterwards, the iMAR algorithm was applied for artifact reduction. The IAs of the original and the post-processed images were graded quantitatively and qualitatively. Moreover, qualitative definition of the experimental hemorrhage was investigated.ResultsComparing the IAs of the original and the post-processed CT images, quantitative and qualitative analysis showed a lower degree of IAs in the post-processed images, i.e. quantitative analysis: 2D tube model: 23.92 ± 8.02 Hounsfield units (HU; no iMAR; mean ± standard deviation) vs. 5.93 ± 0.43 HU (with iMAR; p < 0.001); qualitative analysis: 3D AVM model: 4.93 ± 0.18 vs. 3.40 ± 0.48 (p < 0.001). Furthermore, definition of the experimental hemorrhage was better in the post-processed images of both in vitro models (2D tube model: p = 0.004; 3D AVM model: p = 0.002).ConclusionThe iMAR algorithm can significantly reduce the IAs evoked by Onyx 18 in CT. Applying iMAR could thus improve the accuracy of postprocedural CT imaging after embolization with Onyx in clinical practice.

Endovascular Treatment of Chronic Subdural Hematomas through Embolization: A Pilot Study with a Non-Adhesive Liquid Embolic Agent of Minimal Viscosity (Squid).

Objective: Endovascular embolization using non-adhesive agents (e.g., ethylene vinyl alcohol copolymer with suspended micronized tantalum dissolved in dimethyl sulfoxide; Squid, Balt Extrusion) is an established treatment of brain arteriovenous malformations, dural arteriovenous fistulas, and hypervascular neoplasms. Middle meningeal artery (MMA) embolization is a relatively new concept for treating chronic subdural hematomas (CSDH). This study aimed to evaluate the safety and effectiveness of the use of Squid in the endovascular treatment of CSDH. Methods: Embolization was offered to patients with CSDH with minimal or moderate neurological deficits and patients who had previously undergone open surgery to evacuate their CSDH without a significant effect. Distal catheterization of the MMA was followed by embolization of the hematoma capsule with Squid 12 or Squid 18. Safety endpoints were ischemic or hemorrhagic stroke and any other adverse event of the endovascular procedure. Efficacy endpoints were the feasibility of the intended procedure and a ≥ 50% reduction of the maximum depth of the CSDH confirmed by follow-up computed tomography (CT) after >3 months. Results: Between November 2019 and July 2021, 10 patients (3 female and 7 male, age range 42–89 years) were enrolled. Five patients had bilateral hematomas, and five patients had previously been operated on with no significant effect and recurrent hematoma formation. The attempted embolization was technically possible in all patients. No technical or clinical complication was encountered. During a post-procedural follow-up (median 90 days), 10 patients improved clinically. A complete resolution of the CSDH was observed in 10 patients. The clinical condition of all enrolled patients during the so-far last contact was rated mRS 0 or 1. Conclusion: A distal catheterization of the MMA for the endovascular embolization of CSDH with Squid allowed for the devascularization of the MMA and the dependent vessels of the hematoma capsule. This procedure resulted in a partial or complete resolution of the CSDH. Procedural complications were not encountered.

Imaging Artifacts of Nonadhesive Liquid Embolic Agents in Conventional and Cone-beam CT in a\xa0Novel in Vitro AVM Model

BackgroundA major drawback of liquid embolic agents (LEAs) is the generation of imaging artifacts (IA), which may represent a crucial obstacle for the detection of periprocedural hemorrhage or subsequent radiosurgery of cerebral arteriovenous malformations (AVMs). This study aimed to compare the IAs of Onyx, Squid and PHIL in a novel three-dimensional in vitro AVM model in conventional computed tomography (CT) and cone-beam CT (CBCT).MethodsTubes with different diameters were configured in a container resembling an AVM with an artificial nidus at its center. Subsequently, the AVM models were filled with Onyx 18, Squid 18, PHIL 25% or saline and inserted into an imaging phantom (n = 10/LEA). Afterwards CT and CBCT scans were acquired. The degree of IAs was graded quantitatively (Hounsfield units in a defined region of interest) and qualitatively (feasibility of defining the nidus)—Onyx vs. Squid vs. PHIL vs. saline, respectively.ResultsQuantitative density evaluation demonstrated more artifacts for Onyx compared to Squid and PHIL, e.g. 48.15 ± 14.32 HU for Onyx vs. 7.56 ± 1.34 HU for PHIL in CT (p < 0.001) and 41.88 ± 7.22 density units (DU) for Squid vs. 35.22 ± 5.84 DU for PHIL in CBCT (p = 0.044). Qualitative analysis showed less artifacts for PHIL compared to Onyx and Squid in both imaging modalities while there was no difference between Onyx and Squid regarding the definition of the nidus (p > 0.999).ConclusionIn this novel three-dimensional in vitro AVM model, IAs were higher for the EVOH/tantalum-based LEAs Onyx and Squid compared to iodine-based PHIL. Onyx induced the highest degree of IAs with only minor differences to Squid.

Management of Renal Cell Carcinoma With Extensive Caval Thrombosis Utilizing a Temporary Atrial Caval Filter Through a Combined Endovascular and Open Surgical Technique

The most common cause of neoplastic thrombotic infiltration of the inferior vena cava is renal cell carcinoma (RCC). In the present report we described a case of a patient with massive RCC and extensive neoplastic thrombosis reaching the retrohepatic tract of the inferior vena cava. After a discussion in a multidisciplinary team meeting we decided to perform a radical nephrectomy with vena cava thrombectomy along with the support of a novel removable vena cava filter in order to avoid thromboembolism during the surgical procedure. Furthermore, a preoperative renal artery embolization with a non-adhesive liquid embolic agent was performed ahead of the surgical procedure in order to reduce the risk of intraoperative bleeding. The surgical procedure performed the day after was based on a hybrid endovascular-surgical approach consisting in nephrectomy, liver derotation, cavotomy with the additional use of a novel temporary caval filter, thus reducing the risk of intraoperative thromboembolic dissemination.

Experience of intracranial arteriovenous malformations endovascular treatment with advanced techniques and non-adhesive liquid embolic agents using

Objective ‒ to evaluate the possibility of endovascular embolization using non-adhesion of liquid embolic agents as monotherapy for the treatment of cerebral arteriovenous malformations (AVM), its reliability and safety.Materials and methods. examination and gradual endovascular treatment of 64 patients (120 sessions) using non-adhesive liquid embolic agents. Patients were divided into two groups: with ruptured AVM (n = 43) and with unruptured (n = 21). In all cases of unruptured AVM, signs indicating an increased risk of rupture of the AVM were verified.Results. the average decrease in volume after embolization was 79.5 % (up to 50 % ‒ in 7 cases, 50‒75 % ‒ in 14, 75‒99 % ‒ in 29). Complete exclusion of AVM was achieved in 14 (22 %) patients. On average, 2–3 feeders were embolized on the AVM to achieve such results. It was found that the number of feeders was directly proportional to the number of sessions required. Malformations of small size (up to 3 cm) often managed to close in one session. Clinically significant deficiency (2 on the modified Rankin scale) after embolization was found in 2 (3 %) patients. The deficit regressed within 7 days. The angiographic frequency of complete obliteration of AVM at the end of all embolization procedures was 22 % (14 AVM).Conclusions. knowledge of the angioarchitectural characteristics of AVM, which are suitable for the treatment with liquid embolic agents, and their careful selection allow to achieve a high frequency of occlusion with a low frequency of complications. The use of superselective intranidal or perinidal positions of the catheter, slow controlled injections that protect the draining veins, the gradual embolization make the therapy safer.

Emergency tips recanalisation and gastroesophageal varices embolisation with an ethylene vinyl alcohol copolymer agent (Squid) and detachable coils

Transjugular intrahepatic portosystemic shunt (TIPS) is currently indicated as first therapeutic option in the main complications of portal hypertension, including bleeding gastroesophageal varices and refractory ascites. In case of bleeding gastroesophageal varices, an adjuvant embolisation within TIPS can be useful to prevent rebleeding. In the present technical note, the management in emergency of a patient with haemorrhagic shock due to bleeding gastroesophageal varices and occluded TIPS is reported. TIPS recanalisation with an adjunctive stent and high-pressure balloon angioplasty and gastroesophageal varices embolisation using detachable coils and a non-adhesive liquid embolic agent were performed during the same emergent procedure. After the procedure, clinical stabilisation of the patient was achieved, with blood transfusions suspension and Blakemore tube removal. At 6 months, regular TIPS patency at colour Doppler and no rebleeding episodes were recorded. To our knowledge, whilst coils are routinely used for varices embolisation, non-adhesive liquid embolic agents have been never mentioned. Liquid embolic agents seem to provide a stable plug strengthening the embolising action of the coils. Further studies involving a cohort of patients with long-term follow-up will be necessary to confirm whether this association can be more effective than coils alone in gastroesophageal varices embolisation.

INCIDENTAL FINDING OF ONYX EMBOLIZATION OF THE PULMONARY ARTERY: A RARE COMPLICATION OF HIGH FLOW DURAL ARTERIOVENOUS FISTULA REPAIR

SESSION TITLE: Medical Student/Resident Imaging Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: October 18-21, 2020 INTRODUCTION: Onyx® is a non-adhesive liquid embolic agent used for embolization of brain arteriovenous malformations (bAVMs). We present a case of a 58 year-old woman with shortness of breath found to have a foreign body on chest imaging later determined to be a pulmonary artery Onyx embolus. CASE PRESENTATION: A 58 year-old woman with history of tracheostomy-dependent chronic respiratory failure and dural arteriovenous fistula (DAVF) status post multistage embolic repair presented to the emergency department with shortness of breath, chest tightness, and productive cough for one week. On arrival, she was hypoxic requiring 4L oxygen via tracheostomy mask to maintain an oxygen saturation of 94%. Her exam was remarkable for expiratory wheezes in all lung fields and purulent secretions from her tracheostomy. Chest radiograph revealed a linear radiopaque foreign body overlying the expected location of the right pulmonary artery. A computed tomography of the chest confirmed the finding of a tortuous metallic foreign body within the lower lobe branches of the right pulmonary artery. No lung parenchymal changes were noted in the area supplied by these vessels. Interventional radiology reviewed these images and determined the foreign body to be an irretrievable embolus of the agent used during her DAVF repair, her final treatment having occurred three months prior. This finding was of no significance to the patient’s presentation. She was diagnosed with viral tracheitis and managed symptomatically with complete resolution of symptoms. DISCUSSION: The Onyx liquid embolic agent is made of ethylene vinyl alcohol copolymer dissolved in dimethyl sulfoxide and suspended micronized tantalum powder to make it radio-opaque. It is designed to harden within five minutes of deployment and available in two different formulations varying in viscosity. The lower viscosity Onyx 18 will travel further from the deployment catheter compared to the higher viscosity Onyx 34. Its non-adhesive nature and ease of use makes it a preferable choice to the cyanoacrylate-based (“glue”) agents for some neurointerventionalists. Common complications include hemorrhage, stroke and vessel perforation. Embolus migration has been rarely reported. It is usually noted incidentally on follow-up imaging, as happened with our patient. Clinical presentations are typically asymptomatic, though there have been reports of acute presentations of hypoxemia and superior vena cava syndrome. Treatment options include conservative measures, retrieval of embolus or medical management of symptoms. CONCLUSIONS: Brain AVMs are increasingly being treated with Onyx embolization. Distal migration to non-targeted vessels can be a complication of this procedure, which may be discovered as a puzzling incidental or less commonly an acute finding. Reference #1: FDA, Access Data - Onyx Liquid Embolic system, Instructions for Use, 2003, Site: https://www.accessdata.fda.gov/cdrh_docs/pdf3/P030004c.pdf Reference #2: Tolly, B. T., Kosky, J. L., Koht, A., & Hemmer, L. B. (2016, August 31). A Case Report of Onyx Pulmonary Arterial Embolism... : A&A Practice. LWW. https://journals.lww.com/aacr/fulltext/2017/02150/A_Case_Report_of_Onyx_Pulmonary_Arterial_Embolism.7.aspx#JCL-P-13 Reference #3: Crusio, R., Ramachandran, K., Ramachandran, K., Kupfer, Y., & Tessler, S. (2011). Superior vena cava syndrome caused by embolisation of liquid Onyx. BMJ case reports, 2011, bcr1120103502. https://doi.org/10.1136/bcr.11.2010.3502 DISCLOSURES: No relevant relationships by Timothy Miett, source=Web Response No relevant relationships by Nishka Shetty, source=Web Response

Intermixed Dimethyl-Sulfoxide–Based Nonadhesive Liquid Embolic Agents Delivered Serially via the Same Microcatheter for Cerebral AVM Treatment

Conventional nonadhesive liquid embolic agents currently are the criterion standard for endovascular embolization of cerebral AVMs. However, inadequate distal penetration into the nidus and unstable proximal plug formation are the major limitations of this approach and of the currently available embolic materials. The aim of this study was to evaluate the hypothetic efficacy of combining liquid embolic agents with different properties and viscosities for use in endovascular embolization of cerebral AVMs. From March 2018 to March 2019, sixteen patients with cerebral AVMs (12 women, 4 men; age range, 33-61 years) underwent endovascular embolization with combined liquid embolic agents delivered serially via a single microcatheter. The procedure consists of initial embolization with PHIL 30%, followed by Menox 18 through the same microcatheter. According to the Spetzler-Martin scale, 11 (68.75%) AVMs were grades I-II, 4 (25%) were grade III, and 1 (6.25%) was grade IV. Angiographic, technical, and clinical outcomes were analyzed independently. Combined PHIL and Menox embolization through the same microcatheter via 21 pedicles was performed in these 16 patients. Once the length of the reflux reached approximately 2 cm, PHIL 30% was switched to Menox 18. Antegrade flow and distal penetration of the serially applied liquid embolic agents were observed in all 16 cases. The ability to completely control the flow of the materials and avoid any dangerous proximal reflux was noted in all performed embolizations. The estimated average size reduction of the treated AVMs was 85%, ranging from 50% to 100%. Complete embolization was achieved in 10/16 or 62.5% of the cases. There was no procedure-related complication during or after the embolization. No mortality or postprocedural clinical worsening was seen. Clinical success and complete obliteration were confirmed with at least 1 follow-up angiography in 10/16 patients. Serial delivery of nonadhesive liquid embolic agents via the same microcatheter was safe and effective in our study and may be a potential technique for routine AVM treatment. However, further investigations are required to validate the safety and the efficacy of the method.

신경혈관 중재술에서의 신경계감시의 역할: 척추 동정맥 기형의 증례

Endovascular embolization is one of the treatment options for spinal arteriovenous malformation (AVM). Intraoperative neurophysiological monitoring (IONM) is widely used in procedures where post-procedure neurological deterioration may occur. 24-year-old man, previously diagnosed with spinal AVM, visited a tertiary hospital complaining of weakness and tingling sensation on both lower extremities. After confirming the right 6th thoracic segmental artery as the target point of the AVM feeder, an endovascular procedure was performed with IONM. During embolization using a nonadhesive liquid embolic agent (Onyx^®), the amplitude of motor evoked potentials of the bilateral tibialis anterior and right abductor hallucis brevis were decreased over the alarm criteria. After the procedure, the patient developed weakness in both legs, hypoesthesia, and neurogenic bladder. After 4 weeks of rehabilitation, motor and bladder function partially improved. This case presentation is to emphasize the role of the continuous multimodality IONM in making important decisions during neuroendovascular procedures.

Outcomes After Onyx Embolization as Primary Treatment for Cranial Dural Arteriovenous Fistula in the Past Decade

This retrospective single-center study aims to evaluate endovascular therapy (EVT) of cranial dural arteriovenous fistulas (dAVF) with ethylene vinyl alcohol (EVOH) copolymer (Onyx) regarding occlusion rates, complications, and recurrences. From January 2008 to April 2018, 75 patients with dAVF (41 men, 34 women; mean age 56 years) underwent EVT with the nonadhesive liquid embolic agent as primary treatment. Patient records and angiograms were reviewed for demographic data, symptoms, fistula type and size, number of EVTs, amount of embolic material, occlusion rates, and recurrences. Seventy-five patients with dAVFs were primarily embolized with EVOH in 96 EVTs. According to the Merland-Cognard classification the majority of dAVFs treated were type 4 (42.7%), followed by type 2a (18.7%), type 2a+b (17.3%), type 1 (8%), type 2b (5.3%), type 3 (5.3%), and type 5 (2.7%). Complete occlusion (CO) of the dAVF was achieved in 45/75 (60%) of cases after a single EVT and in 58 (77%) patients after one or several EVTs. Seven patients (9%) required additional surgical therapy for CO. Successful treatment was achieved for 70/75 (93%) patients including 10 (13%) patients with residual dAVFs type 1-2a. Recurrence after CO occurred in one (1.3%) patient and four (5.3%) patients remained refractory to therapy with dAVFs type > 2a. Procedure-related permanent morbidity occurred in 4/75 (5.3%) patients. For more than a decade transarterial EVOH embolization has established as the first-line treatment for cranial dAVFs with high cure rates and low rates of complications and recurrences. Additional neurosurgical therapy is rarely required for curative treatment.

Combined treatment approach to cerebral arteriovenous malformation in pediatric patients: stereotactic radiosurgery to partially Onyx-embolized AVM.

Treatment of cerebral arteriovenous malformations (AVM)-the most common cause of stroke in the pediatric population-can be challenging due to the complexity of size, morphology, and location. There is a significant risk in comparison to AVM treatment among adults. Thus, AVM treatment in the pediatric population imposes unique challenges. Recent improvements include optimized catheter techniques and better embolization materials, such as Onyx, a non-adhesive liquid embolic agent used in the adult population. These improvements have increased the success rate of total and near-total obliteration of cerebral AVM. However, the use of Onyx causes significant distortion of the MR and CT images, which must be accounted for in any radiation treatment planning predicated on CT and MRI. These image distortions impact on the actual delivered dose to the nidus and behoove heterogeneity correction. Our group has previously shared a solution for heterogeneity correction in the adult population. The purpose of this study is to show our experience in this unique group of pediatric patients. This is a retrospective review of pediatric patients, who were undergoing combined endovascular embolization followed by SRS. The cohort consists of 14 patients undergoing SRS treatment in our institute between November 2006 and December 2012 with a mean follow-up of 49.9months. Within this cohort, we retrospectively reviewed 12 consecutive pediatric patients who underwent a combined endovascular and SRS approach with a mean follow-up of 52.1months and two patients receiving SRS-only treatment were excluded. In our cohort of 14 patients, 7 (50%) were male, with a mean age of 17.3years (12.0-22.9) at the time of radiosurgery treatment. Mean age of beginning the combined modality treatment was 15.3years (8.4-20). The median time from diagnosis to SRS was 24.3months (11.1-64.4months) in the complete cohort and 25.6months (11.1-64.4) in the multimodality group. The overall median follow-up period was 49.9months (range 12.8-118.8months) in the complete cohort and 52.1months (range 12.8-118.8months) in the multimodality group. Eleven (78.6%) patients had at least one episode of hemorrhage prior to treatment. Spezler-Martin grades at baseline ranged from 2 to 5 (mean 3.2). Fifty percent had grade IV and V. Patients underwent a median of 2 (range 1-5) embolization procedures. The radiosurgical treatment dose to the margin of the angiography-based nidus: median prescription dose of 21.49Gy (14.39-27.51) with a median max dose of 27.77Gy (18.93-32.52). The median treatment volume was 0.6cm3 (0.1-7.3cm3). The Onyx embolization reduced the nidus target volume by a median of 66.7% (12.0-92.7%). We confirmed 10/14 (71%) complete closures. In 2/14 (14.2%) additional patients, a significant flow reduction was noted. In 1/14 (7.1%) patients, no significant change was noted during the observation period and two (14.2%) patients were without follow-up information. In two patients, post-treatment edema was noted; however, none was clinically significant and resolved without additional intervention or treatment. This cohort comprises the largest combined Onyx-SRS pediatric experience in the literature. In conjunction with our adult group study, we show that the use of Onyx reduces the SRS treatment target volume significantly. Importantly, we implemented the heterogeneity correction to avoid increased radiation exposure to normal surrounding brain tissue. The combined approach appears to be safe provided that the above-mentioned corrections are implemented.

Embolization of Intracranial Dural Arteriovenous Fistulas Using PHIL Liquid Embolic Agent in 26 Patients: A Multicenter Study.

The introduction of liquid embolic agents has revolutionized endovascular approach to cranial vascular malformations. The aim of the study was to retrospectively assess the efficacy and safety of Precipitating Hydrophobic Injectable Liquid (PHIL), a new nonadhesive liquid embolic agent, in the treatment of patients with cranial dural arteriovenous fistulas. The primary end point was the rate of complete occlusion of dural arteriovenous fistulas. Secondary end points included the incidence of adverse events and clinical status at 3-month follow-up. This was a retrospective multicenter study. Twenty-six consecutive patients with dural arteriovenous fistulas (de novo or previously treated) treated by injection of PHIL only or with PHIL in combination with other embolization products (such as Onyx or detachable coils) were included in the study. Recruitment started in August 2014 and ended in September 2015. Twenty-two (85%) patients were treated with PHIL only, with 3 patients treated with both PHIL and Onyx, and 1, with both PHIL and coils. Immediate complete angiographic occlusion was achieved in 20 (77%) patients. Of the 6 patients with residual fistulas, 3 were retreated with PHIL and 1 achieved angiographic cure. An adverse event was seen in 1 patient who developed worsening of preexisting ataxia due to acute thrombosis of the draining vein. PHIL appears to be safe and effective for endovascular treatment of cranial dural arteriovenous fistulas. Short-term angiographic and clinical results are comparable with those of Onyx, with the added advantage of easier preparation and improved homogeneous cast visualization. The use of iodine as a radio-opacifier also produces considerably less artifacts on CT compared with tantalum-based embolic materials.

Percutaneous Phil™-Embolization for Preoperative Therapy of Carotid Body Paragangliomas

Introduction: Paragangliomas are rare tumors representing a therapeutic challenge. In particular, the surgical removal may lead to life-threatening bleeding. The preoperative percutaneous embolization is an alternative that allows a high closure rate of tumor-feeding vessels in a short intervention time and thus significantly reduces intraoperative bleeding probability. Complete tumor resection is facilitated thereby. The use of a new non-adhesive liquid embolic agent is presented here. Methods: A 50-year old patient presented with 4 cm large paraganglioma of the carotid body (Shamblin II). A percutaneous embolization with 7 ml PHIL™ (injectable precipitating hydrophobic liquid) was performed preoperatively. 24 h later the complete surgical resection of the tumor was performed. Results: A good distribution of the liquid embolic agent could be achieved over the entire tumor. Intraoperative resection of the tumor was much easier and faster due to low bleeding tendency over the entire surface of the tumor. Total blood loss was less than 50 ml. All adjacent nerve and arterial structures could be spared. Postoperative nerve function was normal and the patient was discharged on the 4th postoperative day. Conclusion: The combination of percutaneous embolization and surgical resection provides a safe combination in the treatment of advanced carotid body paragangliomas. The use of a novel liquid embolic agent may possibly further optimize the therapy.

Embolisation of high flow extracranial/peripheral arteriovenous malformations (AVMs) with ethylene vinyl alcohol copolymer (ONYX®) in children—Birmingham Children’s Hospital experience

Background ONYX® is a non-adhesive liquid embolic agent, ethylene vinyl alcohol copolymer dissolved in various concentration of dimethyl sulfoxide. Onyx has been used for endovascular treatment of cerebral vascular malformation. In our series, we present our experience in seven paediatric patients with peripheral high-flow arteriovenous malformations (AVMs) treated with Onyx.

E-061 Onyx Embolisation Through the Scepter Dual-Lumen System: Mechanisms and Utility

IntroductionEthyl Vinyl Alcohol co-polymer Onyx (ev3 Inc., Irvine, CA) is a non-adhesive but cohesive liquid embolic agent that can be used to occlude vascular lesions. On label indications are for...

E-029 Balloon-augmented target vessel sacrifice with liquid embolic agents

IntroductionVessel sacrifice remains a valuable tool in the treatment of select vascular lesions. Conventionally, neurointerventionalists have relied on coil embolization as their primary means of vessel sacrifice since detachable balloons...