Preliminary experience with the liquid embolic material agent PHIL (Precipitating Hydrophobic Injectable Liquid) in treating cranial and spinal dural arteriovenous fistulas: technical note

Endovascular treatment of epidural arteriovenous fistula associated with sacral arteriovenous malformation: case report

Spinal epidural arteriovenous fistulas with sacral arteriovenous malformation (AVM) are a rare type of spinal arteriovenous fistulas. There are two varieties of spinal epidural arteriovenous fistulas (SEDAVFs), with type 1 involving intradural venous drainage and type 2 not involving intradural venous drainage. We present a case of transarterial embolization for type 1 SEDAVFs with sacral AVM. Within 8 months, a 14-year-old boy presented with progressively weaker lower extremities and bladder-bowel dysfunction. Magnetic resonance imaging (MRI) of the whole spine revealed thoracic spinal cord congestion, a single dilated flow void running from the lumbosacral area to the conus medullaris, and continuing cranial draining up to the C5 level via the perimedullary vein. Filling of the venous sac through a preferential feeder after embolizing the AVM nidus was performed. After 3 months, the clinical follow-up showed improvement of motoric function, although mild. Endovascular treatment for SEDAVF type 1 might have achieved total obliteration without any procedural complications. Nevertheless, it can be very challenging due to multiple feeders and the presence of an AVM nidus like in this case. However, the most difficult thing in fistula cases is establishing the diagnosis and finding the fistula point. Early treatment is required, due to the fact that longstanding lesions could cause irreversible damage.

Endovascular treatment for sphenoidal region dural arteriovenous fistula

Sphenoidal region dural arteriovenous fistulas (DAVFs) are rare. Endovascular treatment (EVT) is an effective treatment approach. However, understanding and performing EVT for sphenoidal region DAVFs are difficult and challenging. Therefore, we performed a review to explore this issue further. In this review, we discuss the dural feeders and venous structures of the sphenoidal region, the angioarchitecture of sphenoidal region DAVFs, the role and principle of EVT, various EVT techniques, and the prognosis and complications associated with EVT. We found that various EVT techniques, including transarterial embolization (TAE), retrograde transvenous embolization (TVE), and direct puncture EVT, can be used to treat sphenoidal region DAVFs. TAE represents the most commonly utilized approach. TVE and direct puncture EVT should be limited to highly selective cases. EVT must penetrate the fistula and very proximal venous recipient pouch with a liquid embolic agent or coil the fistula point to have a complete curative effect. Successful EVT can lead to the obliteration of sphenoidal region DAVFs and a good clinical outcome. However, these complications cannot be neglected.

Complex torcular dural arteriovenous fistula leading to cortical venous reflux-induced severe varix and subsequent bilateral cerebral hemispheric hemorrhage: a case report

Background and importance

Dural arteriovenous fistulas (dAVFs) with cortical venous reflux (CVR) are associated with a higher incidence of intracranial hemorrhage (ICH). We report a rare case of a complex torcular dAVF with severe cortical veins (CV) varix leading to extensive bilateral cerebral hemorrhages. This discovery suggests a potential new subtype of dAVF. The case underscores the necessity of a comprehensive understanding of hemodynamic changes in dAVFs and the importance of considering venous compensatory capacity in treatment. This case challenges existing classifications and treatment strategies for dAVFs, highlighting the need for further research and discussion within the neurosurgical community.

Clinical presentation

A 56-year-old male was admitted to the hospital presenting with dizziness, fatigue, and numbness. Brain CT scans revealed extensive bilateral cerebral hemorrhages. Digital subtraction angiography (DSA) identified a complex torcular dAVF. No cerebral sinus venous thrombosis was detected, but a venous variation in the left transverse sinus was observed. Preoperative DSA demonstrated the patient's well-developed venous compensatory ability. Subsequently, the patient underwent transarterial embolization. The patient made a good recovery. Follow-up DSA and MR angiography at 3 months and 1 year post-treatment showed no recurrence.

Conclusion

DAVFs are rare lesions, prone to ICH, particularly when CVR is involved. We report a rare case of CVR with severe varix leading to hemorrhagic lesions in both cerebral hemispheres. Our aim is to alert neurosurgical colleagues worldwide to this potential new subtype and to evaluate treatment options, in order to assist those who may encounter such cases in the future.

Progress of tissue adhesives based on proteins and synthetic polymers

In recent years, polymer-based tissue adhesives (TAs) have been developed as an alternative to sutures to close and seal incisions or wounds owing to their ease of use, rapid application time, low cost, and minimal tissue damage. Although significant research is being conducted to develop new TAs with improved performances using different strategies, the applications of TAs are limited by several factors, such as weak adhesion strength and poor mechanical properties. Therefore, the next-generation advanced TAs with biomimetic and multifunctional properties should be developed. Herein, we review the requirements, adhesive performances, characteristics, adhesive mechanisms, applications, commercial products, and advantages and disadvantages of proteins- and synthetic polymer-based TAs. Furthermore, future perspectives in the field of TA-based research have been discussed.

Liquid Embolic Agents for Endovascular Embolization: A Review

Endovascular embolization (EE) has been used for the treatment of blood vessel abnormalities, including aneurysms, AVMs, tumors, etc. The aim of this process is to occlude the affected vessel using biocompatible embolic agents. Two types of embolic agents, solid and liquid, are used for endovascular embolization. Liquid embolic agents are usually injectable and delivered into the vascular malformation sites using a catheter guided by X-ray imaging (i.e., angiography). After injection, the liquid embolic agent transforms into a solid implant in situ based on a variety of mechanisms, including polymerization, precipitation, and cross-linking, through ionic or thermal process. Until now, several polymers have been designed successfully for the development of liquid embolic agents. Both natural and synthetic polymers have been used for this purpose. In this review, we discuss embolization procedures with liquid embolic agents in different clinical applications, as well as in pre-clinical research studies.

Novel use of precipitating hydrophobic injectable liquid (PHIL) in pre-operative angioembolisation of a large posterior auricular arteriovenous malformation

BACKGROUND

Large arteriovenous malformations are often managed via endovascular embolisation followed by surgical resection. We describe the use of a new liquid embolic agent (LEA) - precipitating hydrophobic injectable liquid (PHIL) and its advantages over existing LEAs.

CASE

A 60-year-old male presented with a progressively enlarging right post-auricular arteriovenous malformation. He underwent successive angioembolisation with PHIL and subsequent surgical resection on post-embolisation day 1.

CONCLUSION

To our knowledge, this is the first reported case of PHIL being used in pre-operative embolization of a large extra-cranial head and neck AVM. Its excellent penetration into small calibre vessels, decreased glare artefact on imaging and decreased skin pigmentation render it a compelling alternative to existing LEAs.

Surgical management of auricular arteriovenous malformations: A literature review

Auricular arteriovenous malformations (AVMs) can cause a variety of symptoms that seriously impact the patient's appearance, life, and mental well‐being. Surgery is the primary management method for auricular AVMs, but there is no consensus on how to surgically manage auricular AVMs. In this article, we document a comprehensive review of the characteristics, classification, and surgical interventions to treat auricular AVMs.

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.

Glue, Onyx, Squid or PHIL? Liquid Embolic Agents for the Embolization of Cerebral Arteriovenous Malformations and Dural Arteriovenous Fistulas

Background

Endovascular embolization is an effective treatment option for cerebral arteriovenous malformations (AVMs) and dural arteriovenous fistulas (DAVFs). A variety of liquid embolic agents have been and are currently used for embolization of AVMs and DAVFs. Knowledge of the special properties of the agent which is used is crucial for an effective and safe embolization procedure.

Material and Methods

This article describes the properties and indications of the liquid embolic agents which are currently available: cyanoacrylates (also called glues), and the copolymers Onyx, Squid and PHIL, as well as their respective subtypes.

Results

Cyanoacrylates were the predominantly used agents in the 1980s and 1990s. They are currently still used in specific situations, for example for the occlusion of macro-shunts, for the pressure cooker technique or in cases in which microcatheters are used that are not compatible with dimethyl-sulfoxide. The first broadly used copolymer-based embolic agent Onyx benefits from a large amount of available experience and data, which demonstrated its safety and efficacy in the treatment of cerebral vascular malformations, while its drawbacks include temporary loss of visibility during longer injections and artifacts in cross-sectional imaging. The more recently introduced agents Squid and PHIL aim to overcome these shortcomings and to improve the success rate of endovascular embolization. Novelties of these newer agents with potential advantages include extra-low viscosity versions, more stable visibility, and a lower degree of imaging artifacts.

Conclusion

All the available liquid embolic agents feature specific potential advantages and disadvantages over each other. The choice of the most appropriate embolic agent must be made based on the specific material characteristics of the agent, related to the specific anatomical characteristics of the target pathology.

Use of Phil Embolic Agent for Bleeding in Non-Neurological Interventions

Objective: To evaluate the safety and efficacy of the Phil liquid embolic agent in non-neurological embolization procedures. M&M: Thirty-five patients with a mean age of 62.5 years underwent percutaneous embolization using Phil for the treatment of visceral arterial bleedings in 20/35 patients (including three gluteal, one bladder, two superior mesenteric, three epigastric, one deep femoral, five internal iliac, four intercostal, and one lingual arteries), splanchnic pseudoaneurysms in 11/35 patients (including three hepatic, five splenic, and three renal arteries), pancreatic bleeding metastasis in 1/35 patient, and gastric bleeding varices in 3/35 patients. Phil is composed of a non-adhesive copolymer dissolved in DMSO (Anhydrous Dimethyl Sulfoxide) with different viscosity. Procedures were performed slowly under continuous fluoroscopic guidance to avoid embolization of non-target vessels. Results: Clinical success was obtained with a single intervention in 34 cases (97.15%), while a repeated procedure was required in one case (2.85%). No technical complications nor non-target embolization occurred. A case of post-embolic syndrome was noted (2.85%) in one patient. DMSO administration-related pain was successfully controlled by medical therapy. Conclusion: Phil can be considered a safe and effective embolic agent for the treatment of non-neurologic bleeding.

Introducing PHIL (precipitating hydrophobic injectable liquid) - a new embolic agent for the body interventional radiologist

A number of embolic agents are currently available each with their own properties. Precipitating hydrophobic injectable liquid (PHIL) is a new dimethyl sulfoxide (DMSO) compatible embolic agent with a number of specific properties which make it of interest to interventional radiologists. We review the use of PHIL in a non-neurointerventional setting, describing its use in a range of procedures such as trauma embolization, pseudoaneurysm embolization, and tumor embolization. PHIL's properties include a lack of skin discoloration, the possibility of rapid injection and a lack of glare artifact on follow-up computed tomography imaging. These properties make it an important new tool in the armamentarium of the body interventional radiologist.

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

RATIONALE AND OBJECTIVES

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.

MATERIAL AND METHODS

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.

RESULTS

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.

CONCLUSION

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.

Transarterial embolization of the external carotid artery in the treatment of life-threatening haemorrhage following blunt maxillofacial trauma

Background

Severe bleeding after blunt maxillofacial trauma is a rare but life-threatening event. Non-responders to conventional treatment options with surgically inaccessible bleeding points can be treated by transarterial embolization (TAE) of the external carotid artery (ECA) or its branches. Case series on such embolizations are small; considering the relatively high incidence of maxillofacial trauma, the ECA TAE procedure has been hypothesized either underused or underreported. In addition, the literature on the ECA TAE using novel non-adhesive liquid embolization agents is remarkably scarce.

Patients and methods

PubMed review was performed to identify the ECA TAE literature in the context of blunt maxillofacial trauma. If available, the location of the ECA injury, the location of embolization, the chosen embolization agent, and efficacy and safety of the TAE were noted for each case. Survival prognostic factors were also reviewed. Additionally, we present an illustrative TAE case using a precipitating hydrophobic injectable liquid (PHIL) to safely and effectively control a massive bleeding originating bilaterally in the ECA territories.

Results and conclusions

Based on a review of 205 cases, the efficacy of TAE was 79.4–100%, while the rate of major complications was about 2–4%. Successful TAE haemostasis, Glasgow Coma Scale score ≥ 8 at presentation, injury severity score ≤ 32, shock index ≤ 1.1 before TAE and ≤ 0.8 after TAE were significantly correlated with higher survival rate. PHIL allowed for fast yet punctilious application, thus saving invaluable time in life-threatening situations while simultaneously diminishing the possibility of inadvertent injection into the ECA-internal carotid artery (ICA) anastomoses.

The recent progress of tissue adhesives in design strategies, adhesive mechanism and applications

Tissue adhesives have emerged as an effective method for wound closure and hemostasis in recent decades, due to their ability to bond tissues together, preventing separation from one tissue to another. However, existing tissue adhesives still have several limitations. Tremendous efforts have been invested into developing new tissue adhesives by improving upon existing adhesives through different strategies. Therefore, highlighting and analyzing these design strategies are essential for developing the next generation of advanced adhesives. To this end, we reviewed the available strategies for modifying traditional adhesives (including cyanoacrylate glues, fibrin sealants and BioGlue), as well as design of emerging adhesives (including gelatin sealants, methacrylated sealants and bioinspired adhesives), focusing on their structures, adhesive mechanisms, advantages, limitations, and current applications. The bioinspired adhesives have numerous advantages over traditional adhesives, which will be a wise direction for achieving tissue adhesives with superior properties.

Updates in the management of cranial dural arteriovenous fistula

Dural arteriovenous fistula (dAVF) accounts for approximately 10% of all intracranial vascular malformations. While they can be benign lesions, the presence of retrograde venous drainage and cortical venous reflux makes the natural course of these lesions aggressive high risk of haemorrhage, neurological injury and mortality. Endovascular treatment is often the first line of treatment for dAVF. Both transarterial and transvenous approaches are used to cure dAVF. The selection of treatment approach depends on the angioarchitecture of the dAVF, the location, the direction of venous flow. Surgery and, to a lesser extent, stereotactic radiosurgery are used when endovascular approaches are impossible or unsuccessful.

Endovascular embolization of canine hepatic arteriovenous malformations using precipitating hydrophobic injectable liquid (PHIL) liquid embolic agent: a proof of concept study

Background

Hepatic arteriovenous malformations (HAVMs) are rare congenital lesions consisting of multiple high-pressure arteries feeding into low-pressure veins via a central nidus. Massive haemorrhage, portal hypertension and hepatic insufficiency can ensue. Endovascular embolization is increasingly a first line treatment method although there is no general consensus or guidelines on the most effective embolic agent or approach. We describe the novel treatment of two dogs with congenital hepatic AVMs using a modified version of the ‘pressure cooker’ technique often utilised in neurointervention with the DMSO-based PHIL embolic agent delivered via the DMSO compatible Scepter-XC dual lumen balloon catheter.

Case presentation

Two paediatric dogs were diagnosed with hepatic AVMs. Both dogs presented with ascites and abnormal liver function tests. CT angiograms revealed hepatic arterio-portal malformations arising from an enlarged celiac artery. Selective catheterisation of the artery supplying the AVM was achieved via a femoral artery approach. A Scepter XC dual-lumen compliant balloon microcatheter and Traxcess 0.014 guidewire combination was advanced to the nidus via through the 5Fr guide catheter towards the nidus. Inflation of the balloon occluded arterial inflow and PHIL was injected under continuous fluoroscopic screening until the PHIL embolic agent penetrated into the draining portal vein beyond the nidus.

In patient 1, normal portal venous waveform was restored with reversal of severe hepatic insufficiency. Whilst there was initial improvement post-operatively in patient 2 with normalisation of portal vein pressures and flow, opening of collateral nidus vessels re-established the high-pressure communication, and euthanasia was elected by the owner.

Conclusions

The ‘pressure cooker’ technique is a safe and efficacious approach to the treatment of canine HAVMs. The novel use of PHIL and the Scepter XC balloon catheter has several advantages over conventional endovascular approaches. Translational application to human paediatric interventions for similar conditions where embolic and contrast agent volume constraints are similar can be considered.

Advances in Biomaterials and Technologies for Vascular Embolization

Minimally invasive transcatheter embolization is a common nonsurgical procedure in interventional radiology used for the deliberate occlusion of blood vessels for the treatment of diseased or injured vasculature. A wide variety of embolic agents including metallic coils, calibrated microspheres, and liquids are available for clinical practice. Additionally, advances in biomaterials, such as shape-memory foams, biodegradable polymers, and in situ gelling solutions have led to the development of novel preclinical embolic agents. The aim here is to provide a comprehensive overview of current and emerging technologies in endovascular embolization with respect to devices, materials, mechanisms, and design guidelines. Limitations and challenges in embolic materials are also discussed to promote advancement in the field.

Precipitating hydrophobic injectable liquid (PHIL) embolic for the treatment of a uterine arteriovenous malformation: a technical report

OBJECTIVE

Uterine arteriovenous malformations (AVM) are unusual causes of vaginal bleeding. Although hysterectomy is the definitive treatment; uterine artery embolization (UAE) provides an alternative therapeutic option. This case presents a technical report of a uterine AVM treated successfully with transcatheter UAE using precipitating hydrophobic injectable liquid (PHIL) embolic agent.

CASE REPORT

A 41-year-old female, gravida 6, para 4, miscarriage 2, including a molar pregnancy 15 years prior, presented with massive per vaginal bleeding. Pelvic ultrasound demonstrated an acquired AVM as the underlying aetiology for her presentation. The patient underwent bilateral uterine arterial embolization. Four weeks later, there was nearly complete resolution of the AVM and the patient's menstrual cycle was restored 8 weeks after the procedure.

CONCLUSION

Uterine AVM can be treated safely and effectively with UAE using PHIL.

Precipitating hydrophobic injectable liquid embolization of intracranial vascular shunts: initial experience and technical note

Precipitating hydrophobic injectable liquid is a new liquid embolic agent used mainly for intracranial neurointervention. The agent is ready to use (no shaking is required), since iodine, the radiopaque material, is covalently bonded into the compound. Additionally, due to the absence of tantalum, minimal artifacts are seen on postprocedure follow-up CT scans, and the agent penetrates into vessels smaller than 10 µm. The authors report their initial experience with the use of this agent in neurovascular intervention.

Initial experience with precipitating hydrophobic injectable liquid in cerebral arteriovenous malformations

BACKGROUND

Precipitating hydrophobic injectable liquid is a newly introduced liquid embolic agent for endovascular embolization with some technical advantages over other liquid embolic agents. We present our initial experience with precipitating hydrophobic injectable liquid in the endovascular treatment of cerebral arteriovenous malformations.

METHODS

From October 2015 to January 2018, 27 patients harboring cerebral arteriovenous malformations underwent endovascular embolization with precipitating hydrophobic injectable liquid 25. Clinical features, angiographic results, procedural details, complications, and follow-up details were retrospectively analyzed.

RESULTS

Twenty-seven patients with cerebral arteriovenous malformations were included. Total obliteration in one endovascular session was confirmed for 14/27 (52%) patients. Partial embolization was attained in 13 patients (48%) in whom staged treatment with following radiosurgery or surgery was planned. No mortality was recorded in this series. Complications during or after the embolization occurred in six of 27 (22.2%) patients.

CONCLUSION

In our initial experience, precipitating hydrophobic injectable liquid has acceptable clinical outcome comparable to other liquid embolic agents. Although this is the largest reported study in arteriovenous malformation treatment with precipitating hydrophobic injectable liquid, further studies are needed to validate its safety and efficacy.

Investigation of a New Version of the Liquid Embolic Agent PHIL with Extra-Low-Viscosity in an Endovascular Embolization Model

BACKGROUND AND PURPOSE

The type and composition of an embolic agent have a relevant influence on the performance of endovascular embolization. The aim of this study was to investigate a new version of the liquid embolic agent precipitating hydrophobic injectable liquid (PHIL) with extra-low-viscosity in an in vivo embolization model.

MATERIALS AND METHODS

Twenty-four embolization procedures were performed in the porcine rete mirabile. Eight embolizations were performed with PHIL 25% low viscosity, Squid 12, and standard PHIL 25%, respectively. Procedure time, required volume of embolic agent, visibility of the embolic agent, embolization control, embolization extent (ie, penetration of the rete mirabile), amount of reflux, and degree of embolization distal to the rete mirabile were assessed.

RESULTS

All embolic agents were adequately visible. The embolization extent was not significantly different among the 3 investigated agents; however, there was a tendency toward a higher embolization extent for PHIL 25% low viscosity (median embolization extent: 88% [PHIL 25% low viscosity]; 65% [Squid 12]; 60% [PHIL 25%]; P = .146). The amount of reflux was significantly lower for the extra-low-viscosity agents PHIL 25% low viscosity and Squid 12 compared with the standard PHIL 25% (median reflux distance: 8 mm [PHIL 25% low viscosity]; 6 mm [Squid 12]; 17 mm [PHIL 25%]; P = .011). All other embolization features did not differ among agents.

CONCLUSIONS

PHIL 25% low viscosity is a promising liquid embolic agent for endovascular embolization, featuring effective distal penetration, adequate visibility, a low amount of reflux, and good flow control.

High-Grade Dural Arteriovenous Fistulas : Use of Kaneka ED Coils with the Marathon Microcatheter for Transvenous Coil Embolization

BACKGROUND

Dural arteriovenous fistulas (DAVF) are commonly encountered lesions that can be treated both transvenously, transarterially or using a combined approach.

OBJECTIVE

Transvenous coil embolization of DAVF is a recognized treatment option but can be challenging. In this context this article presents clinical experience using the Kaneka ED10 ExtraSoft coils in combination with the Marathon microcatheter to treat high grade DAVF. The physical properties of these coils and the microcatheter were also determined.

MATERIAL AND METHODS

All patients with high grade DAVF treated with the Marathon and the Kaneka ED COIL ∞10 ExtraSoft coils were retrospectively identified. The clinical presentation, location, grade of the lesion, clinical and radiological follow-up data were recorded. Bench side studies were performed to determine the physical properties of the Marathon catheter in comparison to the SL10 and Headway Duo as well the maximum width of the Kaneka pusher wire in comparison to Hypersoft, Target and Axium Prime coils.

RESULTS

A total of 8 patients with 9 DAVF with 3 Cognard 3 and 6 Cognard 4 lesions were identified. All the DAVF's were occluded either at the end of the procedure or on follow-up imaging. On bench side tests the Marathon microcatheter had the most flexible distal tip and distal shaft in comparison to the SL10 and Headway Duo. The proximal shaft of the Marathon was stiffer than the SL10. The Kaneka ED COIL ∞10 ExtraSoft had the smallest distal width and were the only coils tested that could be deployed through a Marathon microcatheter.

CONCLUSION

The combination of the Marathon microcatheter and Kaneka ED COIL ∞10 ExtraSoft is useful for the treatment of high grade DAVF.

Imaging artifacts of Onyx and PHIL on conventional CT, cone-beam CT and MRI in an animal model

BACKGROUND AND PURPOSE

A frequently reported drawback of ethylene vinyl alcohol copolymer-based liquid embolic agents is the production of artifacts in diagnostic imaging. New embolic agents, such as Precipitating hydrophobic injectable liquid (PHIL; MicroVention, Tustin, CA, USA), are supposed to induce significantly fewer artifacts. The purpose of this study is to assess the degree of artifacts induced by the liquid embolic agents Onyx (Medtronic Neurovascular, Irvine, CA, USA) and PHIL in conventional computed tomography (CT), cone-beam CT and magnetic resonance imaging (MRI) in an experimental in vivo model.

MATERIALS AND METHODS

In 10 pigs the rete mirabile was embolized with Onyx ( n = 5) or PHIL ( n = 5). After embolization, conventional CT, cone-beam CT and MRI were performed. The degree of artifacts was graded qualitatively (five-point scale; for CT and MRI) and quantitatively (HUs of well-defined regions of interest (ROIs); for CT only).

RESULTS

Artifacts were significantly more severe for Onyx both in the qualitative (e.g. conventional CT: 2 versus 5 (medians); p = 0.008) and in the quantitative image analysis (e.g. cone-beam CT: standard deviation of a ROI near to the embolic agent cast, 94 HU versus 38 HU (medians); p = 0.008). Neither Onyx nor PHIL produced any apparent artifacts in MRI.

CONCLUSION

PHIL produces fewer artifacts than Onyx in conventional CT and cone-beam CT in an experimental in vivo model.

Quantification of tantalum sedimentation rates in liquid embolic agents

Background Endovascular treatment (EVT) of brain arteriovenous malformations has evolved from cyanoacrylate derivatives such as N-butyl cyanoacrylate, an adhesive glue, to ethylene vinyl copolymer-based liquid embolics such as Onyx® and SQUID® dissolved in dimethyl sulfoxide. Although these agents offer several advantages, their rapidly decreasing radiopacity, as a result of the sedimentation of tantalum powder, compromises visual control during EVT. This study aims to quantify and compare tantalum sedimentation rates of several liquid embolic agents, and determine their effects on radiopacity. Methods The rate of sedimentation of liquid embolics Onyx 18®, SQUID 12®, and SQUID 18® was measured after preparation by single x-ray exposures for a period of 30 minutes. The signal-to-noise ratios (SNRs) of the suspension of each liquid embolic was calculated at various time points as tantalum settled out of the suspension. Precipitating Hydrophobic Injectable Liquid (PHIL®) was imaged as a control. Results Onyx 18® demonstrated the fastest sedimentation rate of the liquid embolics analyzed and demonstrated a threefold faster drop in SNR compared to SQUID 18® over 30 minutes. Onyx 18® demonstrated a one and a half times faster drop in SNR compared to SQUID 12®. Although PHIL 25® maintained constant SNR over the same time, it was lower at baseline immediately after preparation compared to tantalum-based liquids. Conclusion Caution during long injections using tantalum-based agents is advised. Onyx 18® has a significantly faster drop in radiopacity compared to SQUID 12® and SQUID 18®. Covalently bonded iodine-based embolics like PHIL® demonstrate constant radiopacity over time.

Increase in fluoroscopic radiation dose in successive sessions of multistage Onyx embolization of brain arteriovenous malformations compared with the first session

BACKGROUND AND PURPOSE

Onyx embolization is a treatment for brain arteriovenous malformations (AVMs). However, multistage embolization usually involves the presence of radiodense Onyx cast from the previous sessions, which may influence the fluoroscopic radiation dose. We compared the fluoroscopic dose between the initial and final embolization sessions.

MATERIALS AND METHOD

From January 2014 to September 2016, 18 patients underwent multistage Onyx embolization (more than twice) for brain AVMs. The total fluoroscopic duration (minutes), dose-area product (DAP, Gy×cm²), and cumulative air kerma (CAK, mGy) of both the frontal and lateral planes were obtained. We compared the frontal and lateral fluoroscopic dose rates (dose/time) of the final embolization session with those of the initial session. The relationship between the injected Onyx volume and radiation dose was tested.

RESULTS

The initial and final procedures on the frontal plane showed significantly different fluoroscopic dose rates (DAP: initial 0.668 Gy×cm²/min, final 0.848 Gy×cm²/min, P=0.02; CAK: initial 12.7 mGy/min, final 23.1 mGy/min, P=0.007). Those on the lateral plane also showed a similar pattern (DAP: initial 0.365 Gy×cm²/min, final 0.519 Gy×cm²/min, P=0.03; CAK: initial 6.2 mGy/min, final 12.9 mGy/min, P=0.01). The correlation between the cumulative Onyx volume (vials) and radiation dose ratio of both planes showed an increasing trend (rho 0.4325-0.7053; P=0.0011-0.0730).

CONCLUSION

Owing to the automatic exposure control function during fluoroscopy, successive Onyx embolization procedures increase the fluoroscopic radiation dose in multistage brain AVM embolization because of the presence of radiodense Onyx mass.

Eyelid arteriovenous malformation treated with pre-surgical embolization: A case report

Background Arteriovenous malformations are potentially serious vascular anomalies that are rarely encountered in the eyelid and require a multidisciplinary approach. Objectives We would like to describe the technical and clinical aspects related to the treatment of palpebral arteriovenous malformation with selective embolization, followed by surgical resection. Methods A 40-year-old patient presented with an isolated high-flow palpebral arteriovenous malformation. Transarterial embolization, using a liquid embolic agent (PHIL™), was performed in this patient. Results Angiographic and clinical follow-up revealed good results with clinical regression of the mass. Conclusion Although endovascular treatment of palpebral arteriovenous malformations is technically challenging, good functional and cosmetic result was achieved. Arteriovenous malformation embolization using PHIL™ seems to be very effective and makes subsequent surgical procedure safe and feasible. Level IV Evidence obtained from multiple time series with or without the intervention, such as case studies. Dramatic results in uncontrolled trials might also be regarded as this type of evidence.

Embolization of palpebral and orbito-frontal fistulas: technical and anatomical considerations in treating high-flow superficial skin lesions with liquid embolics

The treatment of palpebral and periorbital fistulas may be challenging due to the presence of multiple anastomosis with eloquent ophthalmic and intracranial vascular territories. Moreover, cosmetic and functional characteristics of this area pose unique challenges to open surgical approaches and endovascular therapy. We review the advantages and disadvantages of different liquid embolics in treating palpebral and periorbital fistulas as we describe three successfully treated cases. Moreover, we describe important anatomical landmarks that should be considered at the time of treatment of these lesions.

Sacral dural arteriovenous fistulas: a diagnostic and therapeutic challenge – single-centre experience of 13 cases and review of the literature

Background

Sacral dural arteriovenous fistulas (DAVFs) are rare vascular abnormalities of the spine characterised by slowly progressive symptoms that can mimic different myelopathy disorders.

Object

To report our single Institution experience with sacral DAVFs.

Methods

We retrospectively reviewed the clinical records of patients admitted from 1 January 2006 to 31 December 2016 with a diagnosis of sacral DAVFs, treated by endovascular embolisation or surgical clipping. Clinical presentation, imaging characteristics, treatment results and follow-up were analysed.

Results

We identify 13 patients with sacral DAVFs supplied by lateral sacral arteries. Clinical presentation was characterised by different degrees of motor weakness and sphincter disturbances. In all patients, spinal MRI showed spinal cord hyperintensities with enhancement and prominent perimedullary vessels. Selective internal iliac angiography was mandatory to identify the exact location of the fistula. A complete embolisation was achieved in eight patients performing a single endovascular embolisation and in three patients performing a single surgical disconnection: two patients required combined procedures. Follow-up imaging showed a complete resolution of the spinal cord hyperintensities in 81% of patients and a reduction of the intramedullary enhancement in 91%. Gait improvement was observed in 73% of patients, while remaining stable in 27%. Sphincter disturbances improved in 36% of patients and remained stable in 64%.

Conclusion

Awareness of sacral location of DAVFs is critical because standard spinal angiography will not identify sacral supplies, unless internal iliac arteries are properly examined. In our experience, the endovascular treatment show results comparable to surgery when the fistula point is correctly disconnected.

Medial Tentorial Dural Arteriovenous Fistula Embolization: Single Experience with Embolic Liquid Polymer SQUID and Review of the Literature

BACKGROUND

Tentorial dural arteriovenous fistulas (DAVFs) are uncommon, complex fistulas located between the leaves of the tentorium cerebelli with a specific anatomic and clinical presentation characterized by high hemorrhagic risk. We present a rare case of a medial tentorial DAVF successfully managed via transarterial embolization using SQUID liquid polymer.

CASE DESCRIPTION

A 60-year-old woman presented with a history of left progressive hearing loss and tinnitus for >1 year. Cerebral angiography demonstrated the presence of a medial tentorial DAVF with multiple arterial feeders, including the artery of Davidoff and Schechter; reverse venous outflow was observed in the inferior sagittal sinus and in multiple cortical veins. The patient underwent transarterial embolization with SQUID liquid polymer, an embolic agent that provides 2 different viscous formulations to cast the DAVF. The procedure went well without any complication, and the patient regained her preoperative status. In the postprocedural period, the patient experienced complete resolution of tinnitus. At 6 months, she remained asymptomatic, and cerebral angiography confirmed complete, stable occlusion of the fistula and normalization of cerebral deep venous outflow.

CONCLUSIONS

Medial tentorial DAVFs are considered the most complex DAVFs because of their location and extensive vascular supply. Our literature review focused on endovascular treatment of tentorial DAVFs to highlight the usefulness of new embolic agents in management of these diseases. To our knowledge, we report the first successful use of SQUID liquid polymer in management of a tentorial DAVF.

Evaluation of a novel liquid embolic agent (precipitating hydrophobic injectable liquid (PHIL)) in an animal endovascular embolization model

BACKGROUND

The choice of the embolic agent and the embolization technique can have a significant impact on the success of endovascular embolization.

OBJECTIVE

To evaluate a novel iodinated copolymer-based liquid embolic agent (precipitating hydrophobic injectable liquid (PHIL)) in the porcine rete mirabile (RM), serving as an endovascular embolization model. Onyx, as an established liquid embolic agent, served as comparator.

MATERIALS AND METHODS

Sixteen embolization procedures were performed using PHIL (n=8) or Onyx (n=8) as liquid embolic agent. Waiting time between injections was set to 30 or 60 s (n=4 per study group). Survival time after intervention was 2 hours or 7 days. Embolization characteristics (eg, procedure times, number of injections and volume of embolic agent) and embolization extent (percentage of embolized RM in post-interventional x-ray) were assessed. Post-interventional CT and histopathological analyses were performed.

RESULTS

Embolization characteristics and embolization extent were not significantly different for PHIL and Onyx, including subgroups (eg, embolization extent 44% vs 69% (medians); p=0.101). For PHIL, extension of the waiting time from 30 to 60 s led to a significantly higher embolization extent (24% vs 72% (medians); p=0.035). Moderate disintegration and mild inflammation of the embolized blood vessels were present for both embolic agents.

CONCLUSION

PHIL is feasible for transarterial embolization in an acute and subacute endovascular embolization model. In this preliminary experimental in vivo study, embolization characteristics, embolization extent, and biocompatibility seem to be similar to those of Onyx.

Liquid Embolic Agents for Endovascular Embolization: Evaluation of an Established (Onyx) and a Novel (PHIL) Embolic Agent in an In Vitro AVM Model

BACKGROUND AND PURPOSE

Embolization plays a key role in the treatment of arteriovenous malformations. The aim of this study was to evaluate an established (Onyx) and a novel (precipitating hydrophobic injectable liquid [PHIL]) liquid embolic agent in an in vitro AVM model.

MATERIALS AND METHODS

An AVM model was integrated into a circuit system. The artificial nidus (subdivided into 28 honeycomb-like sections) was embolized with Onyx 18 (group Onyx; n = 8) or PHIL 25 (group PHIL; n = 8) with different pause times between the injections (30 and 60 seconds, n = 4 per study group) by using a 1.3F microcatheter. Procedure times, number of injections, embolization success (defined as the number of filled sections of the artificial nidus), volume of embolic agent, and frequency and extent of reflux and draining vein embolization were assessed.

RESULTS

Embolization success was comparable between Onyx and PHIL. Shorter pause times resulted in a significantly higher embolization success for PHIL (median embolization score, 28 versus 18; P = .011). Compared with Onyx, lower volumes of PHIL were required for the same extent of embolization (median volume per section of the artificial nidus, 15.5 versus 3.6 μL; P < .001).

CONCLUSIONS

While the embolization success was comparable for Onyx and PHIL, pause time had a considerable effect on the embolization success in an in vitro AVM model. Compared with Onyx, lower volumes of PHIL were required for the same extent of embolization.

Preliminary experience with precipitating hydrophobic injectable liquid in brain arteriovenous malformations

Advancement in microcatheter design and emergence of new embolic agents offer better results in endovascular treatment of brain arteriovenous malformations (AVMs). Precipitating hydrophobic injectable liquid (PHIL) (Microvention) is a newly introduced dimethyl sulfoxide-based embolic agent for endovascular use. Herein, we present three patients who underwent endovascular treatment of brain AVMs with PHIL, followed by surgical resection. Endovascular features and same-day surgical handling of the new embolic agent PHIL are presented along with histopathologic changes in the acute stage in brain AVMs are presented, and its major differences from Onyx. In our series, PHIL had moderate inflammatory reaction in the acute stage without any associated angionecrosis that is different than Onyx which cause mild inflammatory reaction with angionecrosis. Smallest vessel containing PHIL was 2.9 μm compared to 5 μm with Onyx, which suggests better penetration.

Polymeric materials for embolic and chemoembolic applications

Percutaneous transcatheter embolization procedures involve the selective occlusion of blood vessels. Occlusive agents, referred to as embolics, vary in material characteristics including chemical composition, mechanical properties, and the ability to concurrently deliver drugs. Commercially available polymeric embolics range from gelatin foam to synthetic polymers such as poly(vinyl alcohol). Current systems under investigation include tunable, bioresorbable microspheres composed of chitosan or poly(ethylene glycol) derivatives, in situ gelling liquid embolics with improved safety profiles, and radiopaque embolics that are trackable in vivo. This article reviews commercially available materials used for embolization as well as polymeric materials that are under investigation.

Absence of skin discoloration after transarterial embolization of a subcutaneous auricular arteriovenous malformation with PHIL

BACKGROUND AND OBJECTIVE

One of the treatment options for arteriovenous malformations consists of embolization, with a choice of various embolic agents, with or without subsequent surgical excision. If embolization is offered without subsequent surgery, the embolic material will stay in situ, in which case the consistency and color become important in superficial lesions. The purpose of this case report is to describe if the use of a novel liquid embolic agent (PHIL) is well suited for treatment of superficial AVMs without subsequent surgery.

CASE DESCRIPTION

A 30-year-old male presented with a painful reddish, pulsatile swelling of the left ear that had been present for more than 10 years. Angiography confirmed an arteriovenous malformation supplied by the superficial temporal artery and the posterior auricular artery. The lesion was successfully treated by embolization with PHIL, through the superficial temporal artery. A minute residual shunt, from the posterior auricular artery, was accepted. Immediate disappearance of pulsatile tinnitus was reported. Moreover, return of normal skin color was observed without discomfort from the embolic deposits. This result has been stable throughout one year of clinical follow-up.

CONCLUSION

To our knowledge, this is the first case report describing PHIL embolization as a treatment option for superficial arteriovenous malformations without the necessity for subsequent surgery. The white color and rubbery consistency are beneficial characteristics of PHIL in treatment of subcutaneous lesions, especially in cosmetically relevant locations.