Outcomes of Particle versus Liquid Embolic Materials Used in Middle Meningeal Artery Embolization for the Treatment of Chronic Subdural Hematoma.

BACKGROUND: Early evidence suggests that middle meningeal artery (MMA) embolization is an efficacious minimally invasive neuroendovascular technique for the management of chronic subdural hematoma (cSDH). Particle and liquid embolic materials are commonly used to embolize the MMA; however, studies comparing the safety and outcomes between these 2 materials are limited. METHODS: Patients ≥18 years old who had MMA embolization for cSDH between July 15, 2020 and May 1, 2022 were retrospectively identified from a single-center database. The primary safety, radiation dosage, fluoroscopy time, and radiographic and clinical outcomes were compared between particle and liquid embolization. RESULTS: In a cohort of 116, 48 (41.38%) were treated with liquid embolic material and 68 (58.62%) were treated with particle. The median age of the cohort was 73 years in the particle group and 73.5 years in the liquid embolic group. There was no significant difference in radiation dose or duration among both groups. There was no reported mortality associated with the procedure. One patient experienced nondisabling ischemic stroke in the particle group. Based on imaging follow-up, 3 patients in the particle group and 1 in the liquid embolic group had asymptomatic recurrence. One patient in each group had symptomatic recurrence requiring hematoma evacuation. The index median size of hematoma was 12 mm in the particle group and 11 mm in the liquid embolic group. At approximately 1 month follow-up, the median size of hematoma reduced to 6 mm in both groups. CONCLUSIONS: Our series shows that liquid embolic and particle embolization are equally safe and effective among patients undergoing MMA embolization for management of cSDH.

Dosimetric effects of embolization material artefacts in arteriovenous malformations stereotactic radiosurgery on treatment planning calculation.

Background and Purpose: Stereotactic Radiosurgery (SRS) is a specialized radiotherapy treatment technique for Arteriovenous Malformations (AVM) in which Computed Tomography (CT) images are used for dose calculations. The purpose of this study was to investigate CT image distortions caused by embolic agents and quantify the influence of these distortions on dose calculations. Methods: Eight AVM patients administered embolic agents prior to SRS were included. Original plans were compared to new recalculated plans using two sets of images. The first set was created by masking the embolic material and artefacts, the second was the diagnostic CT images. In addition, treatment plans were created for an anthropomorphic phantom with water inserts, then with known volumes of embolic materials to study the dosimetric effect of each material. Results: Relative to patients' original plans, maximum Monitor Unit (MU) difference was -4.4% with whole brain masking, -1.3% with artefact masking, -4.1% with embolic masking, and -4.5% with artefact-free diagnostic images. Calculated dose differences were within ± 3.5% for all plans. In phantom, Gamma pass rate was 96% for both embolic agents with conformal fields and 99.9% with dynamic arcs. Dose and MU differences in phantom plans were negligible. Conclusion: Relative dose differences between the original plans and the corrected ones were not clinically remarkable. We recommend evaluating the effect of embolic materials on individual patients' plans. The whole brain corrected planning CT images or diagnostic CT images could be utilized to calculate the magnitude of dose reduction caused by embolic materials and correct it if necessary.

Transvenous Embolization with Ethylene Vinyl Alcohol and Arterial Flow Control of a Dural Arteriovenous Fistula of the Isolated Transverse Sinus.

Dural arteriovenous fistulas draining into an isolated sinus often require a multimodal treatment, with transarterial and transvenous approaches.1-6 However, there is no consensus about the injection technique. Some authors suggest filling the sinus with coils in order to have a compact cast without unnecessary migration of the embolic material. We present a case of a patient with left temporal hemorrhage caused by a dural arteriovenous fistula on the isolated left transverse sinus. In this operative video we demonstrate how the arterial flow control during treatment allows us to obtain a compact cast of the embolic material inside the isolated sinus without coils (Video 1).

Urgent Transcatheter Arterial Embolization for Wunderlich Syndrome With Hypovolemic Shock Secondary to Ruptured Renal Angiomyolipoma.

Purpose: Wunderlich syndrome (WS) with hypovolemic shock secondary to ruptured renal angiomyolipoma (rAML) represents an urgent condition. Hence, we reported our experience with transcatheter arterial embolization (TAE) using different embolic materials under this condition. Methods: This retrospective study consisted of 22 patients. Embolic materials including particles, microcoils, and liquid embolic agents were selectively used based on the decisions of interventional radiologists. Technical success was defined as the complete occlusion of bleeding vessels on the final renal angiogram. Clinical success was defined as the absence of re-hemorrhage needed for repeat endovascular or surgery treatment after TAE. Results: The articulated materials were used when WS presented without aneurysms; a combination of particulate materials and microcoils or Glubran 2 alone were used for WS with aneurysms. The technical success based on 24 episodes of TAEs in 22 patients was 100% (24 of 24). Repeat TAE was achieved in two patients with hemorrhages re-occurring two days after the initial embolization with microcoils alone. The clinical success was 90.9% (20 of 22). No nontarget embolization or embolization-related complications occurred during the TAE procedure. Of the patients, 27.3% (6 of 22) experienced minor complications of post-embolization syndrome (PES). During a median follow-up time of 34 months, no recurrent hemorrhage that required repeat endovascular or surgical treatment for hemostasis occurred. Conclusion: Urgent TAE with the selective use of different embolic materials is an effective alternative to control WS with hypovolemic shock secondary to ruptured rAML. The condition of presenting with or without aneurysms may determine the embolic materials employed.

Recent Update of Embolization of Postpartum Hemorrhage.

Postpartum hemorrhage (PPH) is a life-threatening condition and remains a leading cause of maternal mortality. Transcatheter arterial embolization (TAE) is an effective therapeutic strategy for PPH with the advantages of fast speed, repeatability, and the possibility of fertility preservation. We reviewed the vascular anatomy relevant to PPH, the practical details of TAE emphasizing the timing of embolization, and various clinical conditions of PPH according to a recent literature review.

Recent Update of Embolization of Postpartum Hemorrhage

Postpartum hemorrhage (PPH) is a life-threatening condition and remains a leading cause of maternal mortality. Transcatheter arterial embolization (TAE) is an effective therapeutic strategy for PPH with the advantages of fast speed, repeatability, and the possibility of fertility preservation. We reviewed the vascular anatomy relevant to PPH, the practical details of TAE emphasizing the timing of embolization, and various clinical conditions of PPH according to a recent literature review.

The studies about doxorubicin-loaded p(N-isopropyl-acrylamide-co-butyl methylacrylate) temperature-sensitive nanogel dispersions on the application in TACE therapies for rabbit VX2 liver tumor.

Transarterial chemo-embolization (TACE), which combined embolization therapy and chemotherapy, has become the most widely used treatment for unresectable liver cancer. Blood-vessel-embolic materials play key role on TACE. In the present work, doxorubicin-loaded p(N-isopropylacrylamide-co-butyl methylacrylate) nanogels-iohexol dispersions (IBi-D) were reported firstly for TACE therapy to liver cancer. Using inverting-vial method, IBi-D dispersions showed three phases (swollen gel, flowable sol and shrunken gel) as temperature increased. Although Dox had little effect on the CGTs between flowable and shrunken gel, the rheological properties of IBi-D dispersions could greatly improved by Dox. A sustained Dox-release, which was necessary in TACE therapy, was found from IBi-D dispersions in the eluting medium of PBS buffers. The studies about renal artery embolization of normal rabbits indicated that IBi-D dispersions showed good properties in embolizing all kinds of renal arteries (including peripheral, small and large arteries) by controlling their injecting dosages. Angiography and medical evaluation indicated that TACE therapy of IBi-D dispersions has better efficacy on rabbit VX2 liver tumors than TAC treatment of free Dox and TAE treatment of IBi dispersions.

Recent update of embolization of upper gastrointestinal tract bleeding.

Nonvariceal upper gastrointestinal (UGI) bleeding is a frequent complication with significant morbidity and mortality. Although endoscopic hemostasis remains the initial treatment modality, severe bleeding despite endoscopic management occurs in 5-10% of patients, necessitating surgery or interventional embolotherapy. Endovascular embolotherapy is now considered the first-line therapy for massive UGI bleeding that is refractory to endoscopic management. Interventional radiologists need to be familiar with the choice of embolic materials, technical aspects of embolotherapy, and the factors affecting the favorable or unfavorable outcomes after embolotherapy for UGI bleeding.

Safety of bronchial arterial embolization with n-butyl cyanoacrylate in a swine model.

AIM: To compare the efficacy and safety of bronchial artery embolization (BAE) with n-butyl cyanoacrylate (NBCA) and gelatin sponge particles (GSPs). METHODS: Six healthy female swine were divided into two groups to be treated with BAE using NBCA-lipiodol (NBCA-Lp) and using GSPs. The occlusive durability, the presence of embolic materials, the response of the vessel wall, and damage to the bronchial wall and pulmonary parenchyma were compared. RESULTS: No animals experienced any major complication. Two days later, no recanalization of the bronchial artery was observed in the NBCA-Lp group, while partial recanalization was seen in the GSP group. Embolic materials were not found in the pulmonary artery or pulmonary vein. NBCA-Lp was present as a bubble-like space in bronchial branch arteries of 127-1240 µm, and GSPs as reticular amorphous substance of 107-853 µm. These arteries were in the adventitia outside the bronchial cartilage but not in the fine vessels inside the bronchial cartilage. No damage to the bronchial wall and pulmonary parenchyma was found in either group. Red cell thrombus, stripping of endothelial cells, and infiltration of inflammatory cells was observed in vessels embolized with NBCA-Lp or GSP. CONCLUSION: NBCA embolization is more potent than GSP with regard to bronchial artery occlusion, and both materials were present in bronchial branch arteries ≥ 100 µm diameter.

Recent Update of Embolization of Upper Gastrointestinal Tract Bleeding

Nonvariceal upper gastrointestinal (UGI) bleeding is a frequent complication with significant morbidity and mortality. Although endoscopic hemostasis remains the initial treatment modality, severe bleeding despite endoscopic management occurs in 5-10% of patients, necessitating surgery or interventional embolotherapy. Endovascular embolotherapy is now considered the first-line therapy for massive UGI bleeding that is refractory to endoscopic management. Interventional radiologists need to be familiar with the choice of embolic materials, technical aspects of embolotherapy, and the factors affecting the favorable or unfavorable outcomes after embolotherapy for UGI bleeding.

Experimental Evaluation of Embolic Effect: Pure Glue and Glue-Tungsten Mixture

PURPOSE: For the occlusion of a high-flow fistula, glue is an effective embolic agent. In order to visualize glue fluoroscopicaolly, we demonstrated the different embolic effect of pure glue and a glue-tungsten mixture. MATERIALS AND METHODS: A flow phantom model consisted of a circulating pump (Simon varistaltic pump, Manostat Corporation, U.S.A.) connected to a tygon tube (S-50-HL, Norton Performance Plastic Corporation, U.S.A.); flow was maintained by saline at about 4ml/sec. The tygon tube (4.8mm inner diameter) was cut to a length of 60cm; a Y-connector was fitted to the end of its inflow tract and a gauze filter to the end of the outflow tract. A microcatheter was introduced through the Y-connector into the proximal portion of the tube. 1.0cc of pure glue and 0.25g glue-tungsten mixture were each injected rapidly, three times, and in order to observe flow status within the tygon tube, ink was injected. The shape of the glue cast and the pattern of flow arrest were observed and the length of the cast was measured. In an animal experiment, 0.5cc glue with or without tungsten powder was rapidly injected into the brachial artery of the pig and angiographic findings were compared before and after injection. RESULTS: In the flow phantom experiment, the injection of pure glue resulted in complete flow arrest within the tygon tube; the length of the cast was 7cm. Another injection resulted in incomplete flow arrest and a cast lengthof 16cm. A further injection resulted in the complete passage of glue into the gauze filter, and complete flow arrest. An injection of glue-tungsten mixture resulted in incomplete flow arrest, and a cast length of 30cm; in two other injections, glue-tungsten mixtures passed the tygon tube and gauze filter without flow arrest. In the animal experiment, pure glue resulted in complete in complete flow arrest with minimal distal migration of the glue cast. In contrast, glue-tungsten mixture resulted in incomplete flow arrest or distal migration of the cast, with minimal collateral development. CONCLUSION: Pure glue resulted in complete flow arrest within a short distance of the catheter tip. In contrast, a glue-tungsten mixture tended to result in incomplete flow arrest and more distal migration than was the case with pure glue. In a high-flow vascular lesion, a glue-tungsten mixture therefore appears to result in more distal migration than pure glue without tungsten.

Evaluation of Characteristics of Cyanoacrylate-Lipiodol Mixtures Injected in the Different Flow Layers

PURPOSE: To observe the pattern of glue cast formation when glue was injected into the different fow layersof a flow phantom, and to demonstrate the effect in an animal experiment. MATERIALS AND METHODS: A flow phantom model consisted of a circulating pump (Simon varistaltic pump, Manostat Corporation, U.S.A.) connected via a tygon tube with a specially designed glass tube. Flow of about 4ml/sec was maintained by saline. The glass tube consisted of (1) a small-caliber (2.4-3.2mm inner diameter) straight inflow portion (feeder), (2) a round, larg-caliber portion (nidus), and (3) a medium-caliber (6.7mm inner diameter) straight outflow portion (vein). Glue mixed with Lipiodol (glue: Lipiodol=1:1-3:1) was loaded into a 1cc syringe and slowly injected through a microcatheter ; cast formation along the glass tube was observed. The feeder and nidus portions were injected twelve times and the shape of the cast was compared. In an animal experiment, glue at various concentrations was used to stop rapid flow through a surgically-constructed arteriovenous fistula in porcine carotid artery. RESULTS: When mixture was injected into the straight inflow portion (1), it formed a cast along the wall of the glass tube, with a large cast in the nidus portion. Further injection caused enlargement of the cast in the nidus, but no change in the wall of the inflow portion. When mixture was injected into the nidus portion (2) of the glass tube, a cast formed continuously within the nidus. In the animal experiment, rapid injection of glue at a high conentration staunched flow through the arteriovenous fistula. CONCLUSION: Glue-Lipiodol mixture can be injected slowly and continuously under the surface of the polymerized glue cast which forms along the wall or slow flow portion (nidus) of the glass tube in an experimental flow phantom. However, the effect did not appear during rapid flow in the animal arteriovenous fistular model in which only rapid injection of glue which was either pure or at a glue concentration of more than 75% was effective.