Post-Embolization Dynamic Changes in Obsidio Conformable Embolic: Volume and Radiodensity Analysis

Post-Embolization Dynamic Changes in Obsidio Conformable Embolic: Volume and Radiodensity Analysis | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Post-Embolization Dynamic Changes in Obsidio Conformable Embolic: Volume and Radiodensity Analysis Mohamad Harraka, Radhika Amin, Amir Pourmorteza, Emil Cohen, Saher Sabri, and 5 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8760365/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 4 You are reading this latest preprint version Abstract Purpose: To characterize the temporal dynamic and clinical remodeling of the Obsidio Conformable Embolic™ (Obsidio) post endovascular delivery using longitudinal quantitative CT volumetry and Hounsfield unit (HU) attenuation. Materials and Methods: This retrospective, single-center cohort study included 13 patients (19 vessels) embolized with Obsidio for acute hemorrhage or hypervascular tumor between 2023 and 2025. Patients had at least two follow-up computed tomography (CT) scans within 60 days post-procedure. The primary endpoint was the percent change in embolic cast volume and HU attenuation, measured using standardized Picture Archiving and Communication System (PACS) segmentation tools. Secondary endpoints included assessment for recanalization. Results All embolizations were technically successful (100%). On the first follow-up CT (mean 12 days), the mean Obsidio volume was 93.00 ± 10.56% of the original volume (95% CI: 87.91–98.09, p = 0.0098). On the second follow-up (mean 21 days), the volume was 80.77 ± 18.50% of baseline volume (95% CI: 68.34–93.20, p = 0.0063), representing 19.23% reduction. The average volume reduction rate decelerated from 1.15%/day to 0.99%/day. Concurrently, mean Hounsfield unit attenuation increased by 5.26 ± 7.57% (p = 0.044) on the final follow-up CT scans. No evidence of recanalization, distal embolization, or cast fragmentation was observed on any of CT scans. Conclusion The Obsidio embolic cast undergoes progressive reduction in volume and increase in HU attenuation over two months without evidence of vessel recanalization. This temporal dynamic of Obsidio embolic is consistent with bioresorption of its gelatin and water components, supporting the concept of persistent occlusion via in vivo remodeling. Bleed Embolization Obsidio Volume Density Figures Figure 1 Figure 2 Figure 3 Introduction The management of active hemorrhage relies on a multimodal approach, encompassing mechanical, thermal, and chemical strategies to achieve hemostasis [ 1 , 2 ]. In the realm of interventional radiology, transarterial embolization (TAE) is established as a primary image-guided modality for controlling hemorrhage, supported by Society of Interventional Radiology (SIR) guidelines [ 3 ]. Over time, embolization has advanced significantly, and today, interventionalists have access to a wide range of devices and agents. These include coils, plugs, and balloons to temporary and permanent particulate agents (non-calibrated and calibrated particles), liquids/gels (sclerosing agents, thrombin, in situ precipitating ethylene vinyl alcohol copolymer, and in situ polymerizing N-butyl-2-cyanoacrylate) [ 4 ]. The Obsidio Conformable Embolic™ (Obsidio; Boston Scientific) represents a novel addition to this toolkit. It is a pre-formed, shear-thinning hydrogel composed of bioresorbable gelatin, synthetic silicate nanoplatelets, tantalum, and water [ 5 , 6 ]. Its cohesive, non-adhesive properties are designed for controlled delivery and conformable vessel filling. Early clinical reports have demonstrated a high rate of technical success for hemorrhage control and tumor embolization [ 7 ]. Obsidio’s evolution in vivo is unique, although it is incompletely characterized. As the gelatin matrix resorbs, the embolic cast is hypothesized to undergo volumetric reduction and an increase in Hounsfield unit (HU) attenuation while maintaining vessel occlusion. This imaging-based hypothesis is supported by preclinical data, where a Good Laboratory Practice (GLP) study in a porcine model demonstrated that Obsidio elicits a localized inflammatory response (macrophages, multinucleated giant cells) that breaks down the gelatin and silicate components by 90 days, leaving only tantalum aggregates integrated into a remodeled, permanently occluded lumen by 180 days [ 8 ]. This process is fundamentally distinct from in vivo reactions to other agents, such as coil compaction or liquid embolic recanalization. Standard follow-up imaging may reveal changes in the embolic cast that reflect natural material evolution. There remains a scarcity of quantitative, longitudinal imaging data detailing this process. Therefore, the purpose of this study was to perform a retrospective quantitative computed tomography (CT) analysis to characterize the stability and remodeling behavior of the Obsidio embolic cast over a two-month period following clinical deployment. These findings are instrumental in optimizing the clinical use of Obsidio across a variety of medical indications. Materials and Methods Study Design and Patient Selection This is a retrospective, single-center cohort study from Oct. 2023 till Jan. 2026. All consecutive adult patients (≥ 18 years) who underwent TAE with Obsidio and had at least two post-procedural CT scans available for review within 60 days of the index procedure were enrolled into this study. Indications for embolization were active, non-neurovascular hemorrhage or hypervascular tumor. Exclusion criteria were: life expectancy < 30 days, pregnancy, coagulopathy (INR ≥ 1.8 for femoral or ≥ 2.2 for radial access), severe thrombocytopenia (< 20,000/µL), or embolization for indications outside the study scope (e.g., uterine fibroids, pulmonary AVMs), cancer-related bleeding from non-tumor sites, or a diagnosis of hematologic malignancy. Institutional review board approval was obtained with a waiver of informed consent. Embolization Procedure All procedures were performed via a transfemoral arterial approach. After diagnostic angiography identified the target vessel, a microcatheter was superselectively advanced. Obsidio was uncapped, connected wet-to-wet, and delivered according to the manufacturer's instructions for use. The injection volume was determined by the operator using the clinical endpoint of antegrade flow stasis, confirming technical success. No adjunctive embolic agents were used. Volumetric and HU Attenuation Analysis All patients had CT imaging as part of standard clinical care. The initial post-procedural CT was typically obtained within 24 hours. Follow-up CT scans (non-contrast and contrast-enhanced phases) were acquired based on clinical indication. For volumetric and densitometric analysis, non-contrast series were utilized to isolate the radiopaque tantalum signal of the Obsidio cast. Quantification was performed using the volumetric segmentation tool within the Visage Picture Archiving and Communication System (PACS) platform (Visage Imaging). The embolic cast in each treated vessel was manually segmented on each available non-contrast CT scan by a single reader. The software calculated the total cast volume in mm³ and the mean HU attenuation within the segmented volume. Each vessel was analyzed independently. Figure 1 depicts the temporal sequence of the study. All patients underwent transarterial embolization using Obsidio. A baseline non-contrast CT scan was obtained post-procedurally to establish the initial cast volume (V₀) and radiodensity (HU₀). Patients then received at least one follow-up CT scan within 60 days (First Follow-up, V₁, HU₁). A subset of patients underwent a second follow-up CT, also within the 60-day window (Second Follow-up, V₂, HU₂). The primary outcome was the change in embolic volume calculated between V₀ and V₁/V₂ and radiodensity between HU₀ and HU₁/HU₂. Secondary endpoints included the rate of volume reduction (%/day) and assessment for recanalization. Outcome Measures and Statistical Analysis The primary endpoint was the change in Obsidio embolic cast volume and HU attenuation between the initial post-procedural CT and subsequent follow-up scans. Secondary endpoints included the rate of volume reduction (%/day) and the radiologic presence or absence of recanalization, defined as contrast opacification within or around the cast on angiographic phases. Descriptive statistics were reported as mean ± standard deviation. A paired t-test was used to compare the embolic volume at baseline to the volume at each follow-up time point. Statistical significance was set at p < 0.05. Results Patient and Procedural Characteristics Thirteen patients (mean age 63 ± 15 years; 9 male and 4 female) met the inclusion criteria. Nine patients had a single artery embolized, two patients had two arteries embolized, and two patients had three arteries embolized, for a total of 19 vessels embolized. The treated vessels included visceral branches (gastroduodenal, gastric, adrenal, renal; n=7), intercostal arteries (n=8), and inferior epigastric/internal mammary arteries (n=4). Treated vesselsembolized with 0.274 ± 0.073 mL of Obsidio, based on the interventionist intraoperative report. The indication was active hemorrhage in 18 vessels (94.7%) and a peripheral artery aneurysm in one vessel (5.3%). All procedures (100%) achieved technical success with immediate cessation of bleeding. Mean fluoroscopy time was 17 ± 11 minutes, with a cumulative air kerma of 587 ± 370 mGy. Volumetric Analysis All patients had a first follow-up CT at a mean of 12 days post-embolization. Eight patients (11 vessels) had a second follow-up CT at a mean of 21 days. The quantitative change in volume is summarized in Table 1. At the first follow-up, the mean Obsidio volume was 93.00 ± 10.56% (95% CI: 87.91 - 98.09), of the original post-procedural volume, representing a significant 7% reduction (p = 0.0098). At the second follow-up, the mean volume further decreased to 80.77 ± 18.50% (95% CI: 68.34 - 93.20), of baseline, corresponding to a net 19.23% reduction from the initial volume (p = 0.0063). The average rate of volume reduction decelerated over time, measuring 1.15%/day between the initial and first follow-up, and 0.99%/day between the initial and second follow-up. A representative case demonstrates the progressive volumetric reduction of the embolic cast over time, as shown in Figure 2. The cast volume decreased from 290.1 mm³ post-procedurally to 280.1 mm³ at 10 days and 235.2 mm³ at 32 days, while maintaining a cohesive morphology without evidence of recanalization. The observed volumetric reduction over time is summarized in a scatter plot (Figure 3), which shows the decreasing trend in individual cast volumes from baseline to final follow-up. Radiodensity Analysis Analysis of the embolic cast's mean Hounsfield unit (HU) attenuation revealed a non-significant trend toward increasing HU attenuation at the first follow-up, with a mean change of +3.95% (±10.80%; p = 0.13), equivalent to an average increase of 1.09% per day. At the second follow-up, this increase in attenuation reached statistical significance, with a mean change of +5.26% (±7.57%; p = 0.044) from baseline, corresponding to a slower average rate of 0.26% per day. The quantitative change in Hounsfield Unit (HU) attenuation is summarized in Table 1. Assessment for Recanalization No evidence of recanalization, distal embolization, or cast fragmentation was observed on any follow-up CT angiogram. The morphology of the embolic material remained smooth and contiguous on all multiplanar reconstructions. Availability of data and materials The datasets used and analyzed during the current study are available from the corresponding author on reasonable request. Discussion This quantitative imaging study provides evidence that the Obsidio embolic cast undergoes a progressive, predictable reduction in volume and increase in radiodensity over a two-month period following endovascular delivery. This finding is consistent with the hypothesis of in vivo bioresorption of its gelatin and water components. The observed volumetric decrease, approximately 7% from baseline to the first follow-up and 19% from baseline to the second follow-up, occurred without any radiologic evidence of vessel recanalization. This distinction is critical for clinical interpretation, as a shrinking cast on follow-up imaging may indicate a transition toward a more stable structure as non-resorbable components, such as tantalum, become the dominant elements of the material. The decelerating rate of volume loss (from 1.15%/day to 0.99 %/day) suggests an initial phase of more rapid gelatin hydrolysis and water diffusion, transitioning to a stable scaffold dominated by the non-resorbable tantalum components. The concurrent measurements of volumetric reduction and increasing HU attenuation provide a more complete picture of the cast's in vivo evolution. The significant increase in mean HU attenuation at the second follow-up, alongside the significant decrease in volume, is consistent with the bioresorption of the lower-attenuation gelatin matrix and the resultant relative concentration of the higher-attenuation tantalum component within the persistent cast [5,6]. This behavior, a form of biomimetic remodeling, is supported by preclinical models showing that a localized inflammatory response degrades the gelatin and silicate components, leaving tantalum integrated into a permanently fibrosed lumen over 90-180 days [8]. The decelerating rate of HU attenuation increase (1.09% per day at 12 days versus 0.26% per day at 21 days) parallels the decelerating rate of volumetric loss, suggesting the most rapid phase of gelatin resorption occurs within the first several weeks post-embolization. These correlated imaging metrics help differentiate active material remodeling from passive mechanical compression as the primary driver of cast volume loss, supporting the premise of a predictable biomimetic degradation process rather than uncontrolled fragmentation or washout. The absence of recanalization in this cohort is a favorable outcome, indicating that the remodeling process does not compromise the primary goal of hemorrhage control. This stability may offer theoretical advantages over permanent implants that can compact or incite chronic inflammation. However, the long-term clinical implications of this slow remodeling, including its effect on permanent vessel fibrosis, warrant investigation. The primary residual inorganic component, tantalum, has an established biocompatibility profile from its long-term use in orthopedic and dental implants [9], which may mitigate concerns regarding its permanent retention. This study has several limitations. Its retrospective design and reliance on clinically indicated imaging introduced variability in follow-up timing. The small sample size (13 patients, 19 vessels), while sufficient to detect a statistically significant volumetric change, limits generalizability and precludes meaningful subgroup analysis. The cohort combined high-flow traumatic hemorrhage with a single aneurysm case, introducing pathophysiological heterogeneity that may influence remodeling kinetics. Furthermore, CT volumetry, while objective for measuring tantalum-filled cast volume, cannot delineate the evolving tissue-cast interface or definitively distinguish between active bioresorption and passive compression; histopathological correlation was not available. Prospective studies with standardized imaging time points are needed to refine the understanding of this temporal evolution. Direct comparative studies against established embolic agents (e.g., coils, particles, EVOH) are essential to determine if the unique remodeling behavior of Obsidio translates into differences in patient-centered outcomes, such as rates of re-bleeding, post-embolization syndrome, or long-term vessel patency. In conclusion, longitudinal CT volumetry and densitometry demonstrate that Obsidio undergoes a significant, predictable reduction in volume over two months post-embolization, while concurrently increasing in HU attenuation and maintaining vascular occlusion without recanalization. This imaging profile supports the mechanism of in vivo biomimetic remodeling, characterized by the bioresorption of the gelatin matrix and stabilization and continued radiopacity by non-resorbable components. While these findings define the expected temporal evolution of the embolic cast, prospective and comparative research is necessary to establish whether this unique remodeling behavior translates into measurable long-term clinical advantages. Declarations Availability of data and materials The datasets used and analyzed during the current study are available from the corresponding author on reasonable request. References Schroll R, Smith A, McSwain NE et al (2020) Control of severe, life-threatening external bleeding in the out-of-hospital setting: a systematic review. Prehosp Emerg Care 24(2):287–294. 10.1080/10903127.2020.1743801 Rossaint R, Bouillon B, Cerny V et al (2019) The diagnosis and treatment of acute traumatic bleeding and coagulopathy: updated guideline from the European guideline on management of major bleeding and coagulopathy following trauma. Dtsch Arztebl Int 116(49):852–860. 10.3238/arztebl.2019.0852 Patel IJ, Rahim S, Davidson JC, Society of Interventional Radiology Standards of Practice Committee; Canadian Association for Interventional Radiology et al (2019) Cardiovascular and Interventional Radiological Society of Europe. Society of Interventional Radiology Consensus Guidelines for the Periprocedural Management of Thrombotic and Bleeding Risk in Patients Undergoing Percutaneous Image–Guided Interventions—Part II. J Vasc Interv Radiol 30(8):1168–1184e1. 10.1016/j.jvir.2019.04.017 Ierardi AM, Piacentino F, Pesapane F, Carnevale A, Curti M, Fontana F et al (2020) Basic embolization techniques: tips and tricks. Acta Biomed 91(8–S):71–80. 10.23750/abm.v91i8–S.9974 Gulsen F, Samanci C, Demirdag C, Jabbarzadeh E, Albadawi H, Sayman H et al (2023) Obsidio Conformable Embolic: first-in-human clinical study. J Vasc Interv Radiol 34(6):e29–e70 Albadawi H, Altun I, Hu J, Zhang Z, Panda A, Kim HJ, Khademhosseini A, Oklu R (2020) Nanocomposite Hydrogel with Tantalum Microparticles for Rapid Endovascular Hemostasis. Advanced science (Weinheim, Baden-Wurttemberg, Germany), 8(1), 2003327. https://doi.org/10.1002/advs.202003327 Ahmed O, Karageorgiou J, Kumar A, Patel M, Jones J, Nezami N (2025) Real-world clinical experience with Obsidio Conformable Embolic. CVIR Endovasc 8(1):15. 10.1186/s42155-025-00555-w Boston Scientific Corporation standard response letter PI-2049801-AA (2024) Marlborough (MA): Boston Scientific Mani G, Porter D, Grove K, Collins S, Ornberg A, Shulfer R (2022) A comprehensive review of biological and materials properties of Tantalum and its alloys. J Biomed Mater Res A 110(6):1291–1306. 10.1002/jbm.a.37373 Epub 2022 Feb 13. PMID: 35156305 Table 1 Table 1: Longitudinal CT Measurements of Obsidio Embolic Cast Volume and Hounsfield Unit (HU) Attenuation Following Embolization: Serial quantitative measurements from baseline post-procedural CT to first and second follow-up. Values are presented as mean. Percent changes and daily rates of change are calculated relative to baseline measurements. Statistical significance was determined using a paired t-test. *p-value < 0.05 Longitudinal CT Measurements of Obsidio Embolic Cast Volume and Hounsfield Unit (HU) Attenuation Baseline 1 st Follow Up Changes P Value 2 nd Follow Up Changes P Value Preserved Volume (%) 100 93.00 0.0098 80.77 0.0063 Δ Volume Decrease/Day (%/d) 0 1.12 0.0306 0.99 0.0049 HU Increase (%) 0 3.95 0.1279 5.26 0.0439 Δ HU Increase/Day (%/d) 0 1.10 0.3170 0.30 0.0730 Cite Share Download PDF Status: Under Review Version 1 posted Reviewers agreed at journal 24 Mar, 2026 Reviewers invited by journal 05 Mar, 2026 Editor assigned by journal 13 Feb, 2026 First submitted to journal 08 Feb, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8760365","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":601022589,"identity":"f5d71ee1-e94e-4d16-84f5-c3b65b665c4d","order_by":0,"name":"Mohamad Harraka","email":"","orcid":"","institution":"Georgetown University School of Medicine","correspondingAuthor":false,"prefix":"","firstName":"Mohamad","middleName":"","lastName":"Harraka","suffix":""},{"id":601022590,"identity":"ccf731cd-0e73-4f50-b0db-fe00b344b18a","order_by":1,"name":"Radhika Amin","email":"","orcid":"","institution":"Georgetown University School of 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04:28:18","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8760365/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8760365/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":104343383,"identity":"964789c3-cc6f-4453-901c-151a5265e754","added_by":"auto","created_at":"2026-03-10 17:10:40","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":638648,"visible":true,"origin":"","legend":"\u003cp\u003eStudy design schematic for longitudinal CT volumetry of Obsidio embolic casts\u003c/p\u003e","description":"","filename":"renamed7c614.png","url":"https://assets-eu.researchsquare.com/files/rs-8760365/v1/66df52b6cf66a956dc3b8d6e.png"},{"id":104343376,"identity":"103e59f8-fb9f-4948-b440-b4862b209c6f","added_by":"auto","created_at":"2026-03-10 17:10:37","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":1840245,"visible":true,"origin":"","legend":"\u003cp\u003eSerial axial CT images with volumetric segmentation (green overlay) illustrating the progressive reduction in volume of a cohesive Obsidio embolic cast over 32 days. The cast maintained morphological integrity without evidence of recanalization or fragmentation. Volumes: (A) 290.1 mm³ (baseline), (B) 280.1 mm³ (10-day follow-up), (C) 235.2 mm³ (32-day follow-up). This corresponds to a net volume loss of 18.9%.\u003c/p\u003e","description":"","filename":"renamed7d1fa.png","url":"https://assets-eu.researchsquare.com/files/rs-8760365/v1/97133820bc5cc15522b5bbc3.png"},{"id":104343359,"identity":"d3d255ef-ab81-46f6-a417-a753f08d7531","added_by":"auto","created_at":"2026-03-10 17:10:31","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":152018,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003ePercentage change in Obsidio volume over time. \u003c/strong\u003eScatter plot showing the percent of initial embolic volume measured on follow-up CT scans plotted against days from embolization. Each point represents a single embolized vessel (n = 19 for first follow-up; n = 11 for second follow-up). A negative correlation is observed between time and embolic volume, indicating progressive reduction in Obsidio volume over the first 60 days after embolization. The linear regression trend line demonstrates an average decline of 0.46% of initial volume per day (R² = 0.2436).\u003c/p\u003e","description":"","filename":"DecreaseinObsidioConformablewithTrendLine.png","url":"https://assets-eu.researchsquare.com/files/rs-8760365/v1/9f28e1d0ca26ed75cb7fe603.png"},{"id":104343392,"identity":"c9981c83-0c6a-4292-ba4d-8ac533d01b9c","added_by":"auto","created_at":"2026-03-10 17:10:47","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2969260,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8760365/v1/2f504ae2-c541-45a7-a3ab-41fe515a38aa.pdf"}],"financialInterests":"","formattedTitle":"Post-Embolization Dynamic Changes in Obsidio Conformable Embolic: Volume and Radiodensity Analysis","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe management of active hemorrhage relies on a multimodal approach, encompassing mechanical, thermal, and chemical strategies to achieve hemostasis [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. In the realm of interventional radiology, transarterial embolization (TAE) is established as a primary image-guided modality for controlling hemorrhage, supported by Society of Interventional Radiology (SIR) guidelines [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Over time, embolization has advanced significantly, and today, interventionalists have access to a wide range of devices and agents. These include coils, plugs, and balloons to temporary and permanent particulate agents (non-calibrated and calibrated particles), liquids/gels (sclerosing agents, thrombin, \u003cem\u003ein situ\u003c/em\u003e precipitating ethylene vinyl alcohol copolymer, and \u003cem\u003ein situ\u003c/em\u003e polymerizing N-butyl-2-cyanoacrylate) [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe Obsidio Conformable Embolic\u0026trade; (Obsidio; Boston Scientific) represents a novel addition to this toolkit. It is a pre-formed, shear-thinning hydrogel composed of bioresorbable gelatin, synthetic silicate nanoplatelets, tantalum, and water [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Its cohesive, non-adhesive properties are designed for controlled delivery and conformable vessel filling. Early clinical reports have demonstrated a high rate of technical success for hemorrhage control and tumor embolization [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eObsidio\u0026rsquo;s evolution \u003cem\u003ein vivo\u003c/em\u003e is unique, although it is incompletely characterized. As the gelatin matrix resorbs, the embolic cast is hypothesized to undergo volumetric reduction and an increase in Hounsfield unit (HU) attenuation while maintaining vessel occlusion. This imaging-based hypothesis is supported by preclinical data, where a Good Laboratory Practice (GLP) study in a porcine model demonstrated that Obsidio elicits a localized inflammatory response (macrophages, multinucleated giant cells) that breaks down the gelatin and silicate components by 90 days, leaving only tantalum aggregates integrated into a remodeled, permanently occluded lumen by 180 days [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. This process is fundamentally distinct from \u003cem\u003ein vivo\u003c/em\u003e reactions to other agents, such as coil compaction or liquid embolic recanalization. Standard follow-up imaging may reveal changes in the embolic cast that reflect natural material evolution. There remains a scarcity of quantitative, longitudinal imaging data detailing this process. Therefore, the purpose of this study was to perform a retrospective quantitative computed tomography (CT) analysis to characterize the stability and remodeling behavior of the Obsidio embolic cast over a two-month period following clinical deployment. These findings are instrumental in optimizing the clinical use of Obsidio across a variety of medical indications.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy Design and Patient Selection\u003c/h2\u003e \u003cp\u003eThis is a retrospective, single-center cohort study from Oct. 2023 till Jan. 2026. All consecutive adult patients (\u0026ge;\u0026thinsp;18 years) who underwent TAE with Obsidio and had at least two post-procedural CT scans available for review within 60 days of the index procedure were enrolled into this study. Indications for embolization were active, non-neurovascular hemorrhage or hypervascular tumor. Exclusion criteria were: life expectancy\u0026thinsp;\u0026lt;\u0026thinsp;30 days, pregnancy, coagulopathy (INR\u0026thinsp;\u0026ge;\u0026thinsp;1.8 for femoral or \u0026ge;\u0026thinsp;2.2 for radial access), severe thrombocytopenia (\u0026lt;\u0026thinsp;20,000/\u0026micro;L), or embolization for indications outside the study scope (e.g., uterine fibroids, pulmonary AVMs), cancer-related bleeding from non-tumor sites, or a diagnosis of hematologic malignancy. Institutional review board approval was obtained with a waiver of informed consent.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eEmbolization Procedure\u003c/h3\u003e\n\u003cp\u003eAll procedures were performed via a transfemoral arterial approach. After diagnostic angiography identified the target vessel, a microcatheter was superselectively advanced. Obsidio was uncapped, connected wet-to-wet, and delivered according to the manufacturer's instructions for use. The injection volume was determined by the operator using the clinical endpoint of antegrade flow stasis, confirming technical success. No adjunctive embolic agents were used.\u003c/p\u003e\n\u003ch3\u003eVolumetric and HU Attenuation Analysis\u003c/h3\u003e\n\u003cp\u003eAll patients had CT imaging as part of standard clinical care. The initial post-procedural CT was typically obtained within 24 hours. Follow-up CT scans (non-contrast and contrast-enhanced phases) were acquired based on clinical indication. For volumetric and densitometric analysis, non-contrast series were utilized to isolate the radiopaque tantalum signal of the Obsidio cast.\u003c/p\u003e \u003cp\u003eQuantification was performed using the volumetric segmentation tool within the Visage Picture Archiving and Communication System (PACS) platform (Visage Imaging). The embolic cast in each treated vessel was manually segmented on each available non-contrast CT scan by a single reader. The software calculated the total cast volume in mm\u0026sup3; and the mean HU attenuation within the segmented volume. Each vessel was analyzed independently.\u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e depicts the temporal sequence of the study. All patients underwent transarterial embolization using Obsidio. A baseline non-contrast CT scan was obtained post-procedurally to establish the initial cast volume (V₀) and radiodensity (HU₀). Patients then received at least one follow-up CT scan within 60 days (First Follow-up, V₁, HU₁). A subset of patients underwent a second follow-up CT, also within the 60-day window (Second Follow-up, V₂, HU₂). The primary outcome was the change in embolic volume calculated between V₀ and V₁/V₂ and radiodensity between HU₀ and HU₁/HU₂. Secondary endpoints included the rate of volume reduction (%/day) and assessment for recanalization.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\n\u003ch3\u003eOutcome Measures and Statistical Analysis\u003c/h3\u003e\n\u003cp\u003eThe primary endpoint was the change in Obsidio embolic cast volume and HU attenuation between the initial post-procedural CT and subsequent follow-up scans. Secondary endpoints included the rate of volume reduction (%/day) and the radiologic presence or absence of recanalization, defined as contrast opacification within or around the cast on angiographic phases.\u003c/p\u003e \u003cp\u003eDescriptive statistics were reported as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation. A paired t-test was used to compare the embolic volume at baseline to the volume at each follow-up time point. Statistical significance was set at p\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003e\u003cstrong\u003e\u003cem\u003ePatient and Procedural Characteristics\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThirteen patients (mean age 63 ± 15 years; 9 male and 4 female) met the inclusion criteria. Nine patients had a single artery embolized, two patients had two arteries embolized, and two patients had three arteries embolized, for a total of 19 vessels embolized. The treated vessels included visceral branches (gastroduodenal, gastric, adrenal, renal; n=7), intercostal arteries (n=8), and inferior epigastric/internal mammary arteries (n=4). Treated vesselsembolized with 0.274 ± 0.073 mL of Obsidio, based on the interventionist intraoperative report. The indication was active hemorrhage in 18 vessels (94.7%) and a peripheral artery aneurysm in one vessel (5.3%). All procedures (100%) achieved technical success with immediate cessation of bleeding. Mean fluoroscopy time was 17 ± 11 minutes, with a cumulative air kerma of 587 ± 370 mGy.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eVolumetric Analysis\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll patients had a first follow-up CT at a mean of 12 days post-embolization. Eight patients (11 vessels) had a second follow-up CT at a mean of 21 days. The quantitative change in volume is summarized in Table 1. At the first follow-up, the mean Obsidio volume was 93.00 ± 10.56% (95% CI: 87.91 - 98.09), of the original post-procedural volume, representing a significant 7% reduction (p = 0.0098). At the second follow-up, the mean volume further decreased to 80.77 ± 18.50% (95% CI: 68.34 - 93.20), of baseline, corresponding to a net 19.23% reduction from the initial volume (p = 0.0063). The average rate of volume reduction decelerated over time, measuring 1.15%/day between the initial and first follow-up, and 0.99%/day between the initial and second follow-up. A representative case demonstrates the progressive volumetric reduction of the embolic cast over time, as shown in Figure 2. The cast volume decreased from 290.1 mm³ post-procedurally to 280.1 mm³ at 10 days and 235.2 mm³ at 32 days, while maintaining a cohesive morphology without evidence of recanalization. The observed volumetric reduction over time is summarized in a scatter plot (Figure 3), which shows the decreasing trend in individual cast volumes from baseline to final follow-up.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eRadiodensity Analysis\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAnalysis of the embolic cast's mean Hounsfield unit (HU) attenuation revealed a non-significant trend toward increasing HU attenuation at the first follow-up, with a mean change of +3.95% (±10.80%; p = 0.13), equivalent to an average increase of 1.09% per day. At the second follow-up, this increase in attenuation reached statistical significance, with a mean change of +5.26% (±7.57%; p = 0.044) from baseline, corresponding to a slower average rate of 0.26% per day. The quantitative change in Hounsfield Unit (HU) attenuation is summarized in\u0026nbsp;Table 1.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eAssessment for Recanalization\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNo evidence of recanalization, distal embolization, or cast fragmentation was observed on any follow-up CT angiogram. The morphology of the embolic material remained smooth and contiguous on all multiplanar reconstructions.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eAvailability of data and materials\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used and analyzed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis quantitative imaging study provides evidence that the Obsidio embolic cast undergoes a progressive, predictable reduction in volume and increase in radiodensity over a two-month period following endovascular delivery. This finding is consistent with the hypothesis of \u003cem\u003ein vivo\u003c/em\u003e bioresorption of its gelatin and water components.\u003c/p\u003e\n\u003cp\u003eThe observed volumetric decrease, approximately 7% from baseline to the first follow-up and 19% from baseline to the second follow-up, occurred without any radiologic evidence of vessel recanalization. This distinction is critical for clinical interpretation, as a shrinking cast on follow-up imaging may indicate a transition toward a more stable structure as non-resorbable components, such as tantalum, become the dominant elements of the material. The decelerating rate of volume loss (from 1.15%/day to 0.99 %/day) suggests an initial phase of more rapid gelatin hydrolysis and water diffusion, transitioning to a stable scaffold dominated by the non-resorbable tantalum components.\u003c/p\u003e\n\u003cp\u003eThe concurrent measurements of volumetric reduction and increasing HU attenuation provide a more complete picture of the cast\u0026apos;s \u003cem\u003ein vivo\u0026nbsp;\u003c/em\u003eevolution. The significant increase in mean HU attenuation at the second follow-up, alongside the significant decrease in volume, is consistent with the bioresorption of the lower-attenuation gelatin matrix and the resultant relative concentration of the higher-attenuation tantalum component within the persistent cast [5,6]. This behavior, a form of biomimetic remodeling, is supported by preclinical models showing that a localized inflammatory response degrades the gelatin and silicate components, leaving tantalum integrated into a permanently fibrosed lumen over 90-180 days [8]. The decelerating rate of HU attenuation increase (1.09% per day at 12 days versus 0.26% per day at 21 days) parallels the decelerating rate of volumetric loss, suggesting the most rapid phase of gelatin resorption occurs within the first several weeks post-embolization. These correlated imaging metrics help differentiate active material remodeling from passive mechanical compression as the primary driver of cast volume loss, supporting the premise of a predictable biomimetic degradation process rather than uncontrolled fragmentation or washout.\u003c/p\u003e\n\u003cp\u003eThe absence of recanalization in this cohort is a favorable outcome, indicating that the remodeling process does not compromise the primary goal of hemorrhage control. This stability may offer theoretical advantages over permanent implants that can compact or incite chronic inflammation. However, the long-term clinical implications of this slow remodeling, including its effect on permanent vessel fibrosis, warrant investigation. The primary residual inorganic component, tantalum, has an established biocompatibility profile from its long-term use in orthopedic and dental implants [9], which may mitigate concerns regarding its permanent retention.\u003c/p\u003e\n\u003cp\u003eThis study has several limitations. Its retrospective design and reliance on clinically indicated imaging introduced variability in follow-up timing. The small sample size (13 patients, 19 vessels), while sufficient to detect a statistically significant volumetric change, limits generalizability and precludes meaningful subgroup analysis. The cohort combined high-flow traumatic hemorrhage with a single aneurysm case, introducing pathophysiological heterogeneity that may influence remodeling kinetics. Furthermore, CT volumetry, while objective for measuring tantalum-filled cast volume, cannot delineate the evolving tissue-cast interface or definitively distinguish between active bioresorption and passive compression; histopathological correlation was not available.\u003cbr\u003e\u0026nbsp;Prospective studies with standardized imaging time points are needed to refine the understanding of this temporal evolution. Direct comparative studies against established embolic agents (e.g., coils, particles, EVOH) are essential to determine if the unique remodeling behavior of Obsidio translates into differences in patient-centered outcomes, such as rates of re-bleeding, post-embolization syndrome, or long-term vessel patency.\u003c/p\u003e\n\u003cp\u003eIn conclusion, longitudinal CT volumetry and densitometry demonstrate that Obsidio undergoes a significant, predictable reduction in volume over two months post-embolization, while concurrently increasing in HU attenuation and maintaining vascular occlusion without recanalization. This imaging profile supports the mechanism of \u003cem\u003ein vivo\u003c/em\u003e biomimetic remodeling, characterized by the bioresorption of the gelatin matrix and stabilization and continued radiopacity by non-resorbable components. While these findings define the expected temporal evolution of the embolic cast, prospective and comparative research is necessary to establish whether this unique remodeling behavior translates into measurable long-term clinical advantages.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAvailability of data and materials\u003c/h2\u003e \u003cp\u003eThe datasets used and analyzed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eSchroll R, Smith A, McSwain NE et al (2020) Control of severe, life-threatening external bleeding in the out-of-hospital setting: a systematic review. Prehosp Emerg Care 24(2):287\u0026ndash;294. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1080/10903127.2020.1743801\u003c/span\u003e\u003cspan address=\"10.1080/10903127.2020.1743801\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRossaint R, Bouillon B, Cerny V et al (2019) The diagnosis and treatment of acute traumatic bleeding and coagulopathy: updated guideline from the European guideline on management of major bleeding and coagulopathy following trauma. Dtsch Arztebl Int 116(49):852\u0026ndash;860. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3238/arztebl.2019.0852\u003c/span\u003e\u003cspan address=\"10.3238/arztebl.2019.0852\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePatel IJ, Rahim S, Davidson JC, Society of Interventional Radiology Standards of Practice Committee; Canadian Association for Interventional Radiology et al (2019) Cardiovascular and Interventional Radiological Society of Europe. Society of Interventional Radiology Consensus Guidelines for the Periprocedural Management of Thrombotic and Bleeding Risk in Patients Undergoing Percutaneous Image\u0026ndash;Guided Interventions\u0026mdash;Part II. 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Acta Biomed 91(8\u0026ndash;S):71\u0026ndash;80. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.23750/abm.v91i8\u0026ndash;S.9974\u003c/span\u003e\u003cspan address=\"10.23750/abm.v91i8\u0026ndash;S.9974\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGulsen F, Samanci C, Demirdag C, Jabbarzadeh E, Albadawi H, Sayman H et al (2023) Obsidio Conformable Embolic: first-in-human clinical study. J Vasc Interv Radiol 34(6):e29\u0026ndash;e70\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAlbadawi H, Altun I, Hu J, Zhang Z, Panda A, Kim HJ, Khademhosseini A, Oklu R (2020) Nanocomposite Hydrogel with Tantalum Microparticles for Rapid Endovascular Hemostasis. 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CVIR Endovasc 8(1):15. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1186/s42155-025-00555-w\u003c/span\u003e\u003cspan address=\"10.1186/s42155-025-00555-w\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBoston Scientific Corporation standard response letter PI-2049801-AA (2024) Marlborough (MA): Boston Scientific\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMani G, Porter D, Grove K, Collins S, Ornberg A, Shulfer R (2022) A comprehensive review of biological and materials properties of Tantalum and its alloys. J Biomed Mater Res A 110(6):1291\u0026ndash;1306. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1002/jbm.a.37373\u003c/span\u003e\u003cspan address=\"10.1002/jbm.a.37373\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003eEpub 2022 Feb 13. PMID: 35156305\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"},{"header":"Table 1","content":"\u003cp\u003e\u003cstrong\u003eTable 1: Longitudinal CT Measurements of Obsidio Embolic Cast Volume and Hounsfield Unit (HU) Attenuation Following Embolization:\u0026nbsp;\u003c/strong\u003eSerial quantitative measurements from baseline post-procedural CT to first and second follow-up. Values are presented as mean. Percent changes and daily rates of change are calculated relative to baseline measurements. Statistical significance was determined using a paired t-test. *p-value \u0026lt; 0.05\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" align=\"\" width=\"720\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"6\" style=\"width: 720px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eLongitudinal CT Measurements of Obsidio Embolic Cast Volume and Hounsfield Unit (HU) Attenuation\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 222px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 78px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eBaseline\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e1\u003csup\u003est\u003c/sup\u003e Follow Up\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eChanges\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 84px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eP Value\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e2\u003csup\u003end\u003c/sup\u003e Follow Up\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eChanges\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 102px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eP Value\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 222px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePreserved Volume (%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 78px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e100\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e93.00\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 84px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cu\u003e0.0098\u003c/u\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e80.77\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 102px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cu\u003e0.0063\u003c/u\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 222px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026Delta;\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;Volume Decrease/Day (%/d)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 78px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e0\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e1.12\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 84px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cu\u003e0.0306\u003c/u\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.99\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 102px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cu\u003e0.0049\u003c/u\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 222px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eHU Increase (%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 78px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e0\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e3.95\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 84px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.1279\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e5.26\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 102px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cu\u003e0.0439\u003c/u\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 222px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026Delta;\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;HU Increase/Day (%/d)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 78px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e0\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e1.10\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 84px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.3170\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.30\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 102px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.0730\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"cvir-endovascular","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"cire","sideBox":"Learn more about [CVIR Endovascular](https://www.springer.com/journal/42155)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/cire/default.aspx","title":"CVIR Endovascular","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Bleed, Embolization, Obsidio, Volume, Density","lastPublishedDoi":"10.21203/rs.3.rs-8760365/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8760365/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003ePurpose:\u003c/h2\u003e \u003cp\u003eTo characterize the temporal dynamic and clinical remodeling of the Obsidio Conformable Embolic\u0026trade; (Obsidio) post endovascular delivery using longitudinal quantitative CT volumetry and Hounsfield unit (HU) attenuation.\u003c/p\u003e\u003ch2\u003eMaterials and Methods:\u003c/h2\u003e \u003cp\u003eThis retrospective, single-center cohort study included 13 patients (19 vessels) embolized with Obsidio for acute hemorrhage or hypervascular tumor between 2023 and 2025. Patients had at least two follow-up computed tomography (CT) scans within 60 days post-procedure. The primary endpoint was the percent change in embolic cast volume and HU attenuation, measured using standardized Picture Archiving and Communication System (PACS) segmentation tools. Secondary endpoints included assessment for recanalization.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eAll embolizations were technically successful (100%). On the first follow-up CT (mean 12 days), the mean Obsidio volume was 93.00\u0026thinsp;\u0026plusmn;\u0026thinsp;10.56% of the original volume (95% CI: 87.91\u0026ndash;98.09, p\u0026thinsp;=\u0026thinsp;0.0098). On the second follow-up (mean 21 days), the volume was 80.77\u0026thinsp;\u0026plusmn;\u0026thinsp;18.50% of baseline volume (95% CI: 68.34\u0026ndash;93.20, p\u0026thinsp;=\u0026thinsp;0.0063), representing 19.23% reduction. The average volume reduction rate decelerated from 1.15%/day to 0.99%/day. Concurrently, mean Hounsfield unit attenuation increased by 5.26\u0026thinsp;\u0026plusmn;\u0026thinsp;7.57% (p\u0026thinsp;=\u0026thinsp;0.044) on the final follow-up CT scans. No evidence of recanalization, distal embolization, or cast fragmentation was observed on any of CT scans.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eThe Obsidio embolic cast undergoes progressive reduction in volume and increase in HU attenuation over two months without evidence of vessel recanalization. This temporal dynamic of Obsidio embolic is consistent with bioresorption of its gelatin and water components, supporting the concept of persistent occlusion via \u003cem\u003ein vivo\u003c/em\u003e remodeling.\u003c/p\u003e","manuscriptTitle":"Post-Embolization Dynamic Changes in Obsidio Conformable Embolic: Volume and Radiodensity Analysis","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-03-10 17:09:54","doi":"10.21203/rs.3.rs-8760365/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"","date":"2026-03-24T12:18:33+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-03-05T06:09:34+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-02-13T14:00:35+00:00","index":"","fulltext":""},{"type":"submitted","content":"CVIR Endovascular","date":"2026-02-08T08:47:24+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"cvir-endovascular","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"cire","sideBox":"Learn more about [CVIR Endovascular](https://www.springer.com/journal/42155)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/cire/default.aspx","title":"CVIR Endovascular","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"20452cba-27c3-478d-aafe-3b99ca833f78","owner":[],"postedDate":"March 10th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-03-10T17:09:54+00:00","versionOfRecord":[],"versionCreatedAt":"2026-03-10 17:09:54","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8760365","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8760365","identity":"rs-8760365","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}