{"paper_id":"4055fd00-ee64-4356-ba7e-b02a940ae29e","body_text":"Vessel Curvature and Microcatheter–Detachable Coil Compatibility in Arterial Coil Embolization | 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 Vessel Curvature and Microcatheter–Detachable Coil Compatibility in Arterial Coil Embolization Kenichiro Okumura, Takahiro Ogi, Junichi Matsumoto, Nobuyuki Asato, and 6 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6256551/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Purpose: This study examined whether sharp vessel angulation (≥90–180°) and microcatheter–detachable coil compatibility independently increase coil maldelivery in non-neuro arterial embolization, and how these factors affect technical failure and salvage strategies. Materials and Methods: A single-center, IRB-approved analysis from February 2023 to December 2024 included 451 arterial branch–detachable coil combinations (BCCs) in 119 patients (mean age 64 years, range 32–87). Angulations of 90–180° at the proximal catheter segment and distal tip were evaluated on digital subtraction angiography. Technical failure was defined as inability to deploy the coil as intended, including unraveling or coil shape distortion. A 1:3 propensity score matching (28 failed vs 61 successful BCCs) balanced coil features and target-vessel factors. Mismatch was recorded if coil primary diameter exceeded or fell below microcatheter thresholds. A generalized linear mixed model accounted for within-patient clustering. Results: Coil failure occurred in 28 of 451 BCCs (6.2 %). A 90–180° inversion at the catheter tip (odds ratio [OR], 22; p = 0.008) and mismatch (OR, 4.9; p = 0.03) independently predicted failure. A proximal 90–180° inversion also contributed (OR, 4.5; p = 0.03). Of 28 failures, 21/28 (75%) were mismatched: 16/21 (76%) resolved via mismatch correction, and 5/21 (24%) required repositioning or an alternate coil gauge/length. Proper-match failures (n=7) were treated with thinner or more flexible coils in 6 (85.7%; p < 0.0001). Conclusions: Sharp vessel angulation (≥90–180°) and microcatheter–coil mismatch each heighten maldelivery risk. Repositioning or adjusting coil dimensions can salvage mismatched cases, whereas more flexible coils help in matched cases. Detachable coil embolization Vascular curvature Microcatheter–detachable coil mismatch Coil flexibility Figures Figure 1 Figure 2 Figure 3 Figure 4 Introduction Non-neuro arterial embolization is widely performed to manage acute hemorrhage, tumor devascularization, and elective vessel occlusion in various vascular territories, including the gastrointestinal tract, genitourinary system, and musculoskeletal branches [1, 2]. Among the many available embolic materials, Coil embolization provides precise placement, retrievability, and controlled occlusion [3-5]. Nevertheless, unexpected coil maldelivery continues to occur, manifesting as coil deformation, unraveling, or misplacement, and is frequently linked to pronounced vessel curvature or a mismatch between the microcatheter’s inner diameter and the coil’s primary diameter (microcatheter–detachable coil mismatch) [6-11]. And, the impact of specific anatomical factors—such as branch angulation and vessel tortuosity—on coil performance and complication risk remains only partially understood. Indeed, clinical observations indicate that even mismatches between microcatheters and coil primary diameter can impede smooth delivery, cause abnormal coil extension, or lead to unraveling, potentially compromising both technical success and patient outcomes [7]. Despite various coil and catheter designs, few large-scale investigations have systematically evaluated how anatomic curvature and device compatibility influence coil deployment in non-neuro branches. Therefore, it was hypothesized that pronounced vessel angulation (≥90–180°) and a discrepancy between coil diameter and microcatheter lumen each heighten maldelivery. This retrospective study quantified these risk factors, emphasizing immediate technical outcomes and salvage methods. Material and Methods Study Design and Oversight This single-center retrospective analysis (February 2023–December 2024) was approved by our Institutional Review Board (approval number XXXX-XXX). The requirement for written informed consent was waived in accordance with institutional guidelines. All procedures were conducted in accordance with institutional protocols for research ethics and the tenets of the Declaration of Helsinki. Consecutive patients requiring non-neuro arterial embolization during the study period were identified. Patient and Procedure Selection A total of 567 arterial branch–coil combinations (BCCs) were initially identified in 151 patients. Cases were excluded based on three criteria: (1) use of only high-flow catheters (≥0.022-inch inner diameter)(6 BCCs), (2) presence of stent or plug gaps around the aorta (32 BCCs), and (3) targeting of non-arterial vessels (venous or portal, 78 BCCs). After these exclusions, 451 BCCs remained in 119 patients (mean age, 64 years; range, 32–87). The sample size for this study was determined based on the availability of institutional data within the study period and feasibility considerations, rather than a predefined power analysis. While the number of cases provides a reasonable basis for statistical analysis, the relatively small number of failures (28 cases) may limit statistical power, and results should be interpreted accordingly. As shown in Fig. 1, a detailed flowchart of patient enrollment, exclusion, and propensity score matching is provided to illustrate the selection of the final study cohort. The procedures were performed by four attending interventional radiologists, each with over a decade of experience. The study was designed to focus on both procedural success and patterns of failure, particularly in relation to vascular morphology and coil–catheter compatibility. Definition of Technical Failure Technical success was achieved when the coil fully deployed in the intended segment without requiring retrieval. Technical failure was documented if the coil (1) could not exit the catheter, (2) exhibited major unraveling or “stretching,” or (3) failed to assume a stable shape (e.g., extreme elongation) that required replacement. Although “failure to assume intended shape” can be subjective, procedural notes typically described such events. This real-world approach inherently incorporates some observer bias but mirrors operator decision-making. Microcatheter–Detachable Coil Mismatch Microcatheter–detachable coil mismatch was defined as any microcatheter–coil pairing that exceeded either the manufacturer’s indications or the additional criteria implemented in this study, which were derived from multiple product specifications. In practice, bare coils up to 0.012 inch generally fit microcatheters of 0.019 inch or less, whereas coils of 0.014 inch or larger require catheters of up to 0.021 inch. Fibered coils typically need a microcatheter diameter of at least 0.021 inch, and hydrogel polymer coils (AZUR Soft 3D, Terumo, Tokyo, Japan) are recommended for catheters with an inner diameter of approximately 0.0165–0.021 inch. Any deviation from these thresholds or from explicit manufacturer guidelines was classified as a mismatch. For example, using a 0.020–0.021-inch microcatheter with 0.010–0.012-inch bare coils may allow excess snaking, while placing a 0.012–0.015-inch fibered coil in a 0.019-inch microcatheter can increase frictional forces. In either case, suboptimal coil–catheter compatibility risks procedural difficulty or failure. Microcatheter and Detachable Coil Descriptions A variety of taper and non-taper microcatheters were employed, chosen based on factors such as vessel size and operator preference. Taper models, including BISHOP (Piolax, Yokohama, Japan), Progreat λ19/λ17 (Terumo, Tokyo, Japan), and Velouté Ultra/19 DM (Asahi Intecc, Aichi, Japan), generally exhibited a minimum inner diameter between 0.015 and 0.019 inch. Non-taper models such as MARVEL (Tokai Medical Products, Kasugai, Japan), Excelsior SL10 (Stryker, Fremont, CA, USA), and Lighthouse (Piolax, Yokohama, Japan) had inner diameters in the range of 0.0165 to 0.021 inch. Detachable coils covered a wide range of bare, fibered, and hydrogel polymer types, including Target Ultra, Tetra, and Nano coils (all 0.010 inch, Stryker, Fremont, CA, USA), as well as fibered coils like Interlock (0.012 inch) and Embold (0.015 inch) from Boston Scientific (Marlborough, MA, USA). Secondary coil diameter sizing is generally aimed at a diameter of approximately 10–20% larger than the vessel caliber to ensure adequate wall apposition. In most procedures, microcatheters and coils were selected according to institutional or manufacturer guidelines for compatibility (i.e., pairing microcatheter inner diameter and primary coil diameter within the recommended range). However, in certain emergent cases or when inventory constraints arose, coil–catheter combinations exceeding these recommendations were occasionally used. For the purposes of this study, such instances were classified as “mismatch” as previously defined. Although these off-label combinations were not routinely selected, they were sometimes the only feasible option in urgent situations. For the purposes of this study, “flexible coils” were not defined by a single parameter but were generally considered to be those with a smaller primary diameter (e.g., ≤0.012 inch), a bare rather than fibered design, or an inherently pliable construction. In particular, the AZUR Soft 3D coil (Terumo, Tokyo, Japan) was deemed relatively flexible because its pusher-coil interface includes a joint of comparable suppleness to the coil itself, and it accommodates a wide range of recommended catheter inner diameters (0.0165–0.021 inch). This broad compatibility and reduced stiffness were key factors in labeling it as a flexible option in challenging anatomies. Vascular Anatomy Assessment Two interventional radiologists analyzed digital subtraction angiography (DSA) images to identify a proximal 90–180° inversion (Prox 90–180° Inv.) if the catheter formed a hairpin loop (≥90° but ≤180°) in the proximal path, or a tip 90–180° inversion (Tip 90–180° Inv.) if this occurred within the last 2 cm of the catheter tip. For this study, an “S-shaped configuration” was defined as two or more consecutive curves within the distal 2 cm of the catheter tip that together formed an approximate “S” shape in a single angiographic projection. The study also incorporated a quantitative evaluation of tortuosity, calculated as a meandering index (i.e., the ratio of the traced vessel path length to the straight-line distance between the proximal and distal landmarks) [12]. Higher values in this index indicate greater curvature. To clarify how frictional forces arise when the coil pusher travels through tortuous paths, a schematic diagram (Fig. 2) illustrates the S-shaped and 90–180° inversion configurations. Representative fluoroscopic images further illustrate these configurations in actual procedures (Fig. 3). Management Strategies for Failed Cases Operators sometimes encountered difficulties in coil delivery but were able to salvage the procedure through various strategies. In many instances involving a clear mismatch, the solution involved exchanging the coil for another whose primary diameter or length better conformed to the microcatheter’s specifications. In other situations, the catheter was repositioned to avoid sharp angulations, and a more flexible coil was used to overcome a 90–180° inversion. The decision to select a more pliable coil design was commonly made after observing persistent frictional resistance or excessive snaking on angiography. By modifying the catheter tip position or coil attributes in real time, operators were frequently able to salvage the procedure and achieve stable coil formation within the target vessel. Propensity Score Matching and Statistical Analysis Because only 28 of 451 BCCs (6.2%) failed, a 1:3 nearest-neighbor propensity score matching (with replacement) was performed, balancing coil gauge (0.010–0.012 vs ≥0.014 inch), coil length, taper vs non-taper catheter, microcatheter inner diameter (≤0.019 vs >0.019 inch), and target branch level (≤3rd vs ≥4th order). In this study, branch levels were defined by sequentially counting each division from the aorta: arteries originating directly from the aorta were designated as first-order, their immediate offshoots as second-order, and so forth. Consequently, the celiac artery, common hepatic artery, splenic artery, left gastric artery, gastroduodenal artery, proper hepatic artery, renal artery, intercostal-lumbar arteries, superior and inferior mesenteric arteries, the inferior epigastric artery, the internal thoracic artery, the lingual and maxillary arteries, and the internal iliac artery were categorized up to third-order, and the right gastric artery fell under the fourth-order category based on the definition. Because actual embolization targets often lay distal to these major vessels, each target’s branch level was determined accordingly. Subsequently, 28 failed and 61 successful BCCs were compared. Fisher’s exact or t-tests/Mann–Whitney U tests were used for univariate comparisons. A generalized linear mixed model logistic regression (random intercept by patient) was used for multivariable analysis, with proximal 90–180° inversion, tip 90–180° inversion, S-shaped tip, quantitative tortuosity, and mismatch as covariates. Odds ratios (OR) and 95% confidence intervals (CI) were calculated, with p < 0.05 denoting significance. Analyses were conducted using GraphPad Prism (10.4.1), Python (3.13), and R (4.2.2). Results Baseline Characteristics Before propensity score matching (PSM), 28 failed branch–coil combinations (BCCs) from 12 patients and 423 successful BCCs from 107 patients were identified. Table 1 presents the baseline characteristics and standardized mean differences (SMD) before and after 1:3 nearest-neighbor matching with replacement, showing that the SMD values in key variables (e.g., patient age, catheter type, coil length, and coil diameters) were substantially reduced in the matched dataset. As a result, the final analysis included 28 failed BCCs and 61 matched successful BCCs, indicating improved balance between the failure and success groups compared with the pre-matching cohort. Predictors of Procedural Failure Table 2 and Fig. 4 summarize the association between specific catheter configuration factors and procedural outcomes. In univariable analyses, proximal 90-180° inversion (Prox 90-180° Inv.), tip inversion from 90° to 180° (Tip 90-180° Inv.), the presence of an S-shaped configuration (S-Shape), and microcatheter–detachable coil mismatch were all significantly more frequent in failed cases (p-values of 0.01, <0.0001, <0.0001, and 0.01, respectively). Higher quantitative tortuosity (QT) was also noted in failed cases (mean ± SD, 1.8 ± 0.9 vs. 1.2 ± 0.5; p < 0.0001). However, in the GLMM-based logistic regression, only Prox 90-180° Inv. (p = 0.03; odds ratio [OR], 4.5; 95% CI, 1.1–18), Tip 90-180° Inv. (p = 0.008; OR, 22; 95% CI, 2.2–220), and microcatheter–detachable coil mismatch (p = 0.03; OR, 4.9; 95% CI, 1.2–21) remained independently associated with higher odds of procedural failure. Neither the S-shaped configuration nor quantitative tortuosity showed a significant independent effect after adjusting for other factors. Management Strategies for Failed Cases Table 3 summarizes the management approaches for the 28 failed branch–coil combinations, including resolution of microcatheter–detachable coil mismatch (RCM), repositioning the catheter or choosing an alternate coil gauge/length, and using thinner or more flexible coils. Among the 28 failed procedures, 21 (75%) were categorized as microcatheter–detachable coil mismatch and 7 (25%) as proper match. Three main management strategies were employed to address these failures: (1) resolution of the mismatch (RCM), (2) repositioning the catheter tip or selecting an alternate coil gauge/length, and (3) using a thinner or more flexible coil. Of the 21 mismatch failures, 16 (76%) were salvaged by RCM, whereas 5 (24%) required catheter-tip repositioning or a different coil dimension. In contrast, 6 of the 7 proper-match failures (85.7%) were managed by switching to thinner or more flexible coils. This distribution differed significantly between the mismatch and proper-match groups (p < 0.0001). Discussion When a microcatheter navigates a sharply angled vascular path (90–180° inversions), friction between the coil and the catheter wall increases, impeding smooth insertion and potentially exceeding the coil’s column strength [6, 7, 9, 10, 13]. Prior in vitro studies have demonstrated that severe angulations generate substantial frictional forces, predisposing weaker coil segments to deform. In line with those findings, the present study revealed that sharply angulated anatomy alone—not just microcatheter–detachable coil mismatch—elevates the risk of maldelivery, underscoring the influential role of geometric factors. A mismatch between the microcatheter lumen size and detachable coil primary diameter can amplify frictional challenges. Previous studies have indicated that a narrow lumen creates excessive resistance, potentially causing the coil to deform or unravel, whereas an oversized lumen may lead to uncontrolled movement and reduced coil elasticity, thereby increasing the likelihood of snaking [9, 10, 14]. Forced coil insertion under either scenario can cause the catheter to retract or “kick back,” preventing proper coil placement. The present analysis similarly found that mismatch was a significant risk factor—present in 75% of all failures. Among these mismatch-related failures (n=21), 16 (76%) were salvaged by resolving the mismatch (RCM), while 5 (24%) required catheter-tip repositioning or a different coil gauge/length (p < 0.0001). This outcome suggests that even when an initial mismatch exists, reducing the vascular sharpness (e.g., repositioning the catheter to avoid acute bends) or adjusting coil length/diameter can help the coil deploy more linearly and prevent further complications. However, even properly matched systems faced difficulties when encountering acute angulations, suggesting that geometric factors can outweigh device compatibility alone. Notably, thinner or extra-soft coils proved effective in these high-curvature settings, which aligns with previous reports that flexible devices better accommodate tortuous anatomy [9, 10, 14]. Thus, even in cases where the coil–catheter pairing appears to match, a severely angulated vessel may narrow the lumen sufficiently to necessitate thinner or more flexible coils in practice. Several limitations merit consideration. First, the definition of coil failure was partly subjective. Second, vessel angulation was determined using two-dimensional DSA rather than three-dimensional reconstructions, potentially underestimating the true severity of curvature. Third, high-flow catheters were excluded, limiting the generalizability of these findings to those devices. Fourth, the small number of failures (n=28) constrained statistical power. Fifth, although propensity score matching (PSM) reduced many baseline imbalances, some standardized mean differences (SMDs) remained above 0.2, suggesting possible residual confounding. Nonetheless, the SMDs were substantially lower than before matching, indicating partial improvement in cohort comparability. Finally, many initial failures were ultimately salvaged by repositioning the catheter or switching to a more flexible coil, indicating that maldelivery does not necessarily preclude successful embolization. Conclusion Sharp (90–180°) inversions and microcatheter–detachable coil mismatch each independently elevate the risk of coil maldelivery in non-neuro arterial embolization. Mismatch-related failures can often be salvaged by repositioning or adjusting coil gauge/length, whereas flexible coils may avert maldelivery in matched cases. Declarations Ethics approval and consent to participate The Institutional Review Board approved this retrospective cohort study and waived the requirement for written informed consent. Consent for publication Not applicable Availability of data and material The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request. Competing interests The authors declare that they have no competing interests. Funding Not applicable Author contributions KO , JM , TO, TK: Visualization, Formal analysis, Writing – review & editing. NA, FT, AT: Data curation. KK, HO: Writing – review & editing. KK, SK: Conceptualization, Methodology, Validation, Supervision, Writing – review & editing. Acknowledgements Not applicable References Bauer JR, Ray CE. Transcatheter arterial embolization in the trauma patient: a review. Semin Intervent Radiol. 2004;21(1):11-22. https://doi.org/10.1055/s-2004-831401. Filippiadis DK, Binkert C, Pellerin O, Hoffmann RT, Krajina A, Pereira PL. Cirse Quality Assurance Document and Standards for Classification of Complications: The Cirse Classification System. Cardiovasc Intervent Radiol. 2017;40(8):1141-6. https://doi.org/10.1007/s00270-017-1703-4. Lopera JE. Embolization in Trauma: Review of Basic Principles and Techniques. Semin Intervent Radiol. 2021;38(1):18-33. https://doi.org/10.1055/s-0041-1724015. Hui FK, Fiorella D, Masaryk TJ, Rasmussen PA, Dion JE. A history of detachable coils: 1987-2012. J Neurointerv Surg. 2014;6(2):134-8. https://doi.org/10.1136/neurintsurg-2013-010670. Xiao N, Lewandowski RJ. Embolic Agents: Coils. Semin Intervent Radiol. 2022;39(1):113-8. https://doi.org/10.1055/s-0041-1740939. Miyauchi R, Onozawa S, Kuroki K, Takahashi M. The compatibility experiment: which microcoils are not suitable for which microcatheters? Minim Invasive Ther Allied Technol. 2023;32(3):98-102. https://doi.org/10.1080/13645706.2023.2192788. Oka S, Kohno S, Arizono S, et al. Enhancing precision in vascular embolization: evaluating the effectiveness of the intentional early detachment technique with detachable coils in complex cases. CVIR Endovasc. 2024;7(1):40. https://doi.org/10.1186/s42155-024-00453-7. Beckett JS, Duckwiler GR, Tateshima S, et al. Coil embolization through the Marathon microcatheter: Advantages and pitfalls. Interv Neuroradiol. 2017;23(1):28-33. https://doi.org/10.1177/1591019916667722. Shintai K, Matsubara N, Izumi T, et al. Experimental study of coil delivery wire insertion force in intracranial aneurysm embolization: force discrepancy generated inside the microcatheter through that coil delivery wire passes. Nagoya J Med Sci. 2019;81(2):217-25. https://doi.org/10.18999/nagjms.81.2.217. Sharei H, Alderliesten T, van den Dobbelsteen JJ, Dankelman J. Navigation of guidewires and catheters in the body during intervention procedures: a review of computer-based models. J Med Imaging (Bellingham). 2018;5(1):010902. https://doi.org/10.1117/1.Jmi.5.1.010902. Patriciu A, Mazilu D, Bagga HS, Petrisor D, Kavoussi L, Stoianovici D. An evaluation method for the mechanical performance of guide-wires and catheters in accessing the upper urinary tract. Med Eng Phys. 2007;29(8):918-22. https://doi.org/10.1016/j.medengphy.2006.09.002. Okumura K, Ogi T, Matsumoto J, et al. Hepatic artery stenting with Viabahn. CVIR Endovasc. 2024;7(1):90. https://doi.org/10.1186/s42155-024-00507-w. Lopera JE. Embolization in trauma: principles and techniques. Semin Intervent Radiol. 2010;27(1):14-28. https://doi.org/10.1055/s-0030-1247885. Takashima K, Oike A, Yoshinaka K, et al. Evaluation of the effect of catheter on the guidewire motion in a blood vessel model by physical and numerical simulations. Journal of Biomechanical Science and Engineering. 2017;12(4):17-00181-17-. https://doi.org/10.1299/jbse.17-00181. Tables Table 1. Patient- and Branch–Coil–Level Characteristics Before and After Propensity Score Matching Characteristics Failure (n = 28 BCCs, 12 patients) Pre-Matching Success (n = 423 BCCs, 107 patients) SMD (Pre) Post-Matching Success (n = 61 BCCs, 39 patients) SMD (Post) Patient-level Age (years), mean (SD) 64 (14) 70 (13) 0.48 66 (15) 0.12 Male, n (%) 6 (50.0) 80 (74.8) 0.51 27 (69.2) -0.08 Branch-coil-level Total BCCs 28 423 - 61 - Catheter; Taper, n (%) 7 (25.0) 37 (8.7) -0.68 6 (10.0) 0.53 Catheter; Minimum Inner Diameter ≤ 0.019 inch, n (%) 5 (17.9) 36 (8.5) 0.04 22 (36.1) 0.02 Coil length (cm), mean (SD) 10 (4.4) 15 (11.6) 0.52 11 (5.4) 0.07 Secondary coil diameter (mm), mean (SD) 3.0 (0.9) 4.6 (2.9) 0.73 3.3 (1.1) 0.27 Primary coil diameter ≤ 0.012 inch, n (%) 9 (32.1) 27 (6.4) 0.94 32 (52.5) 0.45 Branches; ≥4th-order branch, n (%) 6 (21.4) 35 (8.3) -0.78 36 (59.0) 0.18 Characteristics are presented at the patient and branch-coil combination (BCC) levels. Patient numbers are listed alongside BCCs to clarify the scale of analysis. Standardized mean differences (SMDs) evaluate the balance between success and failure groups before and after propensity score matching. Table 2. Logistic Regression Results for Catheter Configuration and Tortuosity Variables Failure n (%) N = 28 Success n (%) N = 61 Univariable p-value Multivariable p-value OR (95% CI) Intercept - - - 0.001 0.04 (0.005-0.25) Prox 90-180° Inv. 17 (60.7%) 19 (31.1%) 0.01 0.03 4.5 (1.1-18) Tip 90–180° Inv. 21 (75.0%) 6 (10.0%) <0.0001 0.008 22 (2.2-220) S-Shape 15 (53.6%) 3 (5.0%) <0.0001 0.36 2.6 (0.3-20) QT, mean (SD) 1.8 (0.9) 1.2 (0.5) <0.0001 0.55 0.7 (0.2-2.1) Coil Mismatch 21 (75.0%) 27 (44.3%) 0.01 0.03 4.9 (1.2-21) Prox 90–180° Inv. = 90–180° inversion in the proximal portion of the catheter (excluding the tip); Tip 90–180° Inv. = 90–180° inversion of the distal 2 cm of the catheter tip; S-Shape = S-shaped configuration; Coil Mismatch = Catheter inner diameter–coil primary diameter mismatch; QT = Quantitative Tortuosity. Univariate p-values were obtained by Fisher’s exact test (categorical variables) or t-test / Mann–Whitney U test (continuous variables). Multivariate p-values, odds ratios (OR), and 95% confidence intervals (CI) were derived from the generalized linear mixed model (GLMM) logistic regression. Table 3. Management Strategies for 28 Failed Branch–Detachable Coil Combinations Mismatch Category RCM (n = 16), n (%) Catheter repositioning or alternate coil (n = 6), n (%) Thinner or More Flexible Coil (n = 6), n (%) P -value Microcatheter-detachable coil mismatch (n =21) 16/16 (100%) 5/6 (83.3%) 0/6 (0%) <0.0001 Proper-microcatheter-detachable coil match (n=7) 0/16 (0%) 1/6 (16.7%) 6/6 (100%) RCM = Resolution of microcatheter–detachable coil mismatch; Catheter Repositioning or Alternate Coil = Microcatheter repositioning to avoid kinking or selection of a different coil gauge/length; Thinner or More Flexible Coil = Use of a coil with thinner strands or greater flexibility Cite Share Download PDF Status: Posted Version 1 posted 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. 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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-6256551\",\"acceptedTermsAndConditions\":true,\"allowDirectSubmit\":true,\"archivedVersions\":[],\"articleType\":\"Research Article\",\"associatedPublications\":[],\"authors\":[{\"id\":433660610,\"identity\":\"bdc6d86d-b58c-43c7-a859-39a953a6d1e8\",\"order_by\":0,\"name\":\"Kenichiro Okumura\",\"email\":\"data:image/png;base64,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\",\"orcid\":\"https://orcid.org/0000-0001-8131-7584\",\"institution\":\"Kanazawa University Graduate School of Medical Sciences: Kanazawa Daigaku Daigakuin Iyaku Hokengaku Sogo Kenkyuka Iyaku Hoken Gakuiki Igakurui\",\"correspondingAuthor\":true,\"prefix\":\"\",\"firstName\":\"Kenichiro\",\"middleName\":\"\",\"lastName\":\"Okumura\",\"suffix\":\"\"},{\"id\":433660611,\"identity\":\"21935b4b-db3b-429d-851e-1c377f7dacb7\",\"order_by\":1,\"name\":\"Takahiro Ogi\",\"email\":\"\",\"orcid\":\"https://orcid.org/0000-0001-9999-1278\",\"institution\":\"Kanazawa University Graduate School of Medical Sciences: Kanazawa Daigaku Daigakuin Iyaku Hokengaku Sogo Kenkyuka Iyaku Hoken Gakuiki Igakurui\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Takahiro\",\"middleName\":\"\",\"lastName\":\"Ogi\",\"suffix\":\"\"},{\"id\":433660612,\"identity\":\"9d36d284-9a4c-4ece-8aa0-8a8db2762a59\",\"order_by\":2,\"name\":\"Junichi Matsumoto\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"Kanazawa University Graduate School of Medical Sciences: Kanazawa Daigaku Daigakuin Iyaku Hokengaku Sogo Kenkyuka Iyaku Hoken Gakuiki Igakurui\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Junichi\",\"middleName\":\"\",\"lastName\":\"Matsumoto\",\"suffix\":\"\"},{\"id\":433660613,\"identity\":\"dbede76c-db66-4cf1-97c1-7bdffe2d8332\",\"order_by\":3,\"name\":\"Nobuyuki Asato\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"Kanazawa University Graduate School of Medical Sciences: Kanazawa Daigaku Daigakuin Iyaku Hokengaku Sogo Kenkyuka Iyaku Hoken Gakuiki Igakurui\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Nobuyuki\",\"middleName\":\"\",\"lastName\":\"Asato\",\"suffix\":\"\"},{\"id\":433660614,\"identity\":\"af009abe-e7ae-49b3-a96f-28a738e6eb07\",\"order_by\":4,\"name\":\"Fumihito Toshima\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"Kanazawa University Graduate School of Medical Sciences: Kanazawa Daigaku Daigakuin Iyaku Hokengaku Sogo Kenkyuka Iyaku Hoken Gakuiki Igakurui\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Fumihito\",\"middleName\":\"\",\"lastName\":\"Toshima\",\"suffix\":\"\"},{\"id\":433660615,\"identity\":\"54cec4df-e446-46b5-b8bb-25b7974ba68d\",\"order_by\":5,\"name\":\"Atsushi Takamatsu\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"Kanazawa University Graduate School of Medical Sciences: Kanazawa Daigaku Daigakuin Iyaku Hokengaku Sogo Kenkyuka Iyaku Hoken Gakuiki Igakurui\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Atsushi\",\"middleName\":\"\",\"lastName\":\"Takamatsu\",\"suffix\":\"\"},{\"id\":433660616,\"identity\":\"e5a8391f-d4f6-4b6c-957b-5b397cc2858e\",\"order_by\":6,\"name\":\"Hirohito Osanai\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"Kanazawa University Graduate School of Medical Sciences: Kanazawa Daigaku Daigakuin Iyaku Hokengaku Sogo Kenkyuka Iyaku Hoken Gakuiki Igakurui\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Hirohito\",\"middleName\":\"\",\"lastName\":\"Osanai\",\"suffix\":\"\"},{\"id\":433660617,\"identity\":\"1d8fbb62-97ff-4152-9a9b-dfab126887b3\",\"order_by\":7,\"name\":\"Taichi Kitagawa\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"Kanazawa University Graduate School of Medical Sciences: Kanazawa Daigaku Daigakuin Iyaku Hokengaku Sogo Kenkyuka Iyaku Hoken Gakuiki Igakurui\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Taichi\",\"middleName\":\"\",\"lastName\":\"Kitagawa\",\"suffix\":\"\"},{\"id\":433660618,\"identity\":\"0727b02e-db83-4386-be7d-09ba533042c5\",\"order_by\":8,\"name\":\"Kazuto Kozaka\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"Kanazawa University Graduate School of Medical Sciences: Kanazawa Daigaku Daigakuin Iyaku Hokengaku Sogo Kenkyuka Iyaku Hoken Gakuiki Igakurui\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Kazuto\",\"middleName\":\"\",\"lastName\":\"Kozaka\",\"suffix\":\"\"},{\"id\":433660619,\"identity\":\"9250786b-2c37-42bb-a3ba-1535961ec13e\",\"order_by\":9,\"name\":\"Satoshi Kobayashi\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"Kanazawa University Graduate School of Medical Sciences: Kanazawa Daigaku Daigakuin Iyaku Hokengaku Sogo Kenkyuka Iyaku Hoken Gakuiki Igakurui\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Satoshi\",\"middleName\":\"\",\"lastName\":\"Kobayashi\",\"suffix\":\"\"}],\"badges\":[],\"createdAt\":\"2025-03-18 23:17:19\",\"currentVersionCode\":1,\"declarations\":\"\",\"doi\":\"10.21203/rs.3.rs-6256551/v1\",\"doiUrl\":\"https://doi.org/10.21203/rs.3.rs-6256551/v1\",\"draftVersion\":[],\"editorialEvents\":[],\"editorialNote\":\"\",\"failedWorkflow\":false,\"files\":[{\"id\":79809761,\"identity\":\"a4a09ccc-0e27-4b12-a943-edf0d2040eec\",\"added_by\":\"auto\",\"created_at\":\"2025-04-03 06:22:59\",\"extension\":\"png\",\"order_by\":1,\"title\":\"Figure 1\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":75258,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003e\\u003cstrong\\u003eFlowchart of Patient Enrollment, Exclusion, and Propensity Score Matching\\u003c/strong\\u003e\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"1.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-6256551/v1/241169a206b908300312375c.png\"},{\"id\":79809763,\"identity\":\"92a831b7-c208-43a6-9660-273904cbfd37\",\"added_by\":\"auto\",\"created_at\":\"2025-04-03 06:22:59\",\"extension\":\"png\",\"order_by\":2,\"title\":\"Figure 2\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":165727,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003e\\u003cstrong\\u003eSchematic Diagram of Coil and Coil Pusher Movement Through a Tortuous Catheter, Emphasizing Frictional Forces\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003e(a) The coil pusher moves through an S-shaped catheter, generating friction at contact points.\\u003c/p\\u003e\\n\\u003cp\\u003e(b) The coil pusher passes through a catheter with a 90–180° inversion, creating broad contact with the outer curve. This increased surface area leads to greater friction compared with the S-shaped configuration.\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"2.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-6256551/v1/4d3f70bf241a78c088072aed.png\"},{\"id\":79809765,\"identity\":\"773a93ff-714c-4e66-9262-0f0defda7d8d\",\"added_by\":\"auto\",\"created_at\":\"2025-04-03 06:23:00\",\"extension\":\"png\",\"order_by\":3,\"title\":\"Figure 3\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":319664,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003e\\u003cstrong\\u003eRepresentative Fluoroscopic Images Showing S-Shaped and a 90–180° Inversion Catheter Configurations\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003e(a) Fluoroscopic spot image demonstrating a 180° inversion at the catheter tip (distal segment; arrow).\\u003c/p\\u003e\\n\\u003cp\\u003e(b) Fluoroscopic spot image revealing an S-shaped catheter configuration (arrow).\\u003c/p\\u003e\\n\\u003cp\\u003e(c) Fluoroscopic spot image illustrating a 180° bend in the proximal segment of the catheter (arrow).\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"3.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-6256551/v1/06f1685269aac78418311051.png\"},{\"id\":79809762,\"identity\":\"cb4f44ed-64ca-4f7a-9c3f-e17e1898ba5b\",\"added_by\":\"auto\",\"created_at\":\"2025-04-03 06:22:59\",\"extension\":\"png\",\"order_by\":4,\"title\":\"Figure 4\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":43596,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003e\\u003cstrong\\u003eForest Plot of Multivariate Logistic Regression Results\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eForest plot showing adjusted odds ratios (◆) with 95% confidence intervals (horizontal lines) from the multivariate logistic regression model comparing procedural failure (n=28) to success (n=61). The vertical dashed line represents the reference line (OR=1). Variables left of the line (\\u0026lt;1) favor success; variables right of the line (\\u0026gt;1) favor failure.\\u003c/p\\u003e\\n\\u003cp\\u003eAbbreviations: Prox 90–180° Inv. = 90–180° inversion in the proximal portion of the catheter (excluding the tip); Tip 90–180° Inv. = 90–180° inversion of the distal 2 cm of the catheter tip; S-Shape = S-shaped configuration; QT = Quantitative Tortuosity; Coil Mismatch = Catheter inner diameter–coil primary diameter mismatch.\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"4.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-6256551/v1/58641c54762c1e6ac4586ec7.png\"},{\"id\":80311509,\"identity\":\"67f426d9-f7c4-46a2-a1f7-e4aa6de70119\",\"added_by\":\"auto\",\"created_at\":\"2025-04-10 11:29:30\",\"extension\":\"pdf\",\"order_by\":0,\"title\":\"\",\"display\":\"\",\"copyAsset\":false,\"role\":\"manuscript-pdf\",\"size\":1685849,\"visible\":true,\"origin\":\"\",\"legend\":\"\",\"description\":\"\",\"filename\":\"manuscript.pdf\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-6256551/v1/bd0eaee8-410e-4d29-ba8e-aa234ab04ee7.pdf\"}],\"financialInterests\":\"\",\"formattedTitle\":\"Vessel Curvature and Microcatheter–Detachable Coil Compatibility in Arterial Coil Embolization\",\"fulltext\":[{\"header\":\"Introduction\",\"content\":\"\\u003cp\\u003eNon-neuro arterial embolization is widely performed to manage acute hemorrhage, tumor devascularization, and elective vessel occlusion in various vascular territories, including the gastrointestinal tract, genitourinary system, and musculoskeletal branches\\u0026nbsp;[1, 2]. Among the many available embolic materials, Coil embolization provides precise placement, retrievability, and controlled occlusion [3-5]. Nevertheless, unexpected coil maldelivery continues to occur, manifesting as coil deformation, unraveling, or misplacement, and is frequently linked to pronounced vessel curvature or a mismatch between the microcatheter\\u0026rsquo;s inner diameter and the coil\\u0026rsquo;s primary diameter (microcatheter\\u0026ndash;detachable coil mismatch) [6-11]. And, the impact of specific anatomical factors\\u0026mdash;such as branch angulation and vessel tortuosity\\u0026mdash;on coil performance and complication risk remains only partially understood. Indeed, clinical observations indicate that even mismatches between microcatheters and coil primary diameter can impede smooth delivery, cause abnormal coil extension, or lead to unraveling, potentially compromising both technical success and patient outcomes [7]. Despite various coil and catheter designs, few large-scale investigations have systematically evaluated how anatomic curvature and device compatibility influence coil deployment in non-neuro branches.\\u003c/p\\u003e\\n\\u003cp\\u003eTherefore, it was hypothesized that pronounced vessel angulation (\\u0026ge;90\\u0026ndash;180\\u0026deg;) and a discrepancy between coil diameter and microcatheter lumen each heighten maldelivery. This retrospective study quantified these risk factors, emphasizing immediate technical outcomes and salvage methods.\\u003c/p\\u003e\"},{\"header\":\"Material and Methods\",\"content\":\"\\u003cp\\u003e\\u003cstrong\\u003eStudy Design and Oversight\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eThis single-center retrospective analysis (February 2023\\u0026ndash;December 2024) was approved by our Institutional Review Board (approval number XXXX-XXX). The requirement for written informed consent was waived in accordance with institutional guidelines. All procedures were conducted in accordance with institutional protocols for research ethics and the tenets of the Declaration of Helsinki. Consecutive patients requiring non-neuro arterial embolization during the study period were identified.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003ePatient and Procedure Selection\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eA total of 567 arterial branch\\u0026ndash;coil combinations (BCCs) were initially identified in 151 patients. Cases were excluded based on three criteria: (1) use of only high-flow catheters (\\u0026ge;0.022-inch inner diameter)(6 BCCs), (2) presence of stent or plug gaps around the aorta (32 BCCs), and (3) targeting of non-arterial vessels (venous or portal, 78 BCCs). After these exclusions, 451 BCCs remained in 119 patients (mean age, 64 years; range, 32\\u0026ndash;87). The sample size for this study was determined based on the availability of institutional data within the study period and feasibility considerations, rather than a predefined power analysis. While the number of cases provides a reasonable basis for statistical analysis, the relatively small number of failures (28 cases) may limit statistical power, and results should be interpreted accordingly. As shown in Fig.\\u0026nbsp;1, a detailed flowchart of patient enrollment, exclusion, and propensity score matching is provided to illustrate the selection of the final study cohort. The procedures were performed by four attending interventional radiologists, each with over a decade of experience. The study was designed to focus on both procedural success and patterns of failure, particularly in relation to vascular morphology and coil\\u0026ndash;catheter compatibility.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eDefinition of Technical Failure\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eTechnical success was achieved when the coil fully deployed in the intended segment without requiring retrieval. Technical failure was documented if the coil (1) could not exit the catheter, (2) exhibited major unraveling or \\u0026ldquo;stretching,\\u0026rdquo; or (3) failed to assume a stable shape (e.g., extreme elongation) that required replacement. Although \\u0026ldquo;failure to assume intended shape\\u0026rdquo; can be subjective, procedural notes typically described such events. This real-world approach inherently incorporates some observer bias but mirrors operator decision-making.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eMicrocatheter\\u0026ndash;Detachable Coil Mismatch\\u0026nbsp;\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eMicrocatheter\\u0026ndash;detachable coil mismatch was defined as any microcatheter\\u0026ndash;coil pairing that exceeded either the manufacturer\\u0026rsquo;s indications or the additional criteria implemented in this study, which were derived from multiple product specifications. In practice, bare coils up to 0.012 inch generally fit microcatheters of 0.019 inch or less, whereas coils of 0.014 inch or larger require catheters of up to 0.021 inch. Fibered coils typically need a microcatheter diameter of at least 0.021 inch, and hydrogel polymer coils (AZUR Soft 3D, Terumo, Tokyo, Japan) are recommended for catheters with an inner diameter of approximately 0.0165\\u0026ndash;0.021 inch. Any deviation from these thresholds or from explicit manufacturer guidelines was classified as a mismatch. For example, using a 0.020\\u0026ndash;0.021-inch microcatheter with 0.010\\u0026ndash;0.012-inch bare coils may allow excess snaking, while placing a 0.012\\u0026ndash;0.015-inch fibered coil in a 0.019-inch microcatheter can increase frictional forces. In either case, suboptimal coil\\u0026ndash;catheter compatibility risks procedural difficulty or failure.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eMicrocatheter and Detachable Coil Descriptions\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eA variety of taper and non-taper microcatheters were employed, chosen based on factors such as vessel size and operator preference. Taper models, including BISHOP (Piolax, Yokohama, Japan), Progreat \\u0026lambda;19/\\u0026lambda;17 (Terumo, Tokyo, Japan), and Velout\\u0026eacute; Ultra/19 DM (Asahi Intecc, Aichi, Japan), generally exhibited a minimum inner diameter between 0.015 and 0.019 inch. Non-taper models such as MARVEL (Tokai Medical Products, Kasugai, Japan), Excelsior SL10 (Stryker, Fremont, CA, USA), and Lighthouse (Piolax, Yokohama, Japan) had inner diameters in the range of 0.0165 to 0.021 inch. Detachable coils covered a wide range of bare, fibered, and hydrogel polymer types, including Target Ultra, Tetra, and Nano coils (all 0.010 inch, Stryker, Fremont, CA, USA), as well as fibered coils like Interlock (0.012 inch) and Embold (0.015 inch) from Boston Scientific (Marlborough, MA, USA). Secondary coil diameter sizing is generally aimed at a diameter of approximately 10\\u0026ndash;20% larger than the vessel caliber to ensure adequate wall apposition. In most procedures, microcatheters and coils were selected according to institutional or manufacturer guidelines for compatibility (i.e., pairing microcatheter inner diameter and primary coil diameter within the recommended range). However, in certain emergent cases or when inventory constraints arose, coil\\u0026ndash;catheter combinations exceeding these recommendations were occasionally used. For the purposes of this study, such instances were classified as \\u0026ldquo;mismatch\\u0026rdquo; as previously defined. Although these off-label combinations were not routinely selected, they were sometimes the only feasible option in urgent situations. For the purposes of this study, \\u0026ldquo;flexible coils\\u0026rdquo; were not defined by a single parameter but were generally considered to be those with a smaller primary diameter (e.g., \\u0026le;0.012 inch), a bare rather than fibered design, or an inherently pliable construction. In particular, the AZUR Soft 3D coil (Terumo, Tokyo, Japan) was deemed relatively flexible because its pusher-coil interface includes a joint of comparable suppleness to the coil itself, and it accommodates a wide range of recommended catheter inner diameters (0.0165\\u0026ndash;0.021 inch). This broad compatibility and reduced stiffness were key factors in labeling it as a flexible option in challenging anatomies.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eVascular Anatomy Assessment\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eTwo interventional radiologists analyzed digital subtraction angiography (DSA) images to identify a proximal 90\\u0026ndash;180\\u0026deg; inversion (Prox 90\\u0026ndash;180\\u0026deg; Inv.) if the catheter formed a hairpin loop (\\u0026ge;90\\u0026deg; but \\u0026le;180\\u0026deg;) in the proximal path, or a tip 90\\u0026ndash;180\\u0026deg; inversion (Tip 90\\u0026ndash;180\\u0026deg; Inv.) if this occurred within the last 2 cm of the catheter tip. For this study, an \\u0026ldquo;S-shaped configuration\\u0026rdquo; was defined as two or more consecutive curves within the distal 2 cm of the catheter tip that together formed an approximate \\u0026ldquo;S\\u0026rdquo; shape in a single angiographic projection. The study also incorporated a quantitative evaluation of tortuosity, calculated as a meandering index (i.e., the ratio of the traced vessel path length to the straight-line distance between the proximal and distal landmarks) [12]. Higher values in this index indicate greater curvature. To clarify how frictional forces arise when the coil pusher travels through tortuous paths, a schematic diagram (Fig.\\u0026nbsp;2) illustrates the S-shaped and 90\\u0026ndash;180\\u0026deg; inversion configurations. Representative fluoroscopic images further illustrate these configurations in actual procedures (Fig.\\u0026nbsp;3).\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eManagement Strategies for Failed Cases\\u0026nbsp;\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eOperators sometimes encountered difficulties in coil delivery but were able to salvage the procedure through various strategies. In many instances involving a clear mismatch, the solution involved exchanging the coil for another whose primary diameter or length better conformed to the microcatheter\\u0026rsquo;s specifications. In other situations, the catheter was repositioned to avoid sharp angulations, and a more flexible coil was used to overcome a 90\\u0026ndash;180\\u0026deg; inversion. The decision to select a more pliable coil design was commonly made after observing persistent frictional resistance or excessive snaking on angiography. By modifying the catheter tip position or coil attributes in real time, operators were frequently able to salvage the procedure and achieve stable coil formation within the target vessel.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003ePropensity Score Matching and Statistical Analysis\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eBecause only 28 of 451 BCCs (6.2%) failed, a 1:3 nearest-neighbor propensity score matching (with replacement) was performed, balancing coil gauge (0.010\\u0026ndash;0.012 vs \\u0026ge;0.014 inch), coil length, taper vs non-taper catheter, microcatheter inner diameter (\\u0026le;0.019 vs \\u0026gt;0.019 inch), and target branch level (\\u0026le;3rd vs \\u0026ge;4th order). In this study, branch levels were defined by sequentially counting each division from the aorta: arteries originating directly from the aorta were designated as first-order, their immediate offshoots as second-order, and so forth. Consequently, the celiac artery, common hepatic artery, splenic artery, left gastric artery, gastroduodenal artery, proper hepatic artery, renal artery, intercostal-lumbar arteries, superior and inferior mesenteric arteries, the inferior epigastric artery, the internal thoracic artery, the lingual and maxillary arteries, and the internal iliac artery were categorized up to third-order, and the right gastric artery fell under the fourth-order category based on the definition. Because actual embolization targets often lay distal to these major vessels, each target\\u0026rsquo;s branch level was determined accordingly.\\u003c/p\\u003e\\n\\u003cp\\u003eSubsequently, 28 failed and 61 successful BCCs were compared. Fisher\\u0026rsquo;s exact or t-tests/Mann\\u0026ndash;Whitney U tests were used for univariate comparisons. A generalized linear mixed model logistic regression (random intercept by patient) was used for multivariable analysis, with proximal 90\\u0026ndash;180\\u0026deg; inversion, tip 90\\u0026ndash;180\\u0026deg; inversion, S-shaped tip, quantitative tortuosity, and mismatch as covariates. Odds ratios (OR) and 95% confidence intervals (CI) were calculated, with p \\u0026lt; 0.05 denoting significance. Analyses were conducted using GraphPad Prism (10.4.1), Python (3.13), and R (4.2.2).\\u003c/p\\u003e\"},{\"header\":\"Results\",\"content\":\"\\u003cp\\u003e\\u003cstrong\\u003eBaseline Characteristics\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eBefore propensity score matching (PSM), 28 failed branch\\u0026ndash;coil combinations (BCCs) from 12 patients and 423 successful BCCs from 107 patients were identified. Table 1 presents the baseline characteristics and standardized mean differences (SMD) before and after 1:3 nearest-neighbor matching with replacement, showing that the SMD values in key variables (e.g., patient age, catheter type, coil length, and coil diameters) were substantially reduced in the matched dataset. As a result, the final analysis included 28 failed BCCs and 61 matched successful BCCs, indicating improved balance between the failure and success groups compared with the pre-matching cohort.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003ePredictors of Procedural Failure\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eTable 2 and Fig. 4 summarize the association between specific catheter configuration factors and procedural outcomes. In univariable analyses, proximal 90-180\\u0026deg; inversion (Prox 90-180\\u0026deg; Inv.), tip inversion from 90\\u0026deg; to 180\\u0026deg; (Tip 90-180\\u0026deg; Inv.), the presence of an S-shaped configuration (S-Shape), and microcatheter\\u0026ndash;detachable coil mismatch were all significantly more frequent in failed cases (p-values of 0.01, \\u0026lt;0.0001, \\u0026lt;0.0001, and 0.01, respectively). Higher quantitative tortuosity (QT) was also noted in failed cases (mean \\u0026plusmn; SD, 1.8 \\u0026plusmn; 0.9 vs. 1.2 \\u0026plusmn; 0.5; p \\u0026lt; 0.0001). However, in the GLMM-based logistic regression, only Prox 90-180\\u0026deg; Inv. (p = 0.03; odds ratio [OR], 4.5; 95% CI, 1.1\\u0026ndash;18), Tip 90-180\\u0026deg; Inv. (p = 0.008; OR, 22; 95% CI, 2.2\\u0026ndash;220), and microcatheter\\u0026ndash;detachable coil mismatch (p = 0.03; OR, 4.9; 95% CI, 1.2\\u0026ndash;21) remained independently associated with higher odds of procedural failure. Neither the S-shaped configuration nor quantitative tortuosity showed a significant independent effect after adjusting for other factors.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eManagement Strategies for Failed Cases\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eTable 3 summarizes the management approaches for the 28 failed branch\\u0026ndash;coil combinations, including resolution of microcatheter\\u0026ndash;detachable coil mismatch (RCM), repositioning the catheter or choosing an alternate coil gauge/length, and using thinner or more flexible coils. Among the 28 failed procedures, 21 (75%) were categorized as microcatheter\\u0026ndash;detachable coil mismatch and 7 (25%) as proper match. Three main management strategies were employed to address these failures: (1) resolution of the mismatch (RCM), (2) repositioning the catheter tip or selecting an alternate coil gauge/length, and (3) using a thinner or more flexible coil. Of the 21 mismatch failures, 16 (76%) were salvaged by RCM, whereas 5 (24%) required catheter-tip repositioning or a different coil dimension. In contrast, 6 of the 7 proper-match failures (85.7%) were managed by switching to thinner or more flexible coils. This distribution differed significantly between the mismatch and proper-match groups (p \\u0026lt; 0.0001).\\u003c/p\\u003e\"},{\"header\":\"Discussion\",\"content\":\"\\u003cp\\u003eWhen a microcatheter navigates a sharply angled vascular path (90\\u0026ndash;180\\u0026deg; inversions), friction between the coil and the catheter wall increases, impeding smooth insertion and potentially exceeding the coil\\u0026rsquo;s column strength [6, 7, 9, 10, 13]. Prior in vitro studies have demonstrated that severe angulations generate substantial frictional forces, predisposing weaker coil segments to deform. In line with those findings, the present study revealed that sharply angulated anatomy alone\\u0026mdash;not just microcatheter\\u0026ndash;detachable coil mismatch\\u0026mdash;elevates the risk of maldelivery, underscoring the influential role of geometric factors.\\u003c/p\\u003e\\n\\u003cp\\u003eA mismatch between the microcatheter lumen size and detachable coil primary diameter can amplify frictional challenges. Previous studies have indicated that a narrow lumen creates excessive resistance, potentially causing the coil to deform or unravel, whereas an oversized lumen may lead to uncontrolled movement and reduced coil elasticity, thereby increasing the likelihood of snaking [9, 10, 14]. Forced coil insertion under either scenario can cause the catheter to retract or \\u0026ldquo;kick back,\\u0026rdquo; preventing proper coil placement. The present analysis similarly found that mismatch was a significant risk factor\\u0026mdash;present in 75% of all failures. Among these mismatch-related failures (n=21), 16 (76%) were salvaged by resolving the mismatch (RCM), while 5 (24%) required catheter-tip repositioning or a different coil gauge/length (p \\u0026lt; 0.0001). This outcome suggests that even when an initial mismatch exists, reducing the vascular sharpness (e.g., repositioning the catheter to avoid acute bends) or adjusting coil length/diameter can help the coil deploy more linearly and prevent further complications. However, even properly matched systems faced difficulties when encountering acute angulations, suggesting that geometric factors can outweigh device compatibility alone. Notably, thinner or extra-soft coils proved effective in these high-curvature settings, which aligns with previous reports that flexible devices better accommodate tortuous anatomy [9, 10, 14]. Thus, even in cases where the coil\\u0026ndash;catheter pairing appears to match, a severely angulated vessel may narrow the lumen sufficiently to necessitate thinner or more flexible coils in practice. Several limitations merit consideration. First, the definition of coil failure was partly subjective. Second, vessel angulation was determined using two-dimensional DSA rather than three-dimensional reconstructions, potentially underestimating the true severity of curvature. Third, high-flow catheters were excluded, limiting the generalizability of these findings to those devices. Fourth, the small number of failures (n=28) constrained statistical power. Fifth, although propensity score matching (PSM) reduced many baseline imbalances, some standardized mean differences (SMDs) remained above 0.2, suggesting possible residual confounding. Nonetheless, the SMDs were substantially lower than before matching, indicating partial improvement in cohort comparability. Finally, many initial failures were ultimately salvaged by repositioning the catheter or switching to a more flexible coil, indicating that maldelivery does not necessarily preclude successful embolization.\\u003c/p\\u003e\"},{\"header\":\"Conclusion\",\"content\":\"\\u003cp\\u003eSharp (90\\u0026ndash;180\\u0026deg;) inversions and microcatheter\\u0026ndash;detachable coil mismatch each independently elevate the risk of coil maldelivery in non-neuro arterial embolization. Mismatch-related failures can often be salvaged by repositioning or adjusting coil gauge/length, whereas flexible coils may avert maldelivery in matched cases.\\u003c/p\\u003e\"},{\"header\":\"Declarations\",\"content\":\"\\u003cp\\u003e\\u003cstrong\\u003eEthics approval and consent to participate\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eThe Institutional Review Board approved this retrospective cohort study and waived the requirement for written informed consent.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eConsent for publication\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eNot applicable\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eAvailability of data and material\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eThe datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eCompeting interests\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eThe authors declare that they have no competing interests.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eFunding\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eNot applicable\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eAuthor contributions\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eKO , JM , TO, TK: Visualization, Formal analysis, Writing \\u0026ndash; review \\u0026amp; editing. NA, FT, AT: Data curation. KK, HO: Writing \\u0026ndash; review \\u0026amp; editing. KK, SK: Conceptualization, Methodology, Validation, Supervision, Writing \\u0026ndash; review \\u0026amp; editing.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eAcknowledgements\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eNot applicable\\u003c/p\\u003e\"},{\"header\":\"References\",\"content\":\"\\u003col\\u003e\\n\\u003cli\\u003eBauer JR, Ray CE. Transcatheter arterial embolization in the trauma patient: a review. Semin Intervent Radiol. 2004;21(1):11-22. https://doi.org/10.1055/s-2004-831401.\\u003c/li\\u003e\\n\\u003cli\\u003eFilippiadis DK, Binkert C, Pellerin O, Hoffmann RT, Krajina A, Pereira PL. Cirse Quality Assurance Document and Standards for Classification of Complications: The Cirse Classification System. Cardiovasc Intervent Radiol. 2017;40(8):1141-6. https://doi.org/10.1007/s00270-017-1703-4.\\u003c/li\\u003e\\n\\u003cli\\u003eLopera JE. Embolization in Trauma: Review of Basic Principles and Techniques. Semin Intervent Radiol. 2021;38(1):18-33. https://doi.org/10.1055/s-0041-1724015.\\u003c/li\\u003e\\n\\u003cli\\u003eHui FK, Fiorella D, Masaryk TJ, Rasmussen PA, Dion JE. A history of detachable coils: 1987-2012. J Neurointerv Surg. 2014;6(2):134-8. https://doi.org/10.1136/neurintsurg-2013-010670.\\u003c/li\\u003e\\n\\u003cli\\u003eXiao N, Lewandowski RJ. Embolic Agents: Coils. Semin Intervent Radiol. 2022;39(1):113-8. https://doi.org/10.1055/s-0041-1740939.\\u003c/li\\u003e\\n\\u003cli\\u003eMiyauchi R, Onozawa S, Kuroki K, Takahashi M. The compatibility experiment: which microcoils are not suitable for which microcatheters? Minim Invasive Ther Allied Technol. 2023;32(3):98-102. https://doi.org/10.1080/13645706.2023.2192788.\\u003c/li\\u003e\\n\\u003cli\\u003eOka S, Kohno S, Arizono S, et al. Enhancing precision in vascular embolization: evaluating the effectiveness of the intentional early detachment technique with detachable coils in complex cases. CVIR Endovasc. 2024;7(1):40. https://doi.org/10.1186/s42155-024-00453-7.\\u003c/li\\u003e\\n\\u003cli\\u003eBeckett JS, Duckwiler GR, Tateshima S, et al. Coil embolization through the Marathon microcatheter: Advantages and pitfalls. Interv Neuroradiol. 2017;23(1):28-33. https://doi.org/10.1177/1591019916667722.\\u003c/li\\u003e\\n\\u003cli\\u003eShintai K, Matsubara N, Izumi T, et al. Experimental study of coil delivery wire insertion force in intracranial aneurysm embolization: force discrepancy generated inside the microcatheter through that coil delivery wire passes. Nagoya J Med Sci. 2019;81(2):217-25. https://doi.org/10.18999/nagjms.81.2.217.\\u003c/li\\u003e\\n\\u003cli\\u003eSharei H, Alderliesten T, van den Dobbelsteen JJ, Dankelman J. Navigation of guidewires and catheters in the body during intervention procedures: a review of computer-based models. J Med Imaging (Bellingham). 2018;5(1):010902. https://doi.org/10.1117/1.Jmi.5.1.010902.\\u003c/li\\u003e\\n\\u003cli\\u003ePatriciu A, Mazilu D, Bagga HS, Petrisor D, Kavoussi L, Stoianovici D. An evaluation method for the mechanical performance of guide-wires and catheters in accessing the upper urinary tract. Med Eng Phys. 2007;29(8):918-22. https://doi.org/10.1016/j.medengphy.2006.09.002.\\u003c/li\\u003e\\n\\u003cli\\u003eOkumura K, Ogi T, Matsumoto J, et al. Hepatic artery stenting with Viabahn. CVIR Endovasc. 2024;7(1):90. https://doi.org/10.1186/s42155-024-00507-w.\\u003c/li\\u003e\\n\\u003cli\\u003eLopera JE. Embolization in trauma: principles and techniques. Semin Intervent Radiol. 2010;27(1):14-28. https://doi.org/10.1055/s-0030-1247885.\\u003c/li\\u003e\\n\\u003cli\\u003eTakashima K, Oike A, Yoshinaka K, et al. Evaluation of the effect of catheter on the guidewire motion in a blood vessel model by physical and numerical simulations. Journal of Biomechanical Science and Engineering. 2017;12(4):17-00181-17-. https://doi.org/10.1299/jbse.17-00181.\\u003c/li\\u003e\\n\\u003c/ol\\u003e\"},{\"header\":\"Tables\",\"content\":\"\\u003cp\\u003e\\u003cstrong\\u003eTable 1. Patient- and Branch\\u0026ndash;Coil\\u0026ndash;Level Characteristics Before and After Propensity Score Matching\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003ctable border=\\\"0\\\" cellspacing=\\\"0\\\" cellpadding=\\\"0\\\" width=\\\"1030\\\"\\u003e\\n \\u003ctbody\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd style=\\\"width: 29.3204%;\\\"\\u003e\\n \\u003cp\\u003eCharacteristics\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 20.1942%;\\\"\\u003e\\n \\u003cp\\u003eFailure\\u003c/p\\u003e\\n \\u003cp\\u003e\\u0026nbsp;(n = 28 BCCs, 12 patients)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 20.1942%;\\\"\\u003e\\n \\u003cp\\u003ePre-Matching Success\\u0026nbsp;\\u003c/p\\u003e\\n \\u003cp\\u003e(n = 423 BCCs, 107 patients)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 5.53398%;\\\"\\u003e\\n \\u003cp\\u003eSMD\\u0026nbsp;\\u003c/p\\u003e\\n \\u003cp\\u003e(Pre)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 19.2233%;\\\"\\u003e\\n \\u003cp\\u003ePost-Matching Success\\u0026nbsp;\\u003c/p\\u003e\\n \\u003cp\\u003e(n = 61 BCCs, 39 patients)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 5.53398%;\\\"\\u003e\\n \\u003cp\\u003eSMD\\u0026nbsp;\\u003c/p\\u003e\\n \\u003cp\\u003e(Post)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd style=\\\"width: 29.3204%;\\\"\\u003e\\n \\u003cp\\u003e\\u003cstrong\\u003ePatient-level\\u003c/strong\\u003e\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 20.1942%;\\\"\\u003e\\u003cbr\\u003e\\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 20.1942%;\\\"\\u003e\\u003cbr\\u003e\\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 5.53398%;\\\"\\u003e\\u003cbr\\u003e\\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 19.2233%;\\\"\\u003e\\u003cbr\\u003e\\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 5.53398%;\\\"\\u003e\\u003cbr\\u003e\\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd style=\\\"width: 29.3204%;\\\"\\u003e\\n \\u003cp\\u003eAge (years), mean (SD)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 20.1942%;\\\"\\u003e\\n \\u003cp\\u003e64 (14)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 20.1942%;\\\"\\u003e\\n \\u003cp\\u003e70 (13)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 5.53398%;\\\"\\u003e\\n \\u003cp\\u003e0.48\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 19.2233%;\\\"\\u003e\\n \\u003cp\\u003e66 (15)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 5.53398%;\\\"\\u003e\\n \\u003cp\\u003e0.12\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd style=\\\"width: 29.3204%;\\\"\\u003e\\n \\u003cp\\u003eMale, n (%)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 20.1942%;\\\"\\u003e\\n \\u003cp\\u003e6 (50.0)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 20.1942%;\\\"\\u003e\\n \\u003cp\\u003e80 (74.8)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 5.53398%;\\\"\\u003e\\n \\u003cp\\u003e0.51\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 19.2233%;\\\"\\u003e\\n \\u003cp\\u003e27 (69.2)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 5.53398%;\\\"\\u003e\\n \\u003cp\\u003e-0.08\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd style=\\\"width: 29.3204%;\\\"\\u003e\\n \\u003cp\\u003e\\u003cstrong\\u003eBranch-coil-level\\u003c/strong\\u003e\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 20.1942%;\\\"\\u003e\\u003cbr\\u003e\\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 20.1942%;\\\"\\u003e\\u003cbr\\u003e\\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 5.53398%;\\\"\\u003e\\u003cbr\\u003e\\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 19.2233%;\\\"\\u003e\\u003cbr\\u003e\\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 5.53398%;\\\"\\u003e\\u003cbr\\u003e\\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd style=\\\"width: 29.3204%;\\\"\\u003e\\n \\u003cp\\u003eTotal BCCs\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 20.1942%;\\\"\\u003e\\n \\u003cp\\u003e28\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 20.1942%;\\\"\\u003e\\n \\u003cp\\u003e423\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 5.53398%;\\\"\\u003e\\n \\u003cp\\u003e-\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 19.2233%;\\\"\\u003e\\n \\u003cp\\u003e61\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 5.53398%;\\\"\\u003e\\n \\u003cp\\u003e-\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd style=\\\"width: 29.3204%;\\\"\\u003e\\n \\u003cp\\u003eCatheter; Taper, n (%)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 20.1942%;\\\"\\u003e\\n \\u003cp\\u003e7 (25.0)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 20.1942%;\\\"\\u003e\\n \\u003cp\\u003e37 (8.7)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 5.53398%;\\\"\\u003e\\n \\u003cp\\u003e-0.68\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 19.2233%;\\\"\\u003e\\n \\u003cp\\u003e6 (10.0)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 5.53398%;\\\"\\u003e\\n \\u003cp\\u003e0.53\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd style=\\\"width: 29.3204%;\\\"\\u003e\\n \\u003cp\\u003eCatheter; Minimum Inner Diameter \\u0026le; 0.019 inch, n (%)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 20.1942%;\\\"\\u003e\\n \\u003cp\\u003e5 (17.9)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 20.1942%;\\\"\\u003e\\n \\u003cp\\u003e36 (8.5)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 5.53398%;\\\"\\u003e\\n \\u003cp\\u003e0.04\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 19.2233%;\\\"\\u003e\\n \\u003cp\\u003e22 (36.1)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 5.53398%;\\\"\\u003e\\n \\u003cp\\u003e0.02\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd style=\\\"width: 29.3204%;\\\"\\u003e\\n \\u003cp\\u003eCoil length (cm), mean (SD)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 20.1942%;\\\"\\u003e\\n \\u003cp\\u003e10 (4.4)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 20.1942%;\\\"\\u003e\\n \\u003cp\\u003e15 (11.6)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 5.53398%;\\\"\\u003e\\n \\u003cp\\u003e0.52\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 19.2233%;\\\"\\u003e\\n \\u003cp\\u003e11 (5.4)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 5.53398%;\\\"\\u003e\\n \\u003cp\\u003e0.07\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd style=\\\"width: 29.3204%;\\\"\\u003e\\n \\u003cp\\u003eSecondary coil diameter (mm), mean (SD)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 20.1942%;\\\"\\u003e\\n \\u003cp\\u003e3.0 (0.9)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 20.1942%;\\\"\\u003e\\n \\u003cp\\u003e4.6 (2.9)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 5.53398%;\\\"\\u003e\\n \\u003cp\\u003e0.73\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 19.2233%;\\\"\\u003e\\n \\u003cp\\u003e3.3 (1.1)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 5.53398%;\\\"\\u003e\\n \\u003cp\\u003e0.27\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd style=\\\"width: 29.3204%;\\\"\\u003e\\n \\u003cp\\u003ePrimary coil diameter \\u0026le; 0.012 inch, n (%)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 20.1942%;\\\"\\u003e\\n \\u003cp\\u003e9 (32.1)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 20.1942%;\\\"\\u003e\\n \\u003cp\\u003e27 (6.4)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 5.53398%;\\\"\\u003e\\n \\u003cp\\u003e0.94\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 19.2233%;\\\"\\u003e\\n \\u003cp\\u003e32 (52.5)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 5.53398%;\\\"\\u003e\\n \\u003cp\\u003e0.45\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd style=\\\"width: 29.3204%;\\\"\\u003e\\n \\u003cp\\u003eBranches; \\u0026ge;4th-order branch, n (%)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 20.1942%;\\\"\\u003e\\n \\u003cp\\u003e6 (21.4)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 20.1942%;\\\"\\u003e\\n \\u003cp\\u003e35 (8.3)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 5.53398%;\\\"\\u003e\\n \\u003cp\\u003e-0.78\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 19.2233%;\\\"\\u003e\\n \\u003cp\\u003e36 (59.0)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 5.53398%;\\\"\\u003e\\n \\u003cp\\u003e0.18\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003c/tbody\\u003e\\n\\u003c/table\\u003e\\n\\u003cp\\u003eCharacteristics are presented at the patient and branch-coil combination (BCC) levels. Patient numbers are listed alongside BCCs to clarify the scale of analysis. Standardized mean differences (SMDs) evaluate the balance between success and failure groups before and after propensity score matching.\\u003cstrong\\u003e\\u0026nbsp;\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eTable 2. Logistic Regression Results for Catheter Configuration and Tortuosity Variables\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003ctable border=\\\"0\\\" cellspacing=\\\"0\\\" cellpadding=\\\"0\\\" align=\\\"\\\" width=\\\"879\\\"\\u003e\\n \\u003ctbody\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd style=\\\"width: 20.7289%;\\\"\\u003e\\u003cbr\\u003e\\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 12.1868%;\\\"\\u003e\\n \\u003cp\\u003e\\u003cstrong\\u003eFailure\\u0026nbsp;\\u003c/strong\\u003e\\u003c/p\\u003e\\n \\u003cp\\u003e\\u003cstrong\\u003e\\u0026nbsp;n (%)\\u003c/strong\\u003e\\u003c/p\\u003e\\n \\u003cp\\u003e\\u003cstrong\\u003eN = 28\\u003c/strong\\u003e\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 12.1868%;\\\"\\u003e\\n \\u003cp\\u003e\\u003cstrong\\u003eSuccess\\u003c/strong\\u003e\\u003c/p\\u003e\\n \\u003cp\\u003e\\u003cstrong\\u003e\\u0026nbsp;n (%)\\u003c/strong\\u003e\\u003c/p\\u003e\\n \\u003cp\\u003e\\u003cstrong\\u003eN = 61\\u003c/strong\\u003e\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 19.3622%;\\\"\\u003e\\n \\u003cp\\u003e\\u003cstrong\\u003eUnivariable p-value\\u003c/strong\\u003e\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 19.3622%;\\\"\\u003e\\n \\u003cp\\u003e\\u003cstrong\\u003eMultivariable p-value\\u003c/strong\\u003e\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 16.1731%;\\\"\\u003e\\n \\u003cp\\u003e\\u003cstrong\\u003eOR (95% CI)\\u003c/strong\\u003e\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd style=\\\"width: 20.7289%;\\\"\\u003e\\n \\u003cp\\u003eIntercept\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 12.1868%;\\\"\\u003e\\n \\u003cp\\u003e-\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 12.1868%;\\\"\\u003e\\n \\u003cp\\u003e-\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 19.3622%;\\\"\\u003e\\n \\u003cp\\u003e-\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 19.3622%;\\\"\\u003e\\n \\u003cp\\u003e0.001\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 16.1731%;\\\"\\u003e\\n \\u003cp\\u003e0.04 (0.005-0.25)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd style=\\\"width: 20.7289%;\\\"\\u003e\\n \\u003cp\\u003eProx 90-180\\u0026deg; Inv.\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 12.1868%;\\\"\\u003e\\n \\u003cp\\u003e17 (60.7%)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 12.1868%;\\\"\\u003e\\n \\u003cp\\u003e19 (31.1%)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 19.3622%;\\\"\\u003e\\n \\u003cp\\u003e0.01\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 19.3622%;\\\"\\u003e\\n \\u003cp\\u003e0.03\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 16.1731%;\\\"\\u003e\\n \\u003cp\\u003e4.5 (1.1-18)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd style=\\\"width: 20.7289%;\\\"\\u003e\\n \\u003cp\\u003eTip 90\\u0026ndash;180\\u0026deg; Inv.\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 12.1868%;\\\"\\u003e\\n \\u003cp\\u003e21 (75.0%)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 12.1868%;\\\"\\u003e\\n \\u003cp\\u003e6 (10.0%)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 19.3622%;\\\"\\u003e\\n \\u003cp\\u003e\\u0026lt;0.0001\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 19.3622%;\\\"\\u003e\\n \\u003cp\\u003e0.008\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 16.1731%;\\\"\\u003e\\n \\u003cp\\u003e22 (2.2-220)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd style=\\\"width: 20.7289%;\\\"\\u003e\\n \\u003cp\\u003eS-Shape\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 12.1868%;\\\"\\u003e\\n \\u003cp\\u003e15 (53.6%)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 12.1868%;\\\"\\u003e\\n \\u003cp\\u003e3 (5.0%)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 19.3622%;\\\"\\u003e\\n \\u003cp\\u003e\\u0026lt;0.0001\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 19.3622%;\\\"\\u003e\\n \\u003cp\\u003e0.36\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 16.1731%;\\\"\\u003e\\n \\u003cp\\u003e2.6 (0.3-20)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd style=\\\"width: 20.7289%;\\\"\\u003e\\n \\u003cp\\u003eQT, mean (SD)\\u0026nbsp;\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 12.1868%;\\\"\\u003e\\n \\u003cp\\u003e1.8 (0.9)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 12.1868%;\\\"\\u003e\\n \\u003cp\\u003e1.2 (0.5)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 19.3622%;\\\"\\u003e\\n \\u003cp\\u003e\\u0026lt;0.0001\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 19.3622%;\\\"\\u003e\\n \\u003cp\\u003e0.55\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 16.1731%;\\\"\\u003e\\n \\u003cp\\u003e0.7 (0.2-2.1)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd style=\\\"width: 20.7289%;\\\"\\u003e\\n \\u003cp\\u003eCoil Mismatch\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 12.1868%;\\\"\\u003e\\n \\u003cp\\u003e21 (75.0%)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 12.1868%;\\\"\\u003e\\n \\u003cp\\u003e27 (44.3%)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 19.3622%;\\\"\\u003e\\n \\u003cp\\u003e0.01\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 19.3622%;\\\"\\u003e\\n \\u003cp\\u003e0.03\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 16.1731%;\\\"\\u003e\\n \\u003cp\\u003e4.9 (1.2-21)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003c/tbody\\u003e\\n\\u003c/table\\u003e\\n\\u003cp\\u003e\\u0026nbsp;Prox 90\\u0026ndash;180\\u0026deg; Inv. = 90\\u0026ndash;180\\u0026deg; inversion in the proximal portion of the catheter (excluding the tip); Tip 90\\u0026ndash;180\\u0026deg; Inv. = 90\\u0026ndash;180\\u0026deg; inversion of the distal 2 cm of the catheter tip; S-Shape = S-shaped configuration; Coil Mismatch = Catheter inner diameter\\u0026ndash;coil primary diameter mismatch; QT = Quantitative Tortuosity. Univariate p-values were obtained by Fisher\\u0026rsquo;s exact test (categorical variables) or t-test / Mann\\u0026ndash;Whitney U test (continuous variables). Multivariate p-values, odds ratios (OR), and 95% confidence intervals (CI) were derived from the generalized linear mixed model (GLMM) logistic regression.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eTable 3. Management Strategies for 28 Failed Branch\\u0026ndash;Detachable Coil Combinations\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003ctable border=\\\"0\\\" cellspacing=\\\"0\\\" cellpadding=\\\"0\\\" width=\\\"1020\\\"\\u003e\\n \\u003ctbody\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd style=\\\"width: 358px;\\\"\\u003e\\n \\u003cp\\u003e\\u003cstrong\\u003eMismatch Category\\u003c/strong\\u003e\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 142px;\\\"\\u003e\\n \\u003cp\\u003e\\u003cstrong\\u003eRCM\\u003c/strong\\u003e\\u003c/p\\u003e\\n \\u003cp\\u003e\\u003cstrong\\u003e\\u0026nbsp;(n = 16), n (%)\\u003c/strong\\u003e\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 217px;\\\"\\u003e\\n \\u003cp\\u003e\\u003cstrong\\u003eCatheter repositioning or alternate coil (n = 6), n (%)\\u003c/strong\\u003e\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 208px;\\\"\\u003e\\n \\u003cp\\u003e\\u003cstrong\\u003eThinner or More Flexible Coil (n = 6), n (%)\\u003c/strong\\u003e\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 94px;\\\"\\u003e\\n \\u003cp\\u003e\\u003cstrong\\u003e\\u003cem\\u003eP\\u003c/em\\u003e\\u003c/strong\\u003e\\u003cstrong\\u003e-value\\u003c/strong\\u003e\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd style=\\\"width: 358px;\\\"\\u003e\\n \\u003cp\\u003eMicrocatheter-detachable coil mismatch (n =21)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 142px;\\\"\\u003e\\n \\u003cp\\u003e16/16 (100%)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 217px;\\\"\\u003e\\n \\u003cp\\u003e5/6 (83.3%)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 208px;\\\"\\u003e\\n \\u003cp\\u003e0/6 (0%)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd rowspan=\\\"2\\\" style=\\\"width: 94px;\\\"\\u003e\\n \\u003cp\\u003e\\u0026lt;0.0001\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd style=\\\"width: 358px;\\\"\\u003e\\n \\u003cp\\u003eProper-microcatheter-detachable coil match (n=7)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 142px;\\\"\\u003e\\n \\u003cp\\u003e0/16 (0%)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 217px;\\\"\\u003e\\n \\u003cp\\u003e1/6 (16.7%)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 208px;\\\"\\u003e\\n \\u003cp\\u003e6/6 (100%)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003c/tbody\\u003e\\n\\u003c/table\\u003e\\n\\u003cp\\u003eRCM = Resolution of microcatheter\\u0026ndash;detachable coil mismatch; Catheter Repositioning or Alternate Coil = Microcatheter repositioning to avoid kinking or selection of a different coil gauge/length; Thinner or More Flexible Coil = Use of a coil with thinner strands or greater flexibility\\u003c/p\\u003e\"}],\"fulltextSource\":\"\",\"fullText\":\"\",\"funders\":[],\"hasAdminPriorityOnWorkflow\":false,\"hasManuscriptDocX\":true,\"hasOptedInToPreprint\":true,\"hasPassedJournalQc\":\"\",\"hasAnyPriority\":false,\"hideJournal\":true,\"highlight\":\"\",\"institution\":\"\",\"isAcceptedByJournal\":false,\"isAuthorSuppliedPdf\":false,\"isDeskRejected\":\"\",\"isHiddenFromSearch\":false,\"isInQc\":false,\"isInWorkflow\":false,\"isPdf\":false,\"isPdfUpToDate\":true,\"isWithdrawnOrRetracted\":false,\"journal\":{\"display\":true,\"email\":\"info@researchsquare.com\",\"identity\":\"researchsquare\",\"isNatureJournal\":false,\"hasQc\":true,\"allowDirectSubmit\":true,\"externalIdentity\":\"\",\"sideBox\":\"\",\"snPcode\":\"\",\"submissionUrl\":\"/submission\",\"title\":\"Research Square\",\"twitterHandle\":\"researchsquare\",\"acdcEnabled\":true,\"dfaEnabled\":false,\"editorialSystem\":\"\",\"reportingPortfolio\":\"\",\"inReviewEnabled\":false,\"inReviewRevisionsEnabled\":true},\"keywords\":\"Detachable coil embolization, Vascular curvature, Microcatheter–detachable coil mismatch, Coil flexibility\",\"lastPublishedDoi\":\"10.21203/rs.3.rs-6256551/v1\",\"lastPublishedDoiUrl\":\"https://doi.org/10.21203/rs.3.rs-6256551/v1\",\"license\":{\"name\":\"CC BY 4.0\",\"url\":\"https://creativecommons.org/licenses/by/4.0/\"},\"manuscriptAbstract\":\"\\u003cp\\u003e\\u003cstrong\\u003ePurpose: \\u003c/strong\\u003eThis study examined whether sharp vessel angulation (≥90–180°) and microcatheter–detachable coil compatibility independently increase coil maldelivery in non-neuro arterial embolization, and how these factors affect technical failure and salvage strategies.\\u003cstrong\\u003e\\u0026nbsp;\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eMaterials and Methods: \\u003c/strong\\u003eA single-center, IRB-approved analysis from February 2023 to December 2024 included 451 arterial branch–detachable coil combinations (BCCs) in 119 patients (mean age 64 years, range 32–87). Angulations of 90–180° at the proximal catheter segment and distal tip were evaluated on digital subtraction angiography. Technical failure was defined as inability to deploy the coil as intended, including unraveling or coil shape distortion. A 1:3 propensity score matching (28 failed vs 61 successful BCCs) balanced coil features and target-vessel factors. Mismatch was recorded if coil primary diameter exceeded or fell below microcatheter thresholds. A generalized linear mixed model accounted for within-patient clustering.\\u003cstrong\\u003e\\u0026nbsp;\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eResults: \\u003c/strong\\u003eCoil failure occurred in 28 of 451 BCCs (6.2 %). A 90–180° inversion at the catheter tip (odds ratio [OR], 22; p = 0.008) and mismatch (OR, 4.9; p = 0.03) independently predicted failure. A proximal 90–180° inversion also contributed (OR, 4.5; p = 0.03). Of 28 failures, 21/28 (75%) were mismatched: 16/21 (76%) resolved via mismatch correction, and 5/21 (24%) required repositioning or an alternate coil gauge/length. Proper-match failures (n=7) were treated with thinner or more flexible coils in 6 (85.7%; p \\u0026lt; 0.0001).\\u0026nbsp;\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eConclusions: \\u003c/strong\\u003eSharp vessel angulation (≥90–180°) and microcatheter–coil mismatch each heighten maldelivery risk. Repositioning or adjusting coil dimensions can salvage mismatched cases, whereas more flexible coils help in matched cases.\\u003c/p\\u003e\",\"manuscriptTitle\":\"Vessel Curvature and Microcatheter–Detachable Coil Compatibility in Arterial Coil Embolization\",\"msid\":\"\",\"msnumber\":\"\",\"nonDraftVersions\":[{\"code\":1,\"date\":\"2025-04-03 06:22:55\",\"doi\":\"10.21203/rs.3.rs-6256551/v1\",\"editorialEvents\":[{\"type\":\"communityComments\",\"content\":0}],\"status\":\"published\",\"journal\":{\"display\":true,\"email\":\"info@researchsquare.com\",\"identity\":\"researchsquare\",\"isNatureJournal\":false,\"hasQc\":true,\"allowDirectSubmit\":true,\"externalIdentity\":\"\",\"sideBox\":\"\",\"snPcode\":\"\",\"submissionUrl\":\"/submission\",\"title\":\"Research Square\",\"twitterHandle\":\"researchsquare\",\"acdcEnabled\":true,\"dfaEnabled\":false,\"editorialSystem\":\"\",\"reportingPortfolio\":\"\",\"inReviewEnabled\":false,\"inReviewRevisionsEnabled\":true}}],\"origin\":\"\",\"ownerIdentity\":\"0e1d6fe7-e27b-4e6e-9d34-88e8ba922d94\",\"owner\":[],\"postedDate\":\"April 3rd, 2025\",\"published\":true,\"recentEditorialEvents\":[],\"rejectedJournal\":[],\"revision\":\"\",\"amendment\":\"\",\"status\":\"posted\",\"subjectAreas\":[],\"tags\":[],\"updatedAt\":\"2025-04-10T11:13:25+00:00\",\"versionOfRecord\":[],\"versionCreatedAt\":\"2025-04-03 06:22:55\",\"video\":\"\",\"vorDoi\":\"\",\"vorDoiUrl\":\"\",\"workflowStages\":[]},\"version\":\"v1\",\"identity\":\"rs-6256551\",\"journalConfig\":\"researchsquare\"},\"__N_SSP\":true},\"page\":\"/article/[identity]/[[...version]]\",\"query\":{\"redirect\":\"/article/rs-6256551\",\"identity\":\"rs-6256551\",\"version\":[\"v1\"]},\"buildId\":\"8U1c8b4HqxoKbykW_rLl7\",\"isFallback\":false,\"isExperimentalCompile\":false,\"dynamicIds\":[84888],\"gssp\":true,\"scriptLoader\":[]}","source_license":"CC-BY-4.0","license_restricted":false}