Coil Packing Density Research Articles

Volume measurement of the intracranial aneurysm: a discussion and comparison of the alternatives to manual segmentation.

ObjectiveSeveral modalities are available for volumetric measurement of the intracranial aneurysm. We discuss the challenges involved in manual segmentation, and analyze the application of alternative methods using automatic segmentation and geometric formulae in measurement of aneurysm volumes and coil packing density.MethodsThe volumes and morphology of 38 aneurysms treated with endovascular coiling at a single center were measured using three-dimensional rotational angiography (3DRA) reconstruction software using automatic segmentation. Aneurysm volumes were also calculated from their height, width, depth, size of neck, and assumed shape in 3DRA images using simple geometric formulae. The aneurysm volumes were dichotomized as "small" or "large" using the median volume of the studied population (54 mm3) measured by automatic segmentation as the cut-off value for further statistical analysis.ResultsA greater proportion of aneurysms were categorized as being "small" when geometric formulae were applied. The median aneurysm volumes obtained were 54.5 mm3 by 3DRA software, and 30.6 mm3 using mathematical equations. An underestimation of aneurysm volume with a resultant overestimation in the calculated coil packing density (p = 0.002) was observed.ConclusionCaution must be exercised in the application of simple geometric formulae in the management of intracranial aneurysms as volumes may potentially be underestimated and packing densities falsely elevated. Future research should focus on validation of automatic segmentation in volumetric measurement and improving its accuracy to enhance its application in clinical practice.

Finite element modeling of embolic coil deployment: Multifactor characterization of treatment effects on cerebral aneurysm hemodynamics

Endovascular coiling is the most common treatment for cerebral aneurysms. During the treatment, a sequence of embolic coils with different stiffness, shapes, sizes, and lengths is deployed to fill the aneurysmal sac. Although coil packing density has been clinically correlated with treatment success, many studies have also reported success at low packing densities, as well as recurrence at high packing densities. Such reports indicate that other factors may influence treatment success. In this study, we used a novel finite element approach and computational fluid dynamics (CFD) to investigate the effects of packing density, coil shape, aneurysmal neck size, and parent vessel flow rate on aneurysmal hemodynamics. The study examines a testbed of 80 unique CFD simulations of post-treatment flows in idealized basilar tip aneurysm models. Simulated coil deployments were validated against in vitro and in vivo deployments. Among the investigated factors, packing density had the largest effect on intra-aneurysmal velocities. However, multifactor analysis of variance showed that coil shape can also have considerable effects, depending on packing density and neck size. Further, linear regression analysis showed an inverse relationship between mean void diameter in the aneurysm and mean intra-aneurysmal velocities, which underscores the importance of coil distribution and thus coil shape. Our study suggests that while packing density plays a key role in determining post-treatment hemodynamics, other factors such as coil shape, aneurysmal geometry, and parent vessel flow may also be very important.

O-017 Preliminary Experience with a New Barrel Shaped Bifurcation Aneurysm Bridging Device

PurposeTo test the feasibility of a novel fully retrievable barrel-shaped vascular reconstruction device for stent assisted endovascular treatment of wide-necked bifurcation aneurysms.Methods16 Canine were utilised to assess the acute technical...

Abstract WP76: Investigation of the Influence of Coil Configuration on Cerebral Aneurysm Fluid Dynamics Using a Novel Finite Element Approach

INTRODUCTION: Despite more than a decade of endovascular coil treatment, the effects of coils on cerebral aneurysm (CA) hemodynamics are still poorly understood. Coils present several challenges to in vivo and in vitro flow measurement techniques and previous in silico methods have suffered from large assumptions on coil geometry. Here we present the first fluid dynamic simulations of coiled CAs that consider the structure and deployment mechanics of embolic coils. We also investigate the influence of coil packing density, design, and configuration on CA fluid dynamics. Methods: Coil deployment was modeled using a novel finite element approach that realistically simulates coil dynamics during deployment. Two coil designs were investigated: helical and 3D. Coil design and material properties were matched to manufacturer specifications. Five deployment sequences of each coil design, at different microcatheter placements, were simulated in two idealized CA models with variable neck sizes. Blood flow was simulated using computational fluid dynamics. Simulated deployments and fluid dynamics were then compared to deployments of actual coils in identical physical CA models and in vitro particle image velocimetry flow measurements. Results: Simulated results closely matched in vitro data. Reductions in aneurysmal velocity magnitudes were largest for 3D coils and in a narrow-neck model. In that model, 3D coil deployments reduced average aneurysmal velocity magnitudes by a 51% - 69% range at packing densities less than 20% and by a 74% - 84% range at packing densities greater than 30%. Linear regression results showed reductions were strongly dependent on the spacing between coil loops within the aneurysm and packing density, with correlations of 0.6 and 0.7 respectively. Conclusion: Coil design and packing density may play equally important roles in determining CA hemodynamics. Results in an anatomical model will also be presented. The proposed virtual coiling approach represents a novel and effective method for realistically simulating coiled CAs, and is an important step towards clinical preoperative planning of coil treatment.

Results of endovascular treatment of aneurysms depending on their size, volume and coil packing density

Background and purposeIn contrast to neurosurgery, which is more efficient, endovascular treatment (EVT) is less invasive. The main purpose of EVT is complete occlusion of the aneurysm and protection from subarachnoid haemorrhage. Accurate measurements of the aneurysm (size, volume) obtained using a 3D digital subtraction angiography (DSA) workstation can assist in the proper assessment of coil packing density (CPD), which affects possible distant recanalization. The main disadvantage of endovascular treatment of intracranial aneurysms compared to neurosurgery is the high recurrence rate. We evaluated the results of endovascular treatment of aneurysms depending on their size, volume and coil packing density. Material and methodsThirty-five patients with intracranial aneurysms underwent endovascular embolization with bare platinum coils. Three-dimensional DSA was used to evaluate aneurysms’ morphology. Eighteen patients underwent 3D DSA follow-up 6-45 months after treatment. Initial and follow-up results of embolization were assessed with the Raymond-Montreal scale. The impact of aneurysms’ morphology, volume and initial CPD on endovascular treatment was evaluated. ResultsAmong 35 patients, complete initial embolization was achieved in 74%. Mean initial aneurysm volume in 3D DSA was 0.517 mL and decreased significantly after embolization. Initial CPD varied from 74% to 2% depending on aneurysm diameter (12.1% for aneurysms ≥ 10 mm, 22.5% for aneurysms < 10 mm). Results of embolization on the Raymond-Montreal scale significantly depended on aneurysms’ CPD. Aneurysms’ recanalization rate on 3D DSA follow-up was 36%, with complete recanalization in 3.3%. ConclusionsWe can achieve a better outcome if size and volume of the aneurysm sac is smaller and if CPD is higher.

Stent usage in the treatment of intracranial aneurysms: past, present and future

As endovascular approaches to intracranial aneurysm (IA) treatment continue to evolve, the use of intracranial stents has advanced from an infrequent adjunct to potential curative monotherapy. Early results of endovascular...

Impact of different coil packing densities on intra-aneurysmal hemodynamics during embolization of intracranial aneurysm: a numerical simulative study

Objective To investigate the impact of different coil packing densities on intra-secular hemodynamics during embolization of intracranial aneurysm,so as to provide the theoretical evidence for endovascular treatment of intracranical aneurysms.Methods Based on digital subtraction angiography image data,the vessel numerical models with different packing densities were constructed using computational fluid dynamics software.The hemodynamic parameters,including the wall shear stress(WSS) and flow steamline and pressure,were obtained from the numerical simulation using Ansys CFX software.Results The aneurysm volume and low WSS area in the aneurysm sac were decreased after the first session of embolization compared with before treatment;the vortex in the aneurysm was decreased and the aneurysmal flow velocity had no significant changes.Meanwhile,the WSS at the aneurysm dome increased to 2.13 Pa.Continuous embolization greatly decreased the overall aneurysmal flow velocity and the aneurysmal flow velocity at the distal part of the residual aneurysm neck.The average wall pressure of the inflow tract had no noticeable changes before and after embolization.Conclusion The intra-saccular hemodynamics during embolization of intracranial aneurysm can be influenced by the coil packing density and coil distribution in the aneurysm.

How Do Coil Configuration and Packing Density Influence Intra-Aneurysmal Hemodynamics?

Endovascular coiling is a well-established therapy for treating intracranial aneurysms. Nonetheless, postoperative hemodynamic changes induced by this therapy remain not fully understood. The purpose of this work is to assess the influence of coil configuration and packing density on intra-aneurysmal hemodynamics. Three 3D rotational angiography images of 3 intracranial aneurysms before and after endovascular coiling were used. For each aneurysm, a 3D representation of the vasculature was obtained after the segmentation of the images. Afterward, a virtual coiling technique was used to treat the aneurysm geometries with coil models. The aneurysms were coiled with 5 packing densities, and each was generated by using 3 coil configurations. Computational fluid dynamics analyses were carried out in both untreated and treated aneurysm geometries. Statistical tests were performed to evaluate the relative effect of coil configuration on local hemodynamics. The intra-aneurysmal blood flow velocity and wall shear stress were diminished as packing density increased. Aneurysmal flow velocity was reduced >50% due to the first inserted coils (packing density <12%) but with a high dependency on coil configuration. Nonsignificant differences (P > .01) were found in the hemodynamics due to coil configuration for high packing densities (near 30%). A damping effect was observed on the intra-aneurysmal blood flow waveform after coiling. Intra-aneurysmal hemodynamics are altered by coils. Coil configuration might reduce its influence on intra-aneurysmal hemodynamics as the packing density increases until an insignificant influence could be achieved for high packing densities.

A single center comparison of coiling versus stent assisted coiling in 90 consecutive paraophthalmic region aneurysms

IntroductionAneurysm recurrence is a principle limitation of endovascular coiling procedures, with recurrence rates reported of >30%. The adjunct use of self-expandable stents has revolutionized the treatment of intracranial aneurysms, especially...

Embolization of intracranial aneurysms with second-generation Matrix-2 detachable coils: mid-term and long-term results

BackgroundBioactive polyglycolic/polylactic acid (PGLA)-coated Matrix detachable coils were reported to incite intra-aneurysmal inflammation and fibrosis. Multiple large case series with Matrix-1 coils have shown no advantage with respect to aneurysm...

P-015 Mid term and long term results with second generation Matrix2 detachable coils

PurposeBioactive polyglycolic/polylactic acid coated matrix detachable coils (Boston Scientific, Natick, Massachusetts, USA) were reported to incite intra-aneurysmal inflammation and fibrosis. Multiple large case series have shown no significant advantage with...

Quantitative Effects of Coil Packing Density on Cerebral Aneurysm Fluid Dynamics: An In Vitro Steady Flow Study

Over the past 15 years, coil embolization has emerged as an effective treatment option for cerebral aneurysms that is far less invasive than the long-standing convention of surgical clipping. However, aneurysm recurrence after coil embolization is not uncommon: recurrence rates as high as 50% have been reported in the literature. One factor that may contribute to recurrence after coiling is residual flow into the aneurysmal sac. At present, there is limited quantitative knowledge of the relationship between coil packing density and aneurysmal inflow. We present an in vitro fluid dynamic study of basilar tip aneurysm models that elucidates this relationship. At physiologically normal flow rates, we found that a packing density of 28.4% decreased aneurysmal inflow by 31.6% in a wide-neck model, and that a packing density of 36.5% decreased aneurysmal inflow by 49.6% in a narrow-neck model. Results also indicated that coiling reduced aneurysmal inflow more significantly at lower parent vessel flow rates, and that coiling reduced neck-plane velocity magnitudes more significantly for narrow-neck aneurysms. Our study provides novel quantitative information that could ultimately contribute to improved outcomes for patients with cerebral aneurysms by enabling more effective coil embolization.

005 DeltaPaq coils in the treatment of intracranial aneurysms: packing density, clinical and angiographic results

Purpose: Recanalization of the aneurysm sac is a major drawback of endovascular embolization that often necessitates retreatment. Recent evidence suggests that increased packing density of coils within the aneurysm sac...

Embolization of Cerebral Aneurysms with Spherically Shaped Detachable Microcoils (MicruSphere Microcoil System)

We present our initial experience of concentric-filling technique using MicruSphere 3D coils (Micrus Endovascular, San Jose, CA) in the treatment of intracranial aneurysms. 149 intracranial saccular aneurysms in 142 consecutive patients (mean age 56.6-/+12.7, ruptured in 54 (36.2%)) were treated with the concentric-filling technique. The mean aneurysm volume was 169.0-/+363.0 mm(3). Neck remodeling technique was used in 120 (80.5%). Procedure-related problems were recorded. Initial embolization results were evaluated, and the coil packing density was calculated. Clinical and angiographic follow-ups were performed after six months. Any changes in embolization status were classified as 'improved', 'unchanged', or 'worse'. The overall packing density was 40.1% (range 10.5-90.9%). The permanent morbidity and mortality rates were 4.0% and 1.3%, respectively. The initial Raymond and Roy classification results were class 1 in 37 aneurysms (24.8%), class 2 in 50 (33.6%), and class 3 in 62 (41.6%). On the mean follow-up examination of 8.2 months in 103 patients (72.5%), there were one transient ischemic attack, one minor stroke, and one instance of rebleeding. Angiographic follow-up in 101 aneurysms (67.8%) showed the change in embolization status as 'improved' in 42 aneurysms (41.6%), 'unchanged' in 42 (41.6%), and 'worse' in 17 (recanalisation rate, 16.8%). The concentric-filling technique using Micrusphere 3D coils was effective in achieving high packing density which in turn resulted in stable embolization in the majority of the aneurysms. Longer follow-up is warranted to determine the durability of these results.

Endovascular management of a ruptured cavernous carotid artery aneurysm associated with a carotid cavernous fistula with an intracranial self-expanding microstent and hydrogel-coated coil embolization: case report and review of the literature

Background Ruptured CCAs are traditionally treated with endovascular management. Advances in microstent and coil technology have allowed improved intracranial navigation, increased coil packing density, and coil volume expansion to facilitate complete coil embolization of aneurysms/fistulae. We report a case of a ruptured CCA with an associated CCF treated with an intracranial, self-expanding microstent in combination with coil embolization using hydrogel-coated platinum coils. Case Description A 50-year-old woman presented with a 7-day history of severe headache and 2 days of progressive left-sided ptosis, ophthalmoplegia, and facial dysesthesias. A cerebral angiogram demonstrated a left ruptured wide-necked CCA with an associated CCF. An intracranial, self-expanding microstent (Neuroform 3, Boston Scientific, Natick, MA) was placed across the aneurysmal neck. The aneurysm was subsequently embolized with hydrogel-coated platinum coils (Hydro Coil). A 3-month follow-up angiogram showed complete resolution of arteriovenous shunting with near-complete occlusion of the CCA. The patient's ocular pain and facial dysesthesias resolved completely, with near-complete resolution of ophthalmoplegia. Conclusions This case demonstrates near-complete occlusion of a ruptured CCA and obliteration of an associated CCF using endovascular combinational therapy of an intracranial, self-expanding microstent with hydrogel-coated platinum coils. Use of this newer-generation stent-coil combination may allow more complete and durable lesion occlusion because of increased coil packing density and coil volume expansion without the need for parent artery sacrifice or balloon-remodeling techniques, thus avoiding the potential complications of such therapies.

Scale invariance of the density fluctuations in films and macromolecular aggregates in poly(styrene) solutions

The specific features of the transformation of a polymer solution into a solid state (film) of an amorphous polymer are investigated using electron microscopy. The correspondence between the characteristics of fractal macromolecular aggregates in a solution and the parameters of the spatial distribution of density fluctuations at the surface of the film is established using a linear atactic poly(styrene) as an example. The correspondence exists under the condition that the packing density of coils does not exceed a critical value at the liquid-solid phase transition point and the polymer concentration in the solution provides the formation of a continuous network of entangled macromolecules.

Endovascular treatment of intracranial aneurysms with matrix coils: immediate posttreatment results, clinical outcome and follow-up

Endovascular aneurysm repair with coils has become a safe and effective alternative to surgical clipping. Efforts have been made to create coils that will facilitate aneurysm healing and reduce recurrence. The purpose of this study was to review the safety and durability of our aneurysm treatment using Matrix coils. A total of 39 aneurysms in 38 patients, aged 30 to 77 years, were treated using Matrix coils in 42 procedures. Two procedures were unsuccessful, and 12 were done using only Matrix coils. Aneurysm volume, packing density and percentage length of Matrix coils were calculated. The treatment results, procedural complication rate and clinical outcome were analyzed. Follow-up examinations were available for 34 procedures with a mean follow-up of 4.9 months (maximum 13.5 months). Angiographic results were similar to those following the use of platinum coils, with complete occlusion or a residual neck in 82.5% of procedures. Six procedures (14%) were complicated with platelet aggregation. Recanalization occurred in 32% of the patients. Nine patients (26%) had major recanalization and were retreated. One patient had a re-bleed 5 months after the treatment resulting in severe disability. The mean packing density of 39.2% in the recanalized aneurysms was similar to that in the nonrecanalized group. In our series, treatment with Matrix coils had a complication rate similar to that reported with platinum coils. However, we had a higher percentage of major recanalizations requiring retreatment. We believe that the absorption of the polymer contributes to the failure of formation of a stable scar within the aneurysm.

Balloon assistance as a routine adjunct to the endovascular treatment of cerebral aneurysms

Background The technique of BAC is attractive because the balloon theoretically allows for (1) “control” of blood flow in the vessel; (2) improved stability of the microcatheter in the aneurysm; (3) denser packing with coils; and (4) improved delineation of the neck of the aneurysm. The purpose of this communication is to document our outcomes with this technique and help determine if this technique is of benefit. Methods Data on all endovascularily treated aneurysms have been gathered prospectively at our institution since March 2000. The first case of BAC was in November 2000. We have become very liberal in our indications, to the point where all aneurysms are considered for BAC. We document here our results obtained over a 1-year period, during which we treated 56 patients with 60 aneurysms in 58 coiling sessions using only bare platinum coils. Results Balloon-assisted coiling was attempted in 50 (86%) of the 58 coiling sessions. Successful embolizations were achieved in all but 1 patient in whom BAC was attempted. There was one technique-related complication. The packing density for the BAC cases was, on average, 35.7% (median, 34.6%; SD, 14.1%). Follow-up angiography revealed a 13% class 3 recurrence rate. Conclusion With experience, BAC can be used in the endovascular treatment of most cerebral aneurysms. Although complications are associated with its use, we feel that the risk/benefit ratio is favorable. Excellent coil packing density with bare coils is achievable with this technique.

Endovascular Coiling Versus Neurosurgical Clipping for Patients With Aneurysmal Subarachnoid Hemorrhage

Endovascular Coiling Versus Neurosurgical Clipping for Patients With Aneurysmal Subarachnoid Hemorrhage

Endovascular occlusion of intracranial aneurysms with Guglielmi detachable coils: correlation between coil packing density and coil compaction.

This retrospective analysis was undertaken to evaluate a possible relationship between coil packing density and coil compaction on intracranial aneurysms embolized using Guglielmi detachable coils (GDCs). Of the patients who underwent endovascular surgery using GDC in our hospital between 1994 and 1998, 33 patients had endovascular treatment with GDC and were examined by follow-up angiography at least 12 months after surgery. They had coil embolization to the extent where aneurysms were no longer filled or only faintly filled as shown by cerebral angiography immediately after surgery. At follow-up angiography, coil compaction was observed in 3 aneurysms. In all patients with coil compaction, the coil packing density was below 20% (14.5 +/- 4.0%). On the other hand, it was over 20% (25.7 +/- 4.7%) in all patients without coil compaction. In the 11 patients with a basilar bifurcation aneurysm, the coil packing density was over 24% and no coil compaction was observed. The coil packing density seems to be one of the critical factors, particularly for predicting whether or not coil compaction will occur. Endovascular surgery should be performed to obtain coil packing density higher than 20%.