Significance of volume embolization ratio as a predictor of recanalization on endovascular treatment of cerebral aneurysms with guglielmi detachable coils

The white-collar sign after Neuroform Atlas stent-assisted coil embolization of unruptured intracranial aneurysms

PURPOSE

Although stent-assisted technique is expected to help provide a scaffold for neointima formation at the orifice of the aneurysm, not all aneurysms treated with stent-assisted technique develop complete neointima formation. The white-collar sign (WCS) indicates neointimal tissue formation at the aneurysm neck that prevents aneurysm recanalization. The aim of this study was to explore factors related to WCS appearance after stent-assisted coil embolization of unruptured intracranial aneurysms (UIAs).

METHODS

A total of 59 UIAs treated with a Neuroform Atlas stent were retrospectively analyzed. The WCS was identified on digital subtraction angiography (DSA) 1 year after coil embolization. The cohort was divided into WCS-positive and WCS-negative groups, and possible predictors of the WCS were explored using logistic regression analysis.

RESULTS

The WCS appeared in 20 aneurysms (33.9%). In the WCS-positive group, neck size was significantly smaller (4.2 (interquartile range (IQR): 3.8-4.6) versus 5.4 (IQR: 4.2-6.8) mm, p = .006), the VER was significantly higher (31.8% (IQR: 28.6%-38.4%) versus 27.6% (IQR: 23.6%-33.8%), p = .02), and the rate of RROC class 1 immediately after treatment was significantly higher (70% vs 20.5%, p < .001) than in the WCS-negative group. On multivariate analysis, neck size (odds ratio (OR): 0.542, 95% confidence interval (CI): 0.308-0.954; p = .03) and RROC class 1 immediately after treatment (OR: 6.99, 95% CI: 1.769-27.55; p = .006) were independent predictors of WCS appearance.

CONCLUSIONS

Smaller neck size and complete occlusion immediately after treatment were significant factors related to WCS appearance in stent-assisted coil embolization for UIAs using the Neuroform Atlas stent.

Endovascular treatment of intracranial aneurysms: Past and present

Intracranial aneurysm is common in stroke and, once rupturing, will cause disaster to patients. Nowadays, endovascular treatment has become a routine to reduce the risk of intracranial aneurysms rupture. Successive endovascular methods, like balloon-assisted coiling, stent-assisted coiling, and flow diversion, have become new choices for doctors. More and more doctors have been entering this field. Understanding the current general situation is crucial for more medical workers to learn the endovascular treatment of intracranial aneurysms. In the past, many devices and ideas about the treatment of intracranial aneurysms appeared. Although developing unceasingly, endovascular treatment still has some deficiencies to overcome. The advantages and drawbacks of current endovascular methods are discussed.

A novel self-expanding shape memory polymer coil for intracranial aneurysm embolization: 1 year follow-up in Chile

BACKGROUND

Aneurysm recurrence remains a challenge when coiling cerebral aneurysms. Development of next generation coils has focused on accelerating thrombus maturation and increasing coil packing density. Ultra low density shape memory polymer is a novel embolic material designed for this purpose. The polymer is crimped over a platinum-tungsten coil for catheter delivery and self-expands to a predefined volume on contact with blood.

METHODS

This prospective study in humans evaluated aneurysms 5-16 mm (inclusive) in diameter that were indicated for endovascular coil embolization. At least 70% coil volume was required to be shape memory polymer coils. Patients were followed-up according to standard of care for 12 months.

RESULTS

Nine patients (89% women, mean age 55.8±11.7 years) were treated with shape memory polymer coils and completed 12 months of follow-up. Aneurysms were all unruptured and were in the ophthalmic segment of the internal carotid artery (n=7), posterior communicating artery, and anterior cerebral artery A1-A2 segment. Aneurysms were a mean of 7.8±2.9 mm in diameter (range 5.2-14.9 mm). The mean packing density based on unexpanded polymer was 17±6%. Packing density based on expanded polymer was 43±13%. At 12 months, no recurrence had occurred, and a Raymond-Roy occlusion classification of 1 (n=5) or 2 (n=4) was observed. No serious adverse events related to the study device occurred over the 12 months after the procedure.

CONCLUSIONS

Shape memory polymer coils were safe and effective in treating intracranial aneurysms over 12 months in this first study in human subjects.

Volume embolization ratio of coiled cerebral aneurysms, does awake technique affect the results?

Background

Despite the great innovations in the neuroendovascular techniques and related materials, there are still notable percentages of recurrent cerebral aneurysms after aneurysm coiling. Aneurysm packing density is well known to affect the initial angiographic result of aneurysm embolization and has a crucial role in the stability of aneurysm obliteration. Although aneurysm coiling is commonly performed under general anesthesia, it could be performed under local anesthesia in certain circumstances.

Objective

The purpose of this study is to compare the volume embolization ratio (VER) and angiographic results of cerebral aneurysm embolization performed under local and general anesthesia.

Materials and methods

This is a retrospective cohort analysis of 20 consecutive cases of coiled cerebral aneurysms that were coiled under LA. Further, 15 cerebral aneurysm coil embolization cases have been collected from our data as matched control group.

Results

Embolization was performed under local anesthesia (Group A) in 20 patients (57.1%) and under general anesthesia (Group B) in 15 patients (42.9%). At the end of the procedure, control angiogram revealed complete obliteration in 13 patients (37.1%), while incomplete obliteration was detected in 22 patients (62.9%). The mean VER 27.9 ± 11.8 without a significant difference between both groups of the study as the VER of Group (A) was 26.05 ± 8.4 and that of Group B was 30.44 ± 15.2. Follow-up angiography at 1 year revealed complete obliteration in 17 (48.6%) of the coiled aneurysms, while incomplete obliteration was detected in 18 patients (51.4%).

Conclusions

Endovascular coiling of cerebral aneurysms under local anesthesia is a safe and feasible procedure without significant effects on the VER.

Association of circumferential aneurysm wall enhancement with recurrence after coiling of unruptured intracranial aneurysms: a preliminary vessel wall imaging study

OBJECTIVE

Recent histopathological studies of unruptured intracranial aneurysms (UIAs) have confirmed that aneurysm wall enhancement (AWE) on MR vessel wall imaging (VWI) is related to wall degeneration with in vivo inflammatory cell infiltration. Therefore, pretreatment aneurysm wall status on VWI may be associated with recurrence after endovascular treatment.

METHODS

VWI with gadolinium was performed on 67 consecutive saccular UIAs before endovascular treatment between April 2017 and June 2021. The mean (range) follow-up period after treatment was 24.4 (6-54) months. AWE patterns were classified as circumferential AWE (CAWE), focal AWE (FAWE), and negative AWE (NAWE). The authors retrospectively investigated the relationship between aneurysm recurrence and AWE patterns, as well as conventional risk factors.

RESULTS

Sixty-seven patients with 67 saccular UIAs were eligible for the present study. AWE patterns were as follows: 10 CAWE (14.9%), 20 FAWE (29.9%), and 37 NAWE (55.2%). Follow-up MRA detected aneurysm recurrence in 18 of 69 cases (26.1%). Univariate analysis identified maximum diameter (mean ± SD 5.8 ± 2.2 mm in patients with stable aneurysms vs 7.7 ± 3.8 mm in those with unstable aneurysms, p = 0.02), aspect ratio (1.4 ± 0.5 vs 1.1 ± 0.4, p < 0.01), aneurysm location in posterior circulation (4.1% vs 27.8%, p < 0.01), volume embolization ratio (29.6% ± 7.8% vs 25.2% ± 6.1%, p = 0.02), and AWE pattern (p = 0.04) as significant predictive factors of recurrence. Among the 3 AWE patterns, CAWE was significantly more frequent in the unstable group, but no significant differences in stability of the treated aneurysms were observed with the FAWE and NAWE patterns. In multivariate logistic regression analysis, CAWE pattern (OR 14.2, 95% CI 1.8-110.8, p = 0.01) and volume embolization ratio ≥ 25% (OR 8.6, 95% CI 2.1-34.3, p < 0.01) remained as significant factors associated with aneurysm stability after coiling.

CONCLUSIONS

VWI before coiling provides novel insights into the stability of treated aneurysms. Aneurysms with the CAWE pattern on VWI before coiling may be less stable after treatment.

The first coil embolization ratio is the key factor for retreatment for unruptured cerebral aneurysms

Background

In coil embolization, a high volume embolization ratio prevents recanalization that may require retreatment. However, patients with a high volume embolization ratio may also require retreatment. Patients with inadequate framing with the first coil may experience recanalization of the aneurysm. We analyzed the relationship between embolization ratio of the first coil and recanalization requiring retreatment.

Methods

We reviewed data from 181 patients with unruptured cerebral aneurysms who underwent initial coil embolization between 2011 and 2021. We retrospectively analyzed the correlation between neck width, maximum aneurysm size, width, aneurysm volume, volume embolization ratio of the framing coil (first volume embolization ratio [1^st VER]), and final volume embolization ratio (final VER) of cerebral aneurysms in patients and their retreatment.

Results

Recanalization requiring retreatment was observed in 13 patients (7.2%). The factors related to recanalization were neck width, maximum aneurysm size, width, aneurysm volume, and 1^st VER, but not the final VER. Multivariate analysis of the five factors showed a significant difference in the 1^st VER (P = 0.002). The cutoff value for recanalization was a 1^st VER of 5.8%. There were 162 cases with a VER ≥ 20% or higher, and the same analysis yielded similar results.

Conclusion

The 1^st VER was significantly correlated with recanalization of cerebral aneurysms requiring retreatment. In coil embolization of unruptured cerebral aneurysms, it is important to achieve an embolization rate of at least 5.8% using a framing coil to prevent recanalization.

Photosensitive Hydrogel-Based Embolic Agent Treatment of Wide-Necked Aneurysms: Preliminary Animal Results

Background: The endovascular treatment of cerebral aneurysms has become widespread but may still be limited by recurrence rates or complications. The discovery of novel embolic strategies may help mitigate these concerns. Methods: We formulated a Photosensitive Hydrogel Polymer (PHP) embolic agent which is low-viscosity, shear-thinning, and radio-opaque. After the filling of an aneurysm with PHP with balloon assistance, we utilized photopolymerization to induce solidification. Different methods of light delivery for photopolymerization were assessed in silicone models of aneurysms and in four acute animal trials with venous anastomosis aneurysms in pigs. Then, balloon-assisted embolization with PHP and photopolymerization was performed in three aneurysms in pigs with a one-month follow-up. Filling volume, recurrence rates, and complications were recorded. Results: The PHP was found to be suitable for the intravascular delivery and treatment of cerebral aneurysms. It was found that light delivery through the balloon catheter, as opposed to light delivery through the injection microcatheter, led to higher rates of filling in the 3D model and acute animal model for cerebral aneurysms. Using the balloon-assisted embolization and light delivery strategy, three wide-necked aneurysms were treated without complication. One-month follow-up showed no recurrence or neck remnants. Conclusions: We demonstrated a novel method of balloon-assisted photosensitive hydrogel polymer embolization and photopolymerization, leading to complete aneurysm filling with no recurrence at 1 month in three wide-necked aneurysms in pigs. This promising methodology will be investigated further with longer-term comparative animal trials.

Shape Memory Polymer-Based Endovascular Devices: Design Criteria and Future Perspective

Devices for the endovascular embolization of intracranial aneurysms (ICAs) face limitations related to suboptimal rates of lasting complete occlusion. Incomplete occlusion frequently leads to residual flow within the aneurysm sac, which subsequently causes aneurysm recurrence needing surgical re-operation. An emerging method for improving the rates of complete occlusion both immediately after implant and in the longer run can be the fabrication of patient-specific materials for ICA embolization. Shape memory polymers (SMPs) are materials with great potential for this application, owing to their versatile and tunable shape memory properties that can be tailored to a patient’s aneurysm geometry and flow condition. In this review, we first present the state-of-the-art endovascular devices and their limitations in providing long-term complete occlusion. Then, we present methods for the fabrication of SMPs, the most prominent actuation methods for their shape recovery, and the potential of SMPs as endovascular devices for ICA embolization. Although SMPs are a promising alternative for the patient-specific treatment of ICAs, there are still limitations that need to be addressed for their application as an effective coil-free endovascular therapy.

Risk factors for recanalization of dense coil packing for unruptured cerebral aneurysms in endovascular coil embolization: Analysis of a single center's experience

In coil embolization of cerebral aneurysms, inadequate packing is known to increase the probability of recanalization. Even tightly embolized aneurysms may be recanalized, but predictive factors for recanalization have not been fully investigated. This retrospective study aimed to identify risk factors for recanalization of treated aneurysms with a volume embolization ratio (VER) ≥ 25%. A total of 301 unruptured aneurysms in 248 patients who underwent coil embolization between March 2012 and January 2021 were analyzed. Cases involving dissecting aneurysm, intraluminal thrombosis, parent artery occlusion, intraoperative rupture, re-treatment, rupture the day after surgery, postoperative coil migration, and postoperative parent artery occlusion were excluded due to the inaccuracy of VER. A total of 105 aneurysms (34.9%) treated with VER ≥ 25% were extracted. Clinical features (age, sex, medical history, family history), anatomical features (shape, location, aneurysm size, inflow angle, and volume), procedural features (stent-assisted, Raymond-Roy occlusion classification [RROC] immediately after treatment, re-treatment rate), and follow-up period were compared between Recanalization and Non-recanalization groups. Predictors of recanalization were determined using logistic regression and receiver operating characteristic (ROC) curve analyses. Eleven aneurysms were recanalized. In multivariate analysis, RROC class 3 (odds ratio [OR] 11.0; 95% confidence interval [CI] 2.03-59.4) and aneurysm volume (OR 1.005; 95%CI 1.001-1.008) were independent predictors of recanalization. ROC curve analysis showed optimal cutoff values for aneurysm volume of 69.5 mm³ (sensitivity, 81.8%; specificity, 72.3%). In coil embolization of unruptured aneurysms that VER ≥ 25%, cases with RROC class 3 or high aneurysm volume may be associated with a higher risk of recanalization, and should be carefully followed-up.

Optimal Woven EndoBridge (WEB) Device Size Selection Using Automated Volumetric Software

INTRODUCTION

Selecting the appropriate Woven EndoBridge (WEB) device sizing for the treatment of wide-neck bifurcation aneurysms (WNBAs) remains challenging. The aim of this study was to evaluate different volumetric-based imaging methodologies to predict an accurate WEB device size selection to result in a successful implantation.

METHODS

All consecutive patients treated with WEB devices for intracranial aneurysms from January 2019 to June 2020 were included. Aneurysm dimensions to calculate aneurysm volumes were measured using three different modalities: automated three-dimensional (3D) digital subtraction angiography (DSA), manual 3D DSA, and two-dimensional (2D) DSA. The device-aneurysm volume (DAV) ratio was defined as device volume divided by the aneurysm volume. WEB volumes and the DAV ratios were used for assessing the device implantation success and follow-up angiographic outcomes at six months. Pearson correlation, Wilcoxon Rank Sum test, and density approximations were used for estimating the WEB volumes and the imaging modality volumes for successful implantation.

RESULTS

A total of 41 patients with 43 aneurysms were included in the study. WEB device and aneurysm volume correlation coefficient was highest for 3D automatic (r = 0.943), followed by 3D manual (r = 0.919), and 2D DSA (r = 0.882) measurements. Measured median volumes were significantly different for 3D automatic and 2D DSA (p = 0.017). The highest rate of successful implantation (87.5%) was between 0.6 and 0.8 DAV ratio.

CONCLUSION

Pre-procedural assessment of DAV ratios may increase WEB device implantation success. Our results suggest that volumetric measurements, especially using automated 3D volumes of the aneurysms, can assist in accurate WEB device size selection.

Pulsatile Flow-Induced Fatigue-Resistant Photopolymerizable Hydrogels for the Treatment of Intracranial Aneurysms

An alternative intracranial aneurysm embolic agent is emerging in the form of hydrogels due to their ability to be injected in liquid phase and solidify in situ. Hydrogels have the ability to fill an aneurysm sac more completely compared to solid implants such as those used in coil embolization. Recently, the feasibility to implement photopolymerizable poly(ethylene glycol) dimethacrylate (PEGDMA) hydrogels in vitro has been demonstrated for aneurysm application. Nonetheless, the physical and mechanical properties of such hydrogels require further characterization to evaluate their long-term integrity and stability to avoid implant compaction and aneurysm recurrence over time. To that end, molecular weight and polymer content of the hydrogels were tuned to match the elastic modulus and compliance of aneurysmal tissue while minimizing the swelling volume and pressure. The hydrogel precursor was injected and photopolymerized in an in vitro aneurysm model, designed by casting polydimethylsiloxane (PDMS) around 3D printed water-soluble sacrificial molds. The hydrogels were then exposed to a fatigue test under physiological pulsatile flow, inducing a combination of circumferential and shear stresses. The hydrogels withstood 5.5 million cycles and no significant weight loss of the implant was observed nor did the polymerized hydrogel protrude or migrate into the parent artery. Slight surface erosion defects of 2–10 μm in depth were observed after loading compared to 2 μm maximum for non-loaded hydrogels. These results show that our fine-tuned photopolymerized hydrogel is expected to withstand the physiological conditions of an in vivo implant study.

Influence of neurovascular embolic coil primary wind diameter on aneurysm packing density and case costs

AIMS

Endovascular coiling is a common modality for treating intracranial aneurysms; however, recanalization occurs in approximately 1 in 5 cases, with downstream consequences of regrowth and rupture. Aneurysm packing density >24% reduces recanalization risk; packing density can be increased by inserting additional coils or by using coils with larger volumetric filling. Coil volume depends on length and primary wind diameter (PWD). This study evaluated the influence of PWD on packing density and total case costs.

MATERIALS AND METHODS

Two hypothetical scenarios and one case study were analyzed. In scenario one, the number of coils required to achieve packing density >24% in a hypothetical aneurysm was determined for 0.012″ vs. 0.010″ PWD coils. In scenario two, the total length of 0.010″ vs. 0.012″ PWD coils required to achieve a packing density >24% was analyzed relative to aneurysm volume. In the case study, packing densities with one 0.012″ PWD coil (actual scenario) and one 0.010″ PWD coil (theoretical scenario) were compared.

RESULTS

In scenario one, cost savings would be realized by using four 0.012″ PWD coils vs. seven 0.010″ PWD coils to achieve packing density >24%. In scenario two, greater volumetric filling of 0.012″ vs. 0.010″ PWD coils was correlated with lower total length of coil required. In the case study, a 0.012″ PWD coil achieved packing density >24%, whereas an equivalent length 0.010″ PWD coil would not.

LIMITATIONS

Theoretical modeling was used to explore the impact of coil PWD on aneurysm packing density. In clinical practice, packing density depends not only on PWD but on its length, shape, distribution within an aneurysm, and other recanalization risk factors.

CONCLUSIONS

Coil PWD influences packing density, the number of coils required to achieve a specific packing density, and total case costs. Using 0.012″ PWD coils may provide cost and procedural efficiencies.

Initial Experience of Coil Embolization for Unruptured Intracranial Aneurysm Combined with Neuroform Atlas and Undersized Flexible Coils

Objective

Intraprocedural rupture (IPR) is a rare complication that can occur during endovascular treatment (EVT) of unruptured intracranial aneurysms (UIAs). However, it leads to high morbidity and mortality rates. Others have showed that coil flexibility is a risk factor for IPR. Neuroform Atlas (NA) stents can be deployed with 0.0165-inch microcatheters to enable stent assisted coiling (SAC) with a high likelihood. Undersized flexible coils can be inserted initially during SAC. This study aimed to determine whether SAC using NA and highly flexible coils for UIAs can be conducted without IPR.

Methods

We retrospectively analyzed nine consecutive patients (mean age, 73.2 years; female, n = 6) who underwent SAC for UIAs combined with NA stents and undersized flexible coils between January 2017 and December 2019. Two aneurysms were located at the internal carotid artery (ICA), and one each was located at the ICA-posterior communicating, anterior communicating, middle cerebral, vertebral, vertebra-posterior inferior cerebral and basilar arteries. The mean size of the aneurysms was 4.6 (range, 3.1-8.6) mm. SAC proceeded using the jailing technique. All coils were selected from among the most flexible coils available. We retrospectively assessed technical success rates, aneurysm occlusion at final digital subtraction angiography (DSA), volume embolization ratios (VERs), rates of IPR and symptomatic stroke within 30 days, angiographic findings of aneurysm occlusion at 3 months post-procedure and late adverse events (frequency of aneurysmal rupture, ipsilateral ischemic stroke, and retreated targeted aneurysms).

Results

The technical success rate was 100%. Complete occlusion (CO) was immediate in 8 (89%) patients and a neck remnant persisted in 1 (11%). No IPR or symptomatic stroke developed within 30 days. During a mean follow-up period of 11.8 months, CO persisted in 8 (89%) patients. No late adverse events occurred.

Conclusion

The early clinical and angiographic findings of SAC for UIAs combined with an NA stent and undersized flexible coils were favorable for this series.

Initial Raymond-Roy Occlusion Classification but not Packing Density Defines Risk for Recurrence after Aneurysm Coiling

Purpose

After coil embolization of intracranial aneurysms, it is currently not well understood whether the initial coil packing density or the type of aneurysm residual perfusion, depicted by the modified Raymond-Roy occlusion classification, primarily effects the rate of aneurysm recurrence. We hypothesized that these factors interact and only one remains an independent risk factor.

Methods

In this single center retrospective study, 440 patients with intracranial ruptured and unruptured aneurysms between 2010 and 2017 were screened. A total of 267 patients treated with stand-alone coiling, with or without stent or balloon assistance were included (age 54.1 ± 12.2 years, sex 70.4% female). Flow diverter or Woven EndoBridge (WEB) device implantation were exclusion criteria.

Results

Using a binary logistic regression model, independent risk factors for aneurysm recurrence were postinterventional modified Raymond-Roy occlusion classification class (Odds ratio [OR] 1.747, 95% confidence interval [CI] 1.231–2.480) and aneurysm diameter (OR 1.145, CI 1.032–1.271). A trend towards a higher recurrence in ruptured aneurysms did not reach significance (OR 1.656, CI 0.863–3.179). Aneurysm localization, packing density, and neck width were not independently associated with aneurysm recurrence.

Conclusion

Independent risk factors for aneurysm recurrence after coil embolization with and without stent or balloon assistance were aneurysm diameter and postinterventional grading within the modified Raymond-Roy occlusion classification. Packing density interacted with the latter and was not independently associated to recurrence.

Does Increasing Packing Density Using Larger Caliber Coils Improve Angiographic Results of Embolization of Intracranial Aneurysms at 1 Year: A Randomized Trial

BACKGROUND AND PURPOSE

The impact of increased aneurysm packing density on angiographic outcomes has not been studied in a randomized trial. We sought to determine the potential for larger caliber coils to achieve higher packing densities and to improve the angiographic results of embolization of intracranial aneurysms at 1 year.

MATERIALS AND METHODS

Does Embolization with Larger Coils Lead to Better Treatment of Aneurysms (DELTA) was an investigator-initiated multicenter prospective, parallel, randomized, controlled clinical trial. Patients had 4- to 12-mm unruptured aneurysms. Treatment allocation to either 15- (experimental) or 10-caliber coils (control group) was randomized 1:1 using a Web-based platform. The primary efficacy outcome was a major recurrence or a residual aneurysm at follow-up angiography at 12 ± 2 months adjudicated by an independent core lab blinded to the treatment allocation. Secondary outcomes included indices of treatment success and standard safety outcomes. Recruitment of 564 patients was judged necessary to show a decrease in poor outcomes from 33% to 20% with 15-caliber coils.

RESULTS

Funding was interrupted and the trial was stopped after 210 patients were recruited between November 2013 and June 2017. On an intent-to-treat analysis, the primary outcome was reached in 37 patients allocated to 15-caliber coils and 36 patients allocated to 10-caliber coils (OR = 0.931; 95% CI, 0.528-1.644; P = .885). Safety and other clinical outcomes were similar. The 15-caliber coil group had a higher mean packing density (37.0% versus 26.9%, P = .0001). Packing density had no effect on the primary outcome when adjusted for initial angiographic results (OR = 1.001; 95% CI, 0.981-1.022; P = .879).

CONCLUSIONS

Coiling of aneurysms randomized to 15-caliber coils achieved higher packing densities compared with 10-caliber coils, but this had no impact on the angiographic outcomes at 1 year, which were primarily driven by aneurysm size and initial angiographic results.

Estimated pretreatment hemodynamic prognostic factors of aneurysm recurrence after endovascular embolization

BACKGROUND:

Hemodynamic factors play important roles in aneurysm recurrence after endovascular treatment.

OBJECTIVE:

Predicting the risk of recurrence by hemodynamic analysis using an untreated aneurysm model is important because such prediction is required before treatment.

METHODS:

We retrospectively analyzed hemodynamic factors associated with aneurysm recurrence from pretreatment models of five recurrent and five stable posterior communicating artery (Pcom) aneurysms with no significant differences in aneurysm volume, coil packing density, or sizes of the dome, neck, or Pcom. Hemodynamic factors of velocity ratio, flow rate, pressure ratio, and wall shear stress were investigated.

RESULTS:

Among the hemodynamic factors investigated, velocity ratio and flow rate of the Pcom showed significant differences between the recurrence group and stable group (0.630 ± 0.062 and 0.926 ± 0.051, P= 0.016; 56.4 ± 8.9 and 121.6 ± 6.7, P= 0.008, respectively).

CONCLUSIONS:

Our results suggest that hemodynamic factors may be associated with aneurysm recurrence among Pcom aneurysms. Velocity and flow rate in the Pcom may be a pretreatment prognostic factor for aneurysm recurrence after endovascular treatment.

Relationship between the Volume Rate of Ed Coil (Ed Ratio) and Packing Density in Endosaccular Embolization of Cerebral Aneurysms

PURPOSE

A high packing density (PD) (i.e., coil volume per aneurysm volume) helps prevent recanalization after endosaccular embolization of cerebral aneurysms. We hypothesized that the use of soft coils may be useful to raise PD and retrospectively investigated the correlation between the ED coil volume rate (i.e., volume ratio of all placed coils) and PD in patients treated with endosaccular embolization using this coil.

METHODS

Excluding aneurysms treated with a stent, 292 aneurysms treated using ED coils were included in this study. The 292 aneurysms and aneurysms with ≥30%, ≥40%, and ≥50% ED coil volume rates (202, 168, and 129 aneurysms, respectively) underwent linear regression analysis of the following seven factors' influence on PD:ED ratio, aneurysm volume, neck width, height, maximum diameter, dome-to-neck ratio, and aspect ratio.

RESULTS

Independent factors of a high PD were high ED ratio and small neck width on analyses of aneurysms with an ED ratio of ≥40% and ≥50%. Only neck width was an independent factor on analyses of all 292 aneurysms and aneurysms with ED ratio of ≥30%.

CONCLUSION

The use of ED coils in high volume rate correlated with a high PD and may contribute to prevent recanalization in small aneurysms.

In vitro measurement of the permeability of endovascular coils deployed in cerebral aneurysms

BACKGROUND AND PURPOSE

Aneurysm recurrence is the primary limitation of endovascular coiling treatment for cerebral aneurysms. Coiling is currently quantified by a volumetric porosity measure called packing density (pd). Blood flow through a coil mass depends on the permeability of the coil mass, and not just its pd. The permeability of coil masses has not yet been quantified. Here we measure coil permeability with a traditional falling-head permeameter modified to incorporate idealized aneurysms.

METHODS

Silicone replicas of idealized aneurysms were manufactured with three different aneurysm diameters (4, 5, and 8 mm). Four different coil types (Codman Trufill Orbit, Covidien Axium, Microvention Microplex 10, and Penumbra 400) were deployed into the aneurysms with a target pd of 35%. Coiled replicas were installed on a falling-head permeameter setup and the time taken for a column of fluid above the aneurysm to drop a certain height was recorded. Permeability of the samples was calculated based on a simple modification of the traditional permeameter equation to incorporate a spherical aneurysm.

RESULTS

The targeted 35% pd was achieved for all samples (35%±1%, P=0.91). Coil permeabilities were significantly different from each other (P<0.001) at constant pd. Microplex 10 coils had the lowest permeability of all coil types. Data suggest a trend of increasing permeability with thicker coil wire diameter (not statistically significant).

CONCLUSIONS

A simple in vitro setup was developed to measure the permeabilities of coil masses based on traditional permeametry. Coil permeability should be considered when evaluating the hemodynamic efficacy of coiling instead of just packing density. Coils made of thicker wires may be more permeable, and thus less effective, than coils made from thinner wires. Whether aneurysm recurrence is affected by coil wire diameter or permeability needs to be confirmed with clinical trials.

The effectiveness of Penumbra 400 micro-coils in the embolization of large cerebral aneurysms

BACKGROUND

The objective of this work is to analyze the effectiveness of Penumbra 400 micro-coils in the embolization of large cerebral aneurysms.

MATERIAL AND METHODS

A retrospective analysis has been conducted in a group of 32 patients at the average age of 54.5 years (30-84) for whose embolization the P400 micro-coils (P400) have been used. A control group consisted of 44 patients at the average age of 52.7 years (24-82) in whose aneurysm embolization the 18 micro-coils (MC) have been utilized.

RESULTS

The respective percentages of micro-coil packing density in aneurysm sacs were 31.5% for P400 and 29% for MC. The average P400 fluoroscopy time was 21min, and 34min in case of MC. The average number of used micro-coils was 3.9 for P400 and 5.6 for MC. The radiation dose received by a patient was 1.7Gy/2.2Gy, respectively. The recanalization of P400 has occurred in 14/31 cases (45%), and for MC it has occurred in 23/44 (52%) patients. One patient died due to early recanalization after P400 aneurysm embolization.

CONCLUSION

Procedures with use of the P400 demonstrate minimally higher effectiveness of large aneurysms embolization in comparison with the MS with a not much shorter duration and reduction of a radiation dose that a patient receives.

Embolization with larger-caliber coils can increase packing density: Evidence from the pilot phase of a randomized trial

Background and purpose Endovascular coil embolization of cerebral aneurysms is associated with suboptimal angiographic results in up to 20-30% of patients. Coil packing density has been used as an index of the success of the initial procedure. The trial sought to study the effects of using 15-caliber coils, as compared with 10-caliber coils, on packing density. Methods Does Embolization with Larger coils lead to better Treatment of Aneurysms (DELTA) is an investigator-initiated multicenter prospective, randomized, controlled clinical trial. Patients are randomized 1:1 to embolization with either 10-caliber coils exclusively (control group) or the highest safely achievable proportion of 15-caliber coils and 10-caliber coils if necessary (intervention group) in 4-12-mm aneurysms. The endpoint of the pilot phase of the trial was the capacity to increase packing density of the initial procedure, calculated using a mathematical transformation of the dimensions entered into the case report forms. Secondary outcomes included the total number of coils used per aneurysm, total fluoroscopy time, initial angiographic outcomes and any adverse or undesirable event. Results Seventy patients were recruited between June 2014 and November 2015. Compared with 10-caliber coils, the 15-caliber coil group had a higher median packing density (44% vs 24%, p = 0.017). Results of other outcome measures were similar for the two groups. Conclusion Coiling of small and medium aneurysms randomized to 15-caliber coils achieved higher packing densities compared with coiling using 10-caliber coils.

Endovascular treatment of aneurysms and platinum coil caliber: Study protocol of a randomized, controlled trial

BACKGROUND

Endovascular coil embolization of cerebral aneurysms is an effective treatment for the prevention of aneurysm rebleeding after subarachnoid hemorrhage. It is also often used in unruptured aneurysms, but it is associated with aneurysm remnants and recurrences in up to 20%-33% of patients. We hypothesized that better aneurysm occlusion rates can be achieved with coils of larger caliber.

METHODS

The Does Embolization with Larger coils lead to better Treatment of Aneurysms (DELTA) trial is an investigator-initiated, multicenter, prospective, randomized, controlled clinical trial. To test the hypothesis that 15-caliber coiling systems are superior to 10-caliber coils, 564 patients with aneurysms measuring 4-12 mm will be randomized 1:1 to embolization with either 10-caliber coils exclusively (control group) or the highest safely achievable proportion of 15-caliber coils (intervention group). The primary efficacy endpoint of the trial is the occurrence of a major recurrence or a residual aneurysm at one year. A pilot phase of 165 patients will be conducted to verify feasibility of the coiling strategy, compliance to treatment allocation, safety of a 15-caliber platinum coil embolization strategy, recruitment rates, and the capacity to improve packing density.

DISCUSSION

The DELTA trial will test the hypothesis that the use of coils of larger caliber can improve angiographic results of endovascular coiling.

Large Residual Volume, Not Low Packing Density, Is the Most Influential Risk Factor for Recanalization after Coil Embolization of Cerebral Aneurysms

Background

Tight coil packing with density of at least 20%–25% is known to be important for preventing recanalization after embolization of cerebral aneurysms. However, large aneurysms sometimes recanalize regardless of the packing density, suggesting that the absolute residual volume which is determined by aneurysm volume and packing density may be more important risk factor for recanalization. To validate this hypothesis, we analyzed the factors affecting the outcomes of treated aneurysms at our institute.

Methods and Findings

We included 355 small and large aneurysms. The following six factors were obtained from every case: aneurysm volume (mL), neck size (mm), packing density (%), residual volume (mL), rupture status at presentation, and stent assistance (with or without stent). The data were then subjected to multivariate logistic regression analysis to identify significant risk factors for recanalization. Recanalization occurred in 61 aneurysms (17.2%). Significant predictors for recanalization were aneurysm volume (odds ratio, 15.3; P < 0.001) and residual volume (odds ratio, 30.9; P < 0.001), but not packing density (odds ratio, 0.98; P = 0.341). These results showed that for each 0.1-mL increase in aneurysm volume and residual volume, the risk of recanalization increased by 1.3 times and 1.4 times, respectively.

Conclusions

The most influential risk factor for recanalization after coil embolization was residual volume, not packing density. The larger the aneurysm volume, the greater the packing density has to be to minimize the residual volume and risk of recanalization. Since tight coil packing has already been aimed, further innovation of coil property or embolization technique may be needed. Otherwise, different treatment modality such as flow diverter or parent artery occlusion may have to be considered.

Effects of anatomic characteristics of aneurysms on packing density in endovascular coil embolization: analysis of a single center's experience

When embolizing cerebral aneurysms, dense coil packing may prevent recanalization but this may be influenced by the aneurysm morphology. We have analyzed retrospectively the relationship between anatomic features and the volumetric coil packing density. We analyzed 452 aneurysms in 434 patients treated by coil embolization without stenting, expressing packing density as volume embolization ratio (VER, volume of inserted coils/aneurysm volume). Six morphological variables (neck width, height, maximum diameter, dome to neck ratio (DNR), and aspect ratio), aneurysm location, and whether the aneurysm was ruptured or unruptured were analyzed with respect to dense (VER ≥20%) or loose (VER <20%) packing densities, using logistic regression analysis and ROC analysis. Among 452 aneurysms, VERs >20% were achieved for 272 aneurysms, with a mean VER of 24.7%. The mean VER of the remaining 180 aneurysms was 15.6%. In univariate analyses, the predictors for dense packing were having an anterior circulation, DNR, aspect ratio, and neck width. In multivariate analysis, the independent predictors were smaller neck width (odds ratio (OR) 0.8735; 95% confidence interval (CI) 0.7635-0.9993) and larger aspect ratio (OR 1.6679; 95% CI 1.0460-2.6594). ROC analysis showed optimal cutoff values for an aspect ratio of 1.35 (sensitivity 69.5%, specificity 51.7%) and a neck width of 3.13 mm (sensitivity 51.1%, specificity 27.8%). Although dense coil packing is still difficult to achieve in wide-necked aneurysms without the use of stents, packing with VER >20% is expected to be achieved when the height is 1.35 times larger than the neck width.

Survival Analysis of Risk Factors for Major Recurrence of Intracranial Aneurysms after Coiling

Background: Recurrence after intracranial aneurysm coiling is a highly prevalent outcome, yet to be understood. We investigated clinical, radiological and procedural factors associated with major recurrence of coiled intracranial aneurysms. Methods: We retrospectively analyzed prospectively collected coiling data (2003-12). We recorded characteristics of aneurysms, patients and interventional techniques, pre-discharge and angiographic follow-up occlusion. The Raymond-Roy classification was used; major recurrence was a change from class I or II to class III, increase in class III remnant, and any recurrence requiring any type of retreatment. Identification of risk factors associated with major recurrence used univariate Cox Proportional Hazards Model followed by multivariate regression analysis of covariates with P<0.1. Results: A total of 467 aneurysms were treated in 435 patients: 283(65%) harboring acutely ruptured aneurysms, 44(10.1%) patients died before discharge and 33(7.6%) were lost to follow-up. A total of 1367 angiographic follow-up studies (range: 1-108 months, Median [interquartile ranges (IQR)]: 37[14-62]) was performed in 384(82.2%) aneurysms. The major recurrence rate was 98(21%) after 6(3.5-22.5) months. Multivariate analysis (358 patients with 384 aneurysms) revealed the risk factors for major recurrence: age>65 y (hazard ratio (HR): 1.61; P=0.04), male sex (HR: 2.13; P<0.01), hypercholesterolemia (HR: 1.65; P=0.03), neck size ≥4 mm (HR: 1.79; P=0.01), dome size ≥7 mm (HR: 2.44; P<0.01), non-stent-assisted coiling (HR: 2.87; P=0.01), and baseline class III (HR: 2.18; P<0.01). Conclusion: Approximately one fifth of the intracranial aneurysms resulted in major recurrence. Modifiable factors for major recurrence were choice of stent-assisted technique and confirmation of adequate baseline occlusion (Class I/II) in the first coiling procedure.

Bare platinum coils vs. HydroCoil in the treatment of unruptured intracranial aneurysms-A single center randomized controlled study

PURPOSE

The HydroCoil Embolic System (HES) was developed to improve aneurysm filling to provide superior occlusion efficacy, reduce retreatment rates and enhance long-term durability. We performed a randomized clinical trial to compare the effectiveness of bare platinum coils (BPC) vs. HES for unruptured intracranial aneurysms.

METHODS

Ninety-six patients underwent endovascular coiling of unruptured intracranial aneurysms. The aneurysms were randomized equally to receive BPC or HES. Immediate angiographic results, number of coils used and complications were evaluated and all cases had 12-month follow-up angiography.

RESULTS

Immediate angiographic results demonstrated that 84.0% of aneurysms treated with HES were completely occluded compared to 76.1% of aneurysms treated with BPC (p=0.3310). The mean number of coils utilized to fill the aneurysm was significantly lower in the HES arm (5.04 vs. 6.93). Additional adjunctive techniques were performed in 51.1% of all cases. There were seven patients (7.3%) with postoperative complications during the study period. The coil type used during the treatment did not demonstrate any significant differences on the overall recurrence rate (HES - 18.0%, BPC - 17.4%, p=0.9712). There was a statistically significant difference in the aneurysm size and the neck width between completely occluded aneurysms and aneurysms with residual flow in both immediate angiographic and mid-term follow-up.

CONCLUSIONS

Overall, aneurysm size and neck width are the main risk factors associated with aneurysm recurrence. HES compared to BPC required less total number of coils to provide a denser aneurysm filling. However, there were equivocal results with both devices, at the mid-term angiographic follow-up.

Validation and initial application of a semiautomatic aneurysm measurement software: a tool for assessing volumetric packing attenuation

BACKGROUND AND PURPOSE

Precise aneurysm measurements and volume embolization ratios are essential for long-term durability of endovascular coil embolization. We evaluated the accuracy of newly developed semiautomatic cerebral aneurysm measurement software, NeuroVision, and explored the value of volume embolization ratio in the prediction of re-treatment.

MATERIALS AND METHODS

We compared software-derived volume measurements of 4 silicone aneurysm models with those calculated with an approximation formula and ground truth values (validation study). We used NeuroVision to retrospectively evaluate outcomes of 100 unruptured aneurysms (97 patients) treated with embolization (clinical study). Aneurysm size (height, width, and neck), volume, and volume embolization ratios were calculated for 3 groups (stable, recanalization, and re-treatment) and were compared.

RESULTS

This validation study illustrated higher accuracy of NeuroVision in computing aneurysm volume compared with an approximation formula: percentage absolute errors were 4.50% ± 3.18% and 23.07% ± 17.60%, with maximal percentage absolute errors of 8.99% and 45.63%, respectively. Of 100 unruptured aneurysms, 20 recanalized and 12 were re-treated. Average volume embolization ratios of stable and re-treated aneurysms were 24.88% ± 5.91% and 20.50% ± 4.06%, respectively (P ≤ .01). The optimal volume embolization ratio cutoff point for re-treatment was < 19.15%, at which the Youden index was 0.50 (sensitivity, 58.33%; specificity, 87.50%; area under the receiver operating characteristic curve, 0.74).

CONCLUSIONS

The NeuroVision software provided accurate aneurysm volume measurements and may be a useful standardized tool to measure aneurysm size and volume, especially for multicenter clinical studies. Volume embolization ratio may be a valuable predictor of aneurysm occlusion changes.

Review of 2 decades of aneurysm-recurrence literature, part 1: reducing recurrence after endovascular coiling

SUMMARY

Angiographic recurrence following endovascular therapy is an indirect measure of the potential for hemorrhage. Because patients and physicians consider recurrence to be a suboptimal outcome with some chance of future hemorrhage, much effort has been expended to reduce the incidence of recurrence. The literature regarding aneurysm recurrence following endovascular therapy, spanning 2 decades, is extensive. We will review and summarize the effort to reduce recurrence following endovascular treatment of cerebral aneurysms.

IN VITRO QUANTIFICATION OF THE SIZE DISTRIBUTION OF INTRASACCULAR VOIDS LEFT AFTER ENDOVASCULAR COILING OF CEREBRAL ANEURYSMS

PURPOSE

Endovascular coiling of cerebral aneurysms remains limited by coil compaction and associated recanalization. Recent coil designs which effect higher packing densities may be far from optimal because hemodynamic forces causing compaction are not well understood since detailed data regarding the location and distribution of coil masses are unavailable. We present an in vitro methodology to characterize coil masses deployed within aneurysms by quantifying intra-aneurysmal void spaces.

METHODS

Eight identical aneurysms were packed with coils by both balloon- and stent-assist techniques. The samples were embedded, sequentially sectioned and imaged. Empty spaces between the coils were numerically filled with circles (2D) in the planar images and with spheres (3D) in the three-dimensional composite images. The 2D and 3D void size histograms were analyzed for local variations and by fitting theoretical probability distribution functions.

RESULTS

Balloon-assist packing densities (31±2%) were lower (p=0.04) than the stent-assist group (40±7%). The maximum and average 2D and 3D void sizes were higher (p=0.03 to 0.05) in the balloon-assist group as compared to the stent-assist group. None of the void size histograms were normally distributed; theoretical probability distribution fits suggest that the histograms are most probably exponentially distributed with decay constants of 6-10 mm. Significant (p<=0.001 to p=0.03) spatial trends were noted with the void sizes but correlation coefficients were generally low (absolute r<=0.35).

CONCLUSION

The methodology we present can provide valuable input data for numerical calculations of hemodynamic forces impinging on intra-aneurysmal coil masses and be used to compare and optimize coil configurations as well as coiling techniques.

Complex-shaped platinum coils for brain aneurysms: higher packing density, improved biomechanical stability, and midterm angiographic outcome

BACKGROUND AND PURPOSE

Five to 60% of coiled brain aneurysms recanalize, generally because of coil compaction. In vitro exclusive use of complex-shaped coils allows better packing of the aneurysmal sac and the neck as compared with helical coils. We report a single-center, prospective study using complex coils. Safety, packing density, and recanalization rate were evaluated.

MATERIALS AND METHODS

Seventy-seven aneurysms were embolized using complex coils alone. Aneurysms had a volume of 265 mm3 (diameter: 7.1+/-3.3 mm) and a neck size of 4.1+/-1.8 mm (range: 1.5-12 mm). Average follow-up available in 31 patients was 10.5+/-7.6 months (range: 3-36 months). Primary angiographic endpoints included aneurysmal recanalization and (re)rupture. Primary adverse events included stroke or death.

RESULTS

Complete or near-complete occlusion was achieved in all of the aneurysms but required balloon assistance in 24.6%. The packing density was computed as 37%+/-13%. No rerupture was observed during the follow-up interval. Recanalization was seen in 4 (12.9%) of 31. Two basilar tip aneurysms underwent a safe and complete recoiling. Periprocedural nondevice-related neurologic deficits were seen in 2 (2.9%) of 69 patients.

CONCLUSIONS

The use of complex-shaped coils allows higher packing density, which may improve the recanalization rate. Basilar tip aneurysms remain a challenge.

Acute Ruptured Intracranial Aneurysm Packing with HydroCoil Embolic System: Initial Clinical Experience

The HydroCoil Embolic System (HES; MicroVention, Aliso Viejo, CA, USA) was developed to improve the efficacy of endovascular treatment of cerebral aneurysms. The HES may reduce recurrences of aneurysms by allowing for increased packing density compared with platinum coils. We report our initial experience with the HES in the treatment of 31 patients with acute ruptured cerebral aneurysms. The HES is another safe and effective material for aneurysms embolization, which provided substantially improved volumetric packing of the aneurysm lumen.

Ready or not, here they come: randomized trials evaluating new endovascular aneurysm therapies

Randomized trials evaluating endovascular therapy are currently underway. The results of these trials will present us with both new answers and new questions.

Embolization of Intracranial Aneurysms With Hydrogel-Coated Coils Versus Inert Platinum Coils

Background and Purpose— The durability of aneurysm coil embolization is thought to depend on packing density. The expansile property of hydrogel coating on coils increases volumetric packing per coil length. We describe our experience using hydrogel-coated coils (HydroCoils) compared with inert platinum coils in intracranial aneurysm embolization.

Methods— Fifty aneurysms embolized primarily using HydroCoils from 2003 to 2004 were compared with 57 volume- and shape-matched aneurysms treated with standard platinum coils from 2000 to 2003. Outcome measures included volumetric percentage occlusion (VPO), length and number of coils used, procedure time, fluoroscopy time, contrast volume, coil cost, length of hospital stay, and durability of therapy.

Results— Seventeen/26/5 small/medium/large aneurysms treated with HydroCoils were matched with 29/24/4 small/medium/large aneurysms treated with inert platinum. HydroCoil embolization yielded significantly greater VPO (84.8% versus 29.8%; P <0.001), decreased average total coil length used per aneurysm (33.2 versus 44.3 cm), reduced fluoroscopy time (53.2 versus 65.2 minutes; P =0.016), but increased contrast volume used (174.8 versus 112.9 cc; P <0.001). There were no differences in length of hospital stay. Procedure-related morbidity and mortality rates in the HydroCoil cohort were 4% and 0%, respectively. Follow-up angiography at mean 12.3 months revealed lower aneurysm recurrence rates (17% versus 24%; number-needed-to-treat [NNT] 14.3). Initial costs associated with HydroCoil embolization were higher ($5835 versus $4017; P =0.004) but countered by lower retreatment rates (10% versus 17%; NNT 14.3).

Conclusions— HydroCoil embolization achieves greater aneurysm packing density with decreased coil length. Initial durability data favor HydroCoils, with lower recurrence and retreatment rates.

HydroCoil for Endovascular Aneurysm Occlusion (HEAL) study: periprocedural results

BACKGROUND AND PURPOSE

The HydroCoil Embolic System (HES) was developed to improve the efficacy of endovascular treatment of cerebral aneurysms. The purpose of this study is to study the periprocedural results in patients with cerebral aneurysms treated with HES.

METHODS

We report the initial periprocedural results in 191 cerebral aneurysms treated with HES in the HydroCoil for Endovascular Aneurysm Occlusion, or HEAL, study. Initial aneurysm occlusion and periprocedural complication rates were evaluated and compared with historical control data regarding aneurysms treated with platinum coils.

RESULTS

An initial occlusion result of "complete" or "near-complete" was achieved in 91.8% of aneurysms. Periprocedural thromboembolic events occurred in 8.1% of aneurysms treated with neurologic deficits related to thromboemboli occurring in 2.1% of aneurysms treated. Intraprocedural aneurysm perforations occurred in 2.8% of previously ruptured aneurysms, and in 0% of previously unruptured aneurysms.

CONCLUSION

The initial occlusion success and complication rate when HES is used to treat cerebral aneurysms is not significantly different from platinum coils. Follow-up angiography is currently being collected and will be evaluated to determine if use of the HES reduces the rate of aneurysm recurrence.

Computer simulation of flow dynamics in paraclinoidal aneurysms

SUMMARY

Endovascular treatment, which is very useful method especially for paraclinoidal aneurysms, has the limitations of coil compaction and recanalization, which are difficult to predict. We tried to understand flow dynamic features, one of the important factors of such problems, using computer flow dynamics (CFD) simulations. CFD simulations were made in paraclinoidal aneurysm model of different size and protruded directions. Flow patterns, flow velocities and pressure are analyzed. Although the pressure on the aneurismal orifice is highest in the aneurysm protruding vertically - upward, the flow velocity is highest in the superior-medial protruding one. Significant difference is not observed in either flow patterns, flow velocities or pressures on the aneurismal orifices between the sizes of aneurismal sac. Among paraclinoidal aneurysms, an aneurysm protruding to superior-medially receives the most severe haemodynamic stresses at the orifice and the aneurysm size does not cause significant differences in the aspect of flow dynamics. It should be considered in the treatment of such aneurysms.

Short-term outcome of intracranial aneurysms treated with polyglycolic acid/lactide copolymer-coated coils compared to historical controls treated with bare platinum coils: a single-center experience

BACKGROUND AND PURPOSE

Aneurysm recanalization is an innate problem in endovascular treatment of aneurysms with coils. A coated coil system, covered with a bioabsorbable polymeric material (polyglycolic acid/lactide copolymer, PGLA), was developed to accelerate intra-aneurysmal clot organization and fibrosis. The purpose of this study was to evaluate the efficacy and safety of the PGLA-coated coils in patients with intracranial aneurysms and to compare the outcome with that of bare platinum coils.

PATIENTS AND TECHNIQUES

Fifty-one patients harboring 56 intracranial aneurysms underwent endovascular embolization with the PGLA-coated coils. In the control group were 78 consecutive patients, harboring 87 aneurysms, who underwent coil embolization with bare platinum coils. The authors compared coil volume, packing attenuation, degree of occlusion of aneurysms, procedure-related complications, and follow-up results between the 2 groups.

RESULTS

The PGLA-coil group showed comparable data regarding rate of total or near-total occlusion of the aneurysm, incidence procedure-related thromboembolism, and management outcome. Mean coil volume deployed and packing attenuation of the PGLA-coil group were significantly higher than those of the bare-coil group (P = .0026 and P < .0001, respectively). Radiologic follow-up evaluation revealed recanalization in 14 of 39 aneurysms (major recanalization in 5 [13%] and minor recanalization in 9 [23%]) among the PGLA-coil group and in 29 of 64 aneurysms (major recanalization in 9 [14%] and minor recanalization in 20 [31%]) among the bare-coil group.

CONCLUSION

In this study, the incidence of recanalization was not different in aneurysms treated with PGLA-coated coils compared with historical controls treated with bare platinum coils.

Absent relationship between the coil-embolization ratio in small aneurysms treated with a single detachable coil and outcomes

BACKGROUND AND PURPOSE

Although attenuated coil packing of intracranial aneurysms is an important goal of endovascular embolization, because of their small size, some aneurysms can only be treated with a single embolization coil. We retrospectively analyzed small aneurysms treated with a single Guglielmi detachable coil (GDC) to determine whether the coil-embolization ratio (CER) is predictive of embolization stability.

METHODS

The CER was determined for 25 small (<7-mm diameter) intracranial aneurysms, each treated with a single embolization coil. The largest aneurysm dimension, estimated by comparison to anatomic landmarks, was used for volume calculation based on a spherical model. Coil volumes were according to manufacturer specifications. CER was calculated by the formula (coil volume/aneurysm volume) x 100%. Embolization stability was assessed by angiographic follow-up.

RESULTS

The average CER for all aneurysms was 8.2% (SD, 6.5%; range, 0.6%-21.1%). Twelve percent of the aneurysms had a CER >20%. Follow-up angiographic assessment was conducted at an average of 30.8 months after initial treatment. Eighty-four percent of the aneurysms were obliterated. One large (6 x 10 mm) and 3 small (<1 mm) recurrences were identified. The average CER for unchanged aneurysms was 8.0% (SD, 5.9%) and for the recurrent aneurysms was 8.8% (SD, 8.7%), which was not statistically significant.

CONCLUSION

Small aneurysms treated with a single coil achieved satisfactory stability despite having a low average packing attenuation. CER was not predictive of recurrence in small intracranial aneurysms treated with a single detachable coil.

Endovascular coil embolization of intracranial aneurysms: important factors related to rates and outcomes of incomplete occlusion

Object. The authors report on important factors that influenced clinical and angiographically demonstrated outcomes in patients treated using coil embolization.

Methods. This study included 160 consecutive patients who underwent endovascular coil embolization for treatment of intracranial aneurysms. Univariate and multivariate logistic regression analyses were performed to assess factors that influenced the immediate posttreatment angiographic result. Cox regression analysis was used to establish factors related to the occurrence of negative events as well as a curve indicating the time to a negative event. Negative events were defined as aneurysm remnant increase, repeated treatment, rebleeding, or death during periprocedural hospitalization.

Seventy-three percent of the patients treated in this study were independent or demonstrated no deficit (Glasgow Outcome Scale [GOS] Score 4 or 5) at a mean follow up of 18.2 months. The annual delayed rebleeding rate was 0.45%. Fifty percent of patients (65 of 131) suffered a negative event within 13 ± 14 months (standard deviation). Statistically significant factors associated with the occurrence of negative events were rupture status (p = 0.0128) and immediate posttreatment angiographic result (p < 0.001). Overall clinical outcome assessed using the GOS was significantly related to the immediate posttreatment angiographic result (χ2 = 4.788, p = 0.029). The immediate posttreatment angiographic results were significantly influenced by catheter stability (p = 0.0012), aneurysm geometry (that is, simple or complex, p = 0.0053), and aneurysm neck diameter (p = 0.0205).

Conclusions. A good or excellent clinical outcome can be obtained in most patients treated using endovascular coil embolization of intracranial aneurysms. Note, however, that a significant number of patients treated using traditional platinum coils will harbor unstable aneurysm remnants or require repeated treatment.

Relation between aneurysm volume, packing, and compaction in 145 cerebral aneurysms treated with coils

PURPOSE

To assess the relation between aneurysm volume, packing, and compaction in cerebral aneurysms treated with coils.

MATERIALS AND METHODS

The volumes of 145 aneurysms that were treated with coils were calculated with biplanar angiographic images and a custom-designed method. Partially thrombosed aneurysms were excluded. Packing was defined as the ratio between the volume of the inserted coils and the volume of the aneurysm and was calculated for all 145 aneurysms. Results at 6-month follow-up angiography were dichotomized into presence or absence of compaction.

RESULTS

Aneurysm volume, packing, and compaction at 6-month follow-up were closely related. Large aneurysm volume was associated with low packing and frequent compaction. High packing prevents compaction. If the aneurysm volume was packed for 24% or more with coils, compaction did not occur in aneurysms with a volume of less than 600 mm(3). In small aneurysms with volumes of less than 200 mm(3), compaction did not occur when packing was above 20%.

CONCLUSION

The common practice of inserting as many coils as possible in cerebral aneurysms is sensible in trying to avoid compaction. In aneurysms with packing of 24% or more, no compaction occurred at 6-month angiographic follow-up. In aneurysms with a volume of more than 600 mm(3), high packing could not be achieved, which resulted in compaction in the majority of aneurysms.

Aneurysm packing with HydroCoil Embolic System versus platinum coils: initial clinical experience

The HydroCoil Embolic System (HES; MicroVention, Aliso Viejo, CA) was developed to improve the efficacy of endovascular treatment of cerebral aneurysms. The HES may reduce recurrences of aneurysms by allowing for increased packing density as compared with platinum coils. We report our initial experience with the HES in the treatment of 11 patients with cerebral aneurysms and compare findings to those in size-matched control cases treated with platinum coils. The HES provided substantially improved volumetric packing of the aneurysm lumen relative to standard platinum coils (73% vs. 32%; P=.0001).