Evaluation of the Stability of Small Ruptured Aneurysms with a Small Neck after Embolization with Guglielmi Detachable Coils: Correlation between Coil Packing Ratio and Coil Compaction

EFFECTS OF THE ANEURYSM TREATMENT METHOD ON COIL PACKING DENSITY AND ITS RELATIONSHIP WITH THE OSTIUM AREA

PURPOSE

To test the following hypotheses: (1) balloon or stent assistance increases coil packing density (CPD) in the endovascular treatment of intracranial aneurysms and (2) CPD is related to the ostium area and volume of the aneurysm.

MATERIALS AND METHODS

This retrospective study included 60 ruptured and unruptured (54 and 6, respectively) aneurysms treated between August 2017 and December 2019 in the authors' institution with simple coiling (n=18), balloon-assisted coiling (n=7), or stent-assisted coiling (n=35). Aneurysm volume and ostium area measurements were obtained using commercial software from three-dimensional digital subtraction angiography images. Coil sizes were retrieved from patient files, and coil volume measurements were obtained using https://www.angiocalc.com/. Analysis of covariance, multivariable covariance analysis, and Pearson's correlation analyses were performed.

RESULTS

The median values for the aneurysm volume, coil volume, CPD, and ostium area were 63.4 (range 5.5-1771.4) mm³, 23.13 (2.03-296.95) mm³, 33.29% (13.41%-81.02%), and 10.7 (2.7-49.9) mm², respectively. Multivariate analysis showed that the CPD values were not significantly different among the treatment groups, although the ostium area differed significantly between the simple and stent-assisted coiling groups (P<.05). Pearson's correlations showed that similar to aneurysm volume, the ostium area was negatively correlated with CPD (r=-0.321, P<.05).

CONCLUSION

In cerebral aneurysms treated with balloon- or stent-assisted coiling, the CPD value does not differ from that in aneurysms treated with simple coiling.

Experimental Study of Coil Compaction: Impact of Pulsatile Stress

Objective

Coil compaction after aneurysm embolization is one of the major issues associated with aneurysm recurrence. On the presumption that pulsatile stress to the aneurysm is responsible for coil compaction, we developed an experimental model in vitro to visualize the mechanical stresses exerted by blood pressure and pulse and their relation to coil compaction.

Methods

A closed-type non-circulation system was developed by installing a syringe that generated pressure at one end of a tube, along with a spherical aneurysm made of silicone and a pressure sensor in the bifurcated end. We installed a fixed-pressure model under a steady pressure of 300 mmHg while the pressure-fluctuation model simulated the pressure variations using a plunger (in a syringe) by using a motor that applied pulsatile stress in the range of 50 mmHg for a 10-ms cycle. We devised four types of aneurysms with different depths and the same coil length. After coil packing, the aneurysms were observed for 3 days (the observation period in the pressure-fluctuation model corresponded to approximately 300 days in real time). The distance from the datum point to the observable coil loops was determined as the initial position, and the temporal change in the distance from that position was measured.

Results

In the fixed-pressure model, the average distance of coil movement was very small (less than ±0.1 mm). In the pressure-fluctuation model, the movement of coils was observed to be significant for the two longest depths (0.11 and 0.14 mm). The maximal dynamic change in coil movement was observed on the second day. The range of movement was observed to decrease thereafter.

Conclusion

Our experimental study enabled the observation of coil movement within a short duration. It examined coil compaction by applying pulsed pressure to the coils at high speeds. Consequently, a shift of the coil loops inside the incompletely occluded aneurysms was detected on applying a pulsed pressure.

The evolution of intracranial aneurysm treatment techniques and future directions

Treatment techniques and management guidelines for intracranial aneurysms (IAs) have been continually developing and this rapid development has altered treatment decision-making for clinicians. IAs are treated in one of two ways: surgical treatments such as microsurgical clipping with or without bypass techniques, and endovascular methods such as coiling, balloon- or stent-assisted coiling, or intravascular flow diversion and intrasaccular flow disruption. In certain cases, a single approach may be inadequate in completely resolving the IA and successful treatment requires a combination of microsurgical and endovascular techniques, such as in complex aneurysms. The treatment option should be considered based on factors such as age; past medical history; comorbidities; patient preference; aneurysm characteristics such as location, morphology, and size; and finally the operator’s experience. The purpose of this review is to provide practicing neurosurgeons with a summary of the techniques available, and to aid decision-making by highlighting ideal or less ideal cases for a given technique. Next, we illustrate the evolution of techniques to overcome the shortfalls of preceding techniques. At the outset, we emphasize that this decision-making process is dynamic and will be directed by current best scientific evidence, and future technological advances.

Recanalization of Embolized Endovascular Intracranial Aneurysms and Changes in the Blood Viscosity: A Pilot Study

Background

The purpose of our research was to evaluate the relationships between blood viscosity and recanalization of coiled intracranial aneurysms.

Material/Methods

The study included consecutives patients treated endovascularly by a team of experienced neurosurgeons and neuroradiologists due to brain aneurysm. A total of 50 patients (the average age was 57.48 years, SD=13.71) were assigned to 2 groups: group A with recanalization (4 male and 8 female patients) and group B without recanalization (10 male and 28 female patients) were examined. All patients underwent a 6-month follow-up of the whole-blood viscosity test with a Brookfield DV III+pro cone-plate viscometer using the Rheocalc program. Differences between groups were assessed using the Statistica 12 computer program (StatSoft Inc., Tulsa, OK, USA).

Results

Studies have shown no significant difference in the age range between group A and B (P=0.31). In group A, higher viscosity values were found for whole blood [median: 4.14 dyn×sec/cm² (mPa×sec) quartile range 0.42], compared to group B [median: 3.92 dyn×sec/cm² (mPa×sec); quartile range 0.40; (P=0.04)]. This difference was significant (P=0.04). Additionally, the level of hematocrit was positively related with recanalization, the higher the hematocrit, the more frequent recanalization. A very strong and statistically significant relationship occurred between the frequency of recanalization and smoking (P<0.001).

Conclusions

The occurrence of higher values of whole blood viscosity which increase turbulent flow through the vessels may be a risk for recanalization of the coiled intracranial aneurysm.

Convolutional Neural Networks for the Detection and Measurement of Cerebral Aneurysms on Magnetic Resonance Angiography

Aneurysm size correlates with rupture risk and is important for treatment planning. User annotation of aneurysm size is slow and tedious, particularly for large data sets. Geometric shortcuts to compute size have been shown to be inaccurate, particularly for nonstandard aneurysm geometries. To develop and train a convolutional neural network (CNN) to detect and measure cerebral aneurysms from magnetic resonance angiography (MRA) automatically and without geometric shortcuts. In step 1, a CNN based on the U-net architecture was trained on 250 MRA maximum intensity projection (MIP) images, then applied to a testing set. In step 2, the trained CNN was applied to a separate set of 14 basilar tip aneurysms for size prediction. Step 1-the CNN successfully identified aneurysms in 85/86 (98.8% of) testing set cases, with a receiver operating characteristic (ROC) area-under-the-curve of 0.87. Step 2-automated basilar tip aneurysm linear size differed from radiologist-traced aneurysm size on average by 2.01 mm, or 30%. The CNN aneurysm area differed from radiologist-derived area on average by 8.1 mm2 or 27%. CNN correctly predicted the area trend for the set of aneurysms. This approach is to our knowledge the first using CNNs to derive aneurysm size. In particular, we demonstrate the clinically pertinent application of computing maximal aneurysm one-dimensional size and two-dimensional area. We propose that future work can apply this to facilitate pre-treatment planning and possibly identify previously missed aneurysms in retrospective assessment.

Risk factors for recurrence and retreatment after endovascular treatment of intracranial saccular aneurysm larger than 8 mm

BACKGROUND

Large intracranial aneurysm is challenging for both surgical and endovascular treatment. High recurrence and retreatment rates are still limitations for endovascular treatment. Analysing risk factors of recurrence after endovascular treatment can be useful for planning future treatment strategies.

METHOD

We retrospectively reviewed patients with intracranial saccular aneurysm (≥ 8 mm) who underwent endovascular treatment from 2008 to 2017 at our institution. The demographic features, clinical information and angiographic results were analysed to reveal the risk factors for recurrence and retreatment. Subgroup analysis was performed according to packing density (PD) and stent insertion status.

RESULTS

The total recurrence and retreatment rates were 25.7% (44/171) and 10.5% (18/171), respectively. Independent risk factors for recurrence after endovascular treatment were larger aneurysm size (OR 1.32; 95% CI 1.17-1.51; p < 0.001), ruptured status (OR 3.91; 95%CI 1.44-10.90; p = 0.008), initial incomplete occlusion (OR 2.72; 95%CI 1.18-6.41; p = 0.020), and low dome-to-neck ratio (OR 0.61; 95%CI 0.36-0.97; p = 0.047). The recurrence rate for the no-stent with low PD (< 17.5%) group was 50% (14/28); 37.5% (6/16) for stent-assisted coil (SAC) with low PD group, 22.0% (20/91) for no-stent with high PD group and 11.1% (4/36) for SAC with high PD group.

CONCLUSION

The independent risk factors for recurrence after endovascular treatment in large (≥ 8 mm) intracranial saccular aneurysm were larger aneurysm size, ruptured status, low dome-to-neck ratio and initial incomplete occlusion state. SAC is a useful method for lowering recurrence after endovascular treatment for relatively large (≥ 8 mm) cerebral aneurysm.

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.

Simple Coiling versus Stent-Assisted Coiling of Paraclinoid Aneurysms: Radiological Outcome in a Single Center Study

Objective

Paraclinoid aneurysms are a group of aneurysms arising at the distal internal carotid artery. Due to a high incidence of small, wide-necked aneurysms in this zone, it is often challenging to achieve complete occlusion when solely using detachable coils, thus stent placement is often required. In the present study, we aimed to investigate the effect of stent placement in endovascular treatment of paraclinoid aneurysms.

Methods

Data of 98 paraclinoid aneurysms treated by endovascular approach in our center from August 2005 to June 2016 were retrospectively reviewed. They were divided into two groups: simple coiling and stent-assisted coiling. Differences in the recurrence and progressive occlusion between the two groups were mainly analyzed. The recurrence was defined as more than one grade worsening according to Raymond-Roy Classification or major recanalization that is large enough to permit retreatment in the follow-up study compared to the immediate post-operative results.

Results

Complete occlusion was achieved immediately after endovascular treatment in eight out of 37 patients (21.6%) in the stent-assisted group and 18 out of 61 (29.5%) in the simple coiling group. In the follow-up imaging studies, the recurrence rate was lower in the stent-assisted group (one out of 37, 2.7%) compared to the simple coiling group (13 out of 61, 21.3%) (p=0.011). Multivariate logistic regression model showed lower recurrence rate in the stent-assisted group than the simple coiling group (odds ratio [OR] 0.051, 95% confidence interval [CI] 0.005-0.527). Furthermore there was also a significant difference in the rate of progressive occlusion between the stent-assisted group (16 out of 29 patients, 55.2%) and the simple coiling group (10 out of 43 patients, 23.3%) (p=0.006). The stent-assisted group also exhibited a higher rate of progressive occlusion than the simple coiling group in the multivariate logistic regression model (OR 3.208, 95% CI 1.106-9.302).

Conclusion

Use of stents results in good prognosis not only by reducing the recurrence rate but also by increasing the rate of progressive occlusion in wide-necked paraclinoid aneurysms. Stent-assisted coil embolization can be an important treatment strategy for paraclinoid aneurysms when considering the superiority of long term outcome.

Successful Retreatment of Recurrent Intracranial Vertebral Artery Dissecting Aneurysms After Stent-Assisted Coil Embolization: A Self-Controlled Hemodynamic Analysis

BACKGROUND

Intracranial vertebral artery dissecting aneurysms (VADAs) tend to recur despite successful stent-assisted coil embolization (SACE). Hemodynamics is useful in evaluating aneurysmal formation, growth, and rupture. Our aim was to evaluate the hemodynamic patterns of the recurrence of VADA.

METHODS

Between September 2009 and November 2013, all consecutive patients with recurrent VADAs after SACE in our institutions were enrolled. Recurrence was defined as recanalization and/or regrowth. We assessed the hemodynamic alterations in wall shear stress (WSS) and velocity after the initial SACE and subsequently after retreatment of the aneurysms that recurred.

RESULTS

Five patients were included. After the initial treatment, 3 patients showed recanalization and 2 showed regrowth. In the 2 patients with regrowth, the 2 original aneurysms maintained complete occlusion; however, de novo aneurysm regrowth was confirmed near the previous site. Compared with 3 recanalized aneurysms, the completely occluded aneurysms showed high mean reductions in velocity and WSS after initial treatment (velocity, 77.6% vs. 57.7%; WSS, 74.2% vs. 52.4%); however, WSS remained high at the region near the previous lesion where the new aneurysm originated. After the second retreatment, there was no recurrence in any patient. Compared with the 3 aneurysms that recanalized, the 4 aneurysms that maintained complete occlusion showed higher reductions in velocity (62.9%) and WSS (71.1%).

CONCLUSIONS

Our series indicated that hemodynamics might have an important role in recurrence of VADAs. After endovascular treatment, sufficient hemodynamic reduction in aneurysm dome, orifice, and parent vessel may be one of the key factors for preventing recurrence in VADAs.

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.

The significant impact of framing coils on long-term outcomes in endovascular coiling for intracranial aneurysms: how to select an appropriate framing coil

OBJECTIVE The importance of a framing coil (FC)-the first coil inserted into an aneurysm during endovascular coiling, also called a lead coil or a first coil-is recognized, but its impact on long-term outcomes, including recanalization and retreatment, is not well established. The purposes of this study were to test the hypothesis that the FC is a significant factor for aneurysmal recurrence and to provide some insights on appropriate FC selection. METHODS The authors retrospectively reviewed endovascular coiling for 280 unruptured intracranial aneurysms and gathered data on age, sex, aneurysm location, aneurysm morphology, maximal size, neck width, adjunctive techniques, recanalization, retreatment, follow-up periods, total volume packing density (VPD), volume packing density of the FC, and framing coil percentage (FCP; the percentage of FC volume in total coil volume) to clarify the associated factors for aneurysmal recurrence. RESULTS Of 236 aneurysms included in this study, 33 (14.0%) had recanalization, and 18 (7.6%) needed retreatment during a mean follow-up period of 37.7 ± 16.1 months. In multivariate analysis, aneurysm size (odds ratio [OR] = 1.29, p < 0.001), FCP < 32% (OR 3.54, p = 0.009), and VPD < 25% (OR 2.96, p = 0.015) were significantly associated with recanalization, while aneurysm size (OR 1.25, p < 0.001) and FCP < 32% (OR 6.91, p = 0.017) were significant predictors of retreatment. VPD as a continuous value or VPD with any cutoff value could not predict retreatment with statistical significance in multivariate analysis. CONCLUSIONS FCP, which is equal to the FC volume as a percentage of the total coil volume and is unaffected by the morphology of the aneurysm or the measurement error in aneurysm length, width, or height, is a novel predictor of recanalization and retreatment and is more significantly predictive of retreatment than VPD. To select FCs large enough to meet the condition of FCP ≥ 32% is a potential relevant factor for better long-term outcomes. These findings support our hypothesis that the FC is a significant factor for aneurysmal recurrence.

Endovascular coiling of small intracranial aneurysms using a very soft bare platinum coil: A comparison of the packing performance of new and old HyperSoft® helical coils

AIMS

Soft and small coils are known to be appropriate for the treatment of small aneurysms. The purpose of this study was to determine whether the new HyperSoft® helical coil, which is softer and smaller than its predecessors, has any effect on the packing performance in a matched-pair study with an old HyperSoft® helical coil.

MATERIALS AND METHODS

Thirty-six consecutive patients harboring 43 cerebral aneurysms treated with new HyperSofts were included in this study. Forty-one aneurysms treated with old HyperSofts were identified from our database as matched controls based on similar volumes and locations. Packing attenuation, adverse events during the procedures, and angiographic occlusions were observed and compared between the two groups.

RESULTS

The mean packing density was significantly higher in the new HyperSoft® group compared to the control group (35.5% vs. 26.9%), and a larger proportion of the aneurysms embolized with the 1.5 mm size coil, which has higher packing density. There was no difference in immediate and midterm angiographic outcomes. There was no difference in the rate of intraprocedural perforation, but there was no intraprocedural rupture related to the 1.5 mm coil.

CONCLUSIONS

The use of new HyperSoft® helical coils allows higher packing density comparable with the old technology. New HyperSoft® coils, especially those with 1.5 mm loop diameter, can be expected to fill smaller residual spaces in small aneurysms and may be helpful in preventing recanalization.

Coil Embolization of Wide-Neck Bifurcation Aneurysms Using a Single-Balloon Microcatheter

BACKGROUND

Coil embolization of wide-neck cerebral aneurysms frequently requires stent or balloon assistance. Such approaches to coil embolization increase the procedural complexity, adding risk and cost.

OBJECTIVE

To describe a series of coil embolization procedures performed using a single-balloon microcatheter to treat wide-neck aneurysms and establish the safety, feasibility and efficacy of this technique.

METHODS

A retrospective review was performed to identify cases in which the Ascent balloon (Codman Neurovascular, Raynham, Mass., USA) was used as a single-balloon microcatheter for aneurysm coil embolization at two institutions. Clinical, demographic and angiographic data were obtained, and aneurysm volumes as well as packing densities (PD) were calculated.

RESULTS

Eight cerebral aneurysms were treated using this technique. Six of these were unruptured. The aneurysms had an average neck diameter of 3.7 mm, and the maximum dimension ranged from 5 to 11 mm, with a mean of 7.5 mm. The mean aspect ratio was 2.07. The mean volume of the aneurysms was 180.38 mm(3). The average PD achieved in these 8 aneurysms was 41.79%. Complete occlusion with coil embolization [Raymond-Roy Occlusion Classification (RROC) 1] was achieved in all cases except one, where a small residual was left deliberately and the occlusion grade was RROC 2. There were no intraprocedural complications.

CONCLUSION

This initial experience demonstrates the feasibility and immediate outcomes of a single-balloon microcatheter technique in coil embolization of wide-neck cerebral aneurysms. This technique may be used to achieve a high PD, comparable to that obtained with stent-assisted coiling or coiling alone, while avoiding permanent stent placement and potentially reducing thromboembolic complications.

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.

Use of a new soft and long coil reduces the number of coils to embolize a small aneurysm

BACKGROUND

In embolizing a cerebral aneurysm, achievement of a high-volume embolization ratio (VER: volume of inserted coils / aneurysm volume) is important because it may prevent coil compaction and recanalization. The goal of the study is to examine whether use of softer and longer coils gives an adequate VER with fewer coils, particularly for small aneurysms.

METHODS

Aneurysm volumes, VERs, and numbers of inserted coils were investigated in 23 cases of small aneurysms embolized using Infini coils, a long soft coil with a primary diameter of 0.010 inches (Infini group). An aneurysm volume- and VER-matched control (non-Infini) group of 59 cases was selected from patients treated at our facility. Data were also compared between subgroups of patients (n = 18 and n = 34 in the Infini and non-Infini groups, respectively) who were not treated with thicker coils with primary diameters of 0.0135-0.015 inches (18-type coils), since these coils affect the number of coils by increasing VER rapidly.

RESULTS

Average aneurysm volumes and VERs did not differ significantly between the Infini and non-Infini groups. Significantly fewer coils were used per 0.1 ml aneurysm volume in the Infini group (4.08 coils in average) compared with the non-Infini group (5.67) (p < 0.001). In the non-18-type subgroups, the number of coils used remained significantly smaller in the Infini group (4.49) compared with the non-Infini group (6.72), (p < 0.001).

CONCLUSION

To achieve VER ≥20%, use of Infini coils significantly decreased the number of coils required per unit volume of a small aneurysm.

Use of Hydrocoil in small aneurysms: procedural safety, treatment efficacy and factors predicting complete occlusion

Coil technology has been directed to reduce recurrence rates and we have seen the introduction of trials comparing the efficacy of surface modified versus bare platinum coils (BPC). This article reports on one treatment strategy in the treatment of small aneurysms by the placement of Hydrocoil across the neck of the aneurysm. Procedural safety, treatment efficacy and factors which predict complete occlusion are evaluated. We retrospectively identified a subgroup of small aneurysms treated over a four-year period. Analysis comparing aneurysms treated with Hydrocoil and BPC versus Hydrocoil alone was undertaken. Eighty-five aneurysms were coiled; 62% with Hydrocoil alone, 38% in combination with BPC. At six-month follow-up, overall 50% were completely occluded, 39.5% had a neck remnant and 10.5% had a residual aneurysm. Complete occlusion was identified in 39% in the Hydrocoil and BPC group compared to 56% in the Hydrocoil alone group. In 56/76 (74%) cases analysed, Hydrocoil loop successfully bridged the neck of the aneurysm in which 38/76 (68%) of these were completely occluded at six-month follow-up. Thirteen procedure-related complications occurred. Aneurysms treated with Hydrocoil alone resulted in fewer recurrences compared with a combination of Hydrocoil and BPC. These data suggest that the technique of positioning Hydrocoil at the neck of the aneurysm increases the probability of complete occlusion and is therefore a strong predictor of aneurysm occlusion. In our experience, this technique did not demonstrate an increased risk of intra-procedural rupture or thrombo-embolic complications compared to conventional embolization with BPC.

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

BACKGROUND AND PURPOSE

In 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 METHODS

Thirty-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.

RESULTS

Among 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%.

CONCLUSIONS

We can achieve a better outcome if size and volume of the aneurysm sac is smaller and if CPD is higher.

Endovascular treatment of intracranial aneurysms with detachable coils: correlation between aneurysm volume, packing, and angiographic recurrence

BACKGROUND AND PURPOSE

The relationship between dense packing and incidence of angiographic recurrence after endovascular treatment of intracranial aneurysms has been shown but remains controversial. We retrospectively analyzed intracranial aneurysms treated with detachable coils to determine the relation between aneurysm volume, packing, and recurrence.

METHODS

We reviewed 221 aneurysms in 199 patients who underwent endovascular coiling using detachable coils from November 2009 to December 2011. Aneurysm volumes were determined using three-dimensional images obtained from rotational angiography. Aneurysm packing was defined as the ratio between the volume of coils inserted and the volume of aneurysm. At follow-up, angiographic results were dichotomized into presence or absence of recurrence. The relationship between aneurysm volume to fill, packing, and angiographic recurrence was determined by multivariable logistic regression.

RESULTS

Follow-up angiography (mean follow-up 8.8 months) revealed recurrence in 14.5% of the aneurysms studied in our series. Recurrent aneurysms had a mean packing of 15.1% while stable aneurysms (non-recurrent) had a mean packing of 23.7%. Multivariable logistic regression analysis showed that aneurysm volume and packing were significantly associated with angiographic recurrence. Large volume aneurysms (>600 mm(3)) were found to have a higher incidence of recurrence than those with small volumes (OR=30.49, p<0.001). Compared with those with high packing (≥20%), the less packed aneurysms (<20%) had a higher incidence of recurrence (OR=29.01, p=0.002). There was no significant difference between aneurysm location, clinical presentation, stent assistance, duration of follow-up, and recurrence.

CONCLUSIONS

Coiling large volume (>600 mm(3)) intracranial aneurysms are more likely to have a recurrence than small ones. High packing (≥20%) provides better protection against recurrence of the aneurysm.

Reappraisal of anatomic outcome scales of coiled intracranial aneurysms in the prediction of recanalization

Objective

Several scales are currently used to assess occlusion rates of coiled cerebral aneurysms. This study compared these scales as predictors of recanalization.

Methods

Clinical data of 827 patients harboring 901 aneurysms treated by coiling were retrospectively reviewed. Occlusion rates were assessed using angiographic grading scale (AGS), two-dimensional percent occlusion (2DPO), and volumetric packing density (vPD). Every scale had 3 categories. Followed patients were dichotomized into either presence or absence of recanalization. Kaplan-Meier analysis was conducted, and Cox proportional hazards analysis was performed to identify surviving probabilities of recanalization. Lastly, the predictive accuracies of three different scales were measured via Harrell's C index.

Results

The cumulative risk of recanalization was 7% at 12-month, 10% at 24-month, and 13% at 36-month of postembolization, and significantly higher for the second and third categories of every scale (p<0.001). Multivariate-adjusted hazard ratios (HRs) of the second and third categories as compared with the first category of AGS (HR : 3.95 and 4.15, p=0.004 and 0.001) and 2DPO (HR : 4.87 and 3.12, p<0.001 and 0.01) were similar. For vPD, there was no association between occlusion rates and recanalization. The validated and optimism-adjusted C-indices were 0.50 [confidence (CI) : -1.09-2.09], 0.47 (CI : -1.10-2.09) and 0.44 (CI : -1.10-2.08) for AGS, 2DPO, and vPD, respectively.

Conclusion

Total occlusion should be reasonably tried in coiling to maximize the benefit of the treatment. AGS may be the best to predict recanalization, whereas vPD should not be used alone.

Long-term outcomes of coil packing for visceral aneurysms: correlation between packing density and incidence of coil compaction or recanalization

PURPOSE

To evaluate the correlation between packing density and the incidence of coil compaction or recanalization of visceral artery aneurysms (VAAs) after coil packing.

MATERIALS AND METHODS

Between July 2004 and April 2012, coil packing was performed for 46 true visceral aneurysms (16 splenic, 11 pancreaticoduodenal, eight renal, six hepatic, three superior mesenteric, one right gastric, and one gastroepiploic) in 42 patients. The size and volume of the aneurysm, packing density, and the incidences of compaction and recanalization were evaluated retrospectively.

RESULTS

The mean follow-up period was 37 months ± 8 (range, 11-80 mo). The mean packing density was 19% ± 8 (range, 5%-42%), mean aneurysm size was 19 mm ± 8 (range, 5-40 mm), and mean volume was 4,108 mm(3) ± 5,435 (range, 72-26,235 mm(3)). Compaction and recanalization occurred in two (4%) and 12 aneurysms (26%), respectively. The mean packing density was significantly lower in aneurysms with compaction or recanalization than in unaffected aneurysms (12% vs 22%; P = .00014). There was a significant difference in mean packing density between small (< 20 mm; 22%) and large (≥ 20 mm) aneurysms (15%; P = .0045). The mean size and volume were significantly larger for coil-compacted or recanalized aneurysms than for unaffected aneurysms (P < .05). In aneurysms with a packing density of at least 24%, no compaction or recanalization occurred.

CONCLUSIONS

Coil compaction or recanalization after coil packing for VAAs more often occurs after insufficient embolization with low packing density and in patients with large aneurysms.

Evaluation of contrast-enhanced MR angiography in the follow-up of visceral arterial aneurysms after coil embolization

BACKGROUND

The placement of detachable coil has become the alternative method of treating visceral arterial aneurysms (VAAs). Imaging follow-up is necessary after coil embolization because of frequent incomplete occlusion.

PURPOSE

To compare contrast-enhanced magnetic resonance angiography (CE-MRA) at 3T with a reference standard of digital subtraction angiography (DSA) for the evaluation of VAAs after coil embolization.

MATERIAL AND METHODS

We treated 15 patients with VAA with coil embolization; eight had splenic artery aneurysms and seven had renal artery aneurysms. We packed the aneurysmal sac preserving native arterial circulation. For follow-up, all patients underwent CE-MRA at 3T and DSA. The results were classified according to coil occlusion: Class 1, complete occlusion; Class 2, residual neck; Class 3, aneurysmal filling.

RESULTS

CE-MRA revealed 11 complete occlusions and four residual necks. DSA follow-up showed 12 complete occlusions and three residual necks. No aneurysmal filling occurred after treatment. Comparison of CE-MRA and DSA findings showed 93% agreement (14/15). CE-MRA allowed the detection of a residual neck in one misclassified case in which DSA showed occlusion. Coil-related artifacts were minimal and did not interfere with evaluation of the occlusion status of the VAAs.

CONCLUSION

CE-MRA at 3T provides high-quality images equivalent to DSA for the evaluation of VAAs after coil embolization. We suggest that CE-MRA at 3T might be used as the primary method for follow-up of VAAs after coil embolization.

Computational fluid dynamic analysis following recurrence of cerebral aneurysm after coil embolization

Hemodynamic factors are thought to play important role in the initiation, growth, and rupture of cerebral aneurysms. However, hemodynamic features in the residual neck of incompletely occluded aneurysms and their influences on recanalization are rarely reported. This study characterized the hemodynamics of incompletely occluded aneurysms that had been confirmed to undergo recanalization during long-term follow-up using computational fluid dynamic analysis. A ruptured left basilar-SCA aneurysm was incompletely occluded and showed recanalization during 11 years follow-up period. We retrospectively characterized on three-dimensional MR angiography. After subtotal occlusion, the flow pattern, wall shear stress (WSS), and velocity at the remnant neck changed during long-term follow-up period. Specifically, high WSS region and high blood flow velocity were found near the neck. Interestingly, these area of the remnant neck coincided with the location of aneurysm recanalization. High WSS and blood flow velocity were consistently observed near the remnant neck of incompletely occluded aneurysm, prone to future recanalization. It will suggest that hemodynamic factors may play important roles in aneurismal recurrence after endovascular treatment.

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.

Comparison of cerebral aneurysm volumes as determined by digitally measured 3D rotational angiography and approximation from three diameters

This study compared digital measurement of aneurysm volume by 3D rotational angiography (3D-RA) with an approximation technique using three diameters of an aneurysm to re-interpret previously reported optimal packing densities (volume embolization ratio, VER) in coil embolization of intracranial aneurysms. Estimation of the volume of saccular aneurysms is important for calculation of the VER, which is in turn reported to be useful for prediction of coil compaction. The conventional formula for the volume estimation is V=4/3 π(A/2) (B/2) (C/2), where A, B, and C are the aneurysmal height, length, and width measured on 3D-RA image respectively. Using 3D rotational angiography data from 74 aneurysms, the approximated volume generated using the conventional formula was directly compared with the digitally measured volume. The digitally measured volume varied from 0.003 ml to 7.935 ml, and the dome-to-neck ratio (D/N) from 0.79 up to 4.62. We found that the conventional formula almost systematically underestimated the volume by up to 50 %, particularly when the neck was large relative to the dome (D/N<2). On average, digitally measured volume was 1.26~1.29 times larger than the approximated volume obtained using the conventional formula.Conventional 2D angiography based aneurysm volume calculation tends to underestimate an aneurysm volume, so the so-called VER (volume embolization ratio) could be overestimated.

Unusual cisternal coil migration in the follow-up period after aneurysm perforation during endovascular coiling

A 61-year-old woman suffered cisternal coil migration in the follow-up period after endovascular coil embolization for a ruptured cerebral aneurysm. She presented with sudden onset of headache. Computed tomography demonstrated diffuse subarachnoid hemorrhage, and cerebral angiography disclosed a left anterior choroidal artery aneurysm. The aneurysm was treated by endovascular embolization with Guglielmi detachable coils. During the embolization procedure, the microcatheter perforated the aneurysm. For direct closure of the perforation site with coils, the microcatheter was withdrawn and coils were deployed partially in the subarachnoid space and partially in the aneurysm sac. The coil mass was spread in the subarachnoid space around the aneurysm immediately after embolization. The patient was discharged with no neurological deficit. Three months later, follow-up radiography demonstrated obvious reduction in the size and compaction of the coil mass. Magnetic resonance angiography and digital subtraction angiography demonstrated stable occlusion of the aneurysm. The coil mass probably spread in the cistern around the aneurysm and was compacted by the shape memory of the coils and pulsation of the brain and vessels, as the subarachnoid clots around the aneurysm had disappeared. This case suggests that cisternal coil migration should be considered in the follow up of intracranial aneurysm treated with detachable coils.

Early ceasing of intra-aneurysmal contrast opacification during coil embolization in ruptured aneurysms compared with unruptured aneurysms

BACKGROUND

The difference between coil-embolized ruptured and unruptured aneurysms with respect to intra-aneurysmal thrombus formation remains to be determined.

OBJECTIVE

We examined whether there was a difference between ruptured and unruptured coil-embolized aneurysms in the rate and timing of thrombus formation in the aneurysmal sac and discuss the effect of thrombus on the treatment outcome.

METHODS

We evaluated 209 aneurysms with an aneurysmal dome smaller than 10 mm and a neck size less than 4 mm. Of these, 91 (43.5%) were ruptured. We assessed intra-aneurysmal thrombus formation by the coil-packing ratio (CPR): the percentage of coil volume occupying the aneurysmal sac. The initial CPR was defined as the CPR at which contrast influx into the sac ceased and the final CPR as that at the end of the procedure. ΔCPR was calculated as the difference between initial and final CPRs. Embolized aneurysms were evaluated on follow-up angiograms.

RESULTS

The initial CPR was significantly lower in ruptured aneurysms (P < .01), and there was not a significant difference in the final CPR between ruptured and unruptured aneurysms (P = .05). ΔCPR was significantly higher in ruptured aneurysms (P < .01). The rate of aneurysmal recanalization was significantly higher in ruptured aneurysms (P < .05). The incidence of recanalization was high in ruptured aneurysms with low initial CPR and ΔCPR values.

CONCLUSION

In ruptured aneurysms, intra-aneurysmal thrombus formation tends to occur in the earlier stages of coil embolization. In some cases, thrombus formation may inhibit dense coil packing and result in recanalization.

High shear stress and flow velocity in partially occluded aneurysms prone to recanalization

BACKGROUND AND PURPOSE

Hemodynamic factors are thought to play an important role in the initiation, growth, and rupture of cerebral aneurysms. However, the hemodynamic features in the residual neck of the partially embolized aneurysms and their influences on recanalization are rarely reported. In this study, we characterized the hemodynamics of partially occluded aneurysms, which were proven to undergo recanalization during follow-up using computational fluid dynamic analysis.

METHODS

From May 2007 to June 2009, we identified 11 partial aneurysms during follow-up, including 5 recanalized cases and 6 stable cases with 3-dimensional digital subtraction angiography. We retrospectively characterized the hemodynamic features around the residual aneurysmal pouch using the available postprocedural digital subtraction angiography image data. The occluded part of the aneurysm was regarded as completely separated from the circulation.

RESULTS

The overall blood flow patterns before embolization were almost the same in the recanalized and stable groups. After occlusion, the flow pattern changes, wall shear stress (WSS), and velocity at the remnant neck demonstrated different changes between the 2 groups. Specifically, in the recanalized group, high WSS regions were found near the neck in all 5 cases, with 4 of them being even higher than those before occlusion. Interestingly, in all cases, the high WSS area of the remnant neck coincided with the location where the aneurysm recanalization occurred. In the stable group, 5 out of 6 cases demonstrated lower WSS and velocity at the remnant neck after occlusion.

CONCLUSIONS

High WSS and blood flow velocity were consistently observed near the remnant neck of partially embolized aneurysms prone to future recanalization, suggesting that hemodynamic factors may have an important role in aneurysmal recurrence after endovascular treatment. The difference in flow pattern could be caused by the incomplete occlusion of the aneurysms.

Histomorphology of thrombus organization, neointima formation, and foreign body response in retrieved human aneurysms treated with hydrocoil devices

Biological processes, such as thrombus organization, endothelialization, and foreign body response, that occur following embolization of intracranial aneurysms are poorly understood. We examined 13 human aneurysms (retrieved at autopsy 1-74 days postembolization) treated with hybrid hydrogel-platinum coil devices and platinum coils. The specimens were embedded in methyl methacrylate and ground sections were surface stained. Using light microscopy, thrombus organization in the sac, endothelialization of the neck, and foreign body response to the embolic devices were determined. The area percentages of the sac occupied by embolic devices and unorganized thrombus were quantified using image analysis. Thrombus organization increased over time, but was incomplete up to 74 days post-treatment. Neointima formation had started at 5 days upon dense fibrin depositions and progressed to form a new vessel wall at 74 days. The foreign body response to the hydrogel was characterized by mononuclear macrophages, while platinum coils were surrounded by multinuclear foreign body giant cells. Histometric aneurysm occlusion ranged from 89 to 100% and embolic devices occupied 31-64% of the aneurysm sac. These findings showed that the hydrogel-based devices occupied a large percentage of the aneurysm sac, provided a framework for thrombus organization to occur, and elicited less severe foreign body response than platinum coils.

Unusual delayed hydrocephalus after bare platinum coil embolization of an unruptured aneurysm

A 69-year-old woman developed hydrocephalus after the embolization of an incidentally detected unruptured large internal carotid artery aneurysm with bare platinum coils. Endovascular embolization resulted in near-total aneurysm occlusion. She complained of mild headache 18 hours after the procedure and magnetic resonance (MR) imaging performed on the 6(th) post-treatment day revealed wall enhancement and perianeurysmal brain edema. Follow-up MR imaging showed recanalization of the aneurysm and gradual ventricular enlargement. She presented with typical symptoms of hydrocephalus including disorientation, gait disturbance, and urine incontinence at 7 months post-embolization. We removed 30 ml of cerebrospinal fluid by lumbar tap, which improved her condition without symptom recurrence for 2 months. She did not require shunt placement. Post-interventional hydrocephalus is known in patients with unruptured aneurysms embolized with bioactive second-generation coils. This case shows that hydrocephalus can occur after aneurysm embolization with bare platinum coils without intracranial hemorrhage.

Evaluation of the characteristics of various types of coils for the embolization of intracranial aneurysms with an optical pressure sensor system

INTRODUCTION

In coil embolization for an intracranial aneurysm, it is important to appropriately choose the coil most suitable for coping with various unforeseen situations. Additionally, because dense coil packing of the aneurysm sac is the most important factor to avoid a recurrence, properly selecting the coil is essential. In this article, the authors measured the coil insertion pressure of various types of coils with a newly developed sensor system, and coil characteristics were investigated.

METHODS

The sensor consists of a hemostatic valve connected to the proximal end of a microcatheter. The sensor principle is based on an optical system. Using this, an experimental silicone aneurysm embolization was performed automatically at constant speed. The pattern of the insertion pressure and the maximum insertion pressure (MIP) were analyzed for the various types of coils. The sensor continuously monitored the mechanical force during the insertions.

RESULTS

The sensor adequately recorded the coil insertion pressure during embolization in each coil. MIP was generally ranked in order of the coil type. The soft type coils required relatively less insertion pressure than standard/helical and 3D type. As for the patterns of coil insertion pressure, each coil presented a saw-like pressure pattern, though we observed some slight differences. 3D type coils showed peak pressure at the moment of "painting". Coil loop diameters barely affected MIP. However, as to the patterns of pressure, larger size coils more often presented the peak.

CONCLUSIONS

Coil characteristics were well evaluated. The results obtained here reflected some actual clinical experience. Furthermore, collecting the in vivo study is mandatory, which may provide clinically useful data.

The effectiveness and feasibility of endovascular coil embolization for very small cerebral aneurysms: mid- and long-term follow-up

BACKGROUND

Endovascular embolization for very small cerebral aneurysms (VSCAs) is still controversial. We report our experience with endovascular coil embolization for these lesions and assess the feasibility and effectiveness.

METHODS

We conducted a review of our experience with endovascular treatment of a series of 19 patients with 20 VSCAs, located at the supraclinoid segment of the internal cranial artery (ICA) in seven, the cavernous ICA segment in three, the anterior communicating artery in five, vertebral artery-posterior inferior cerebellar artery in two, bifurcation of the middle cerebral artery in one, the pericallosal artery in one, and the P2 segment in one. The World Federation of Neurosurgical Societies classification before treatment was grade I in 14 patients and grade II in five patients. The strategy of endovascular treatment included coil occlusion, balloon-assisted coiling, and stent-assisted coiling. Occlusion rate was divided into (1) total/near total, occlusion rate 95-100%; (2) subtotal, occlusion rate 80-95%; and (3) partial, occlusion rate<80%. Clinical outcome of patients with ruptured aneurysm was ascertained according to the Glasgow Outcomes Scale.

RESULTS

All patients were successfully treated with coil embolization; immediate angiography determined occlusion of the aneurysm, including total occlusion in five, subtotal occlusion in nine, and partial occlusion in six. During 1-2 years of follow-up, all aneurysms were confirmed as complete occlusion by control angiography. No recurrence or coil compaction occurred. No rehemorrhage or ischemic stroke occurred.

CONCLUSION

Endovascular coil embolization for VSCAs is effective and feasible. Initial subtotal or partial aneurysm occlusion might progress to total occlusion.

A comparison of experimental aneurysm occlusion determination by angiography, scanning electron microscopy, MICROFIL perfusion, and histology

In clinical practice, occlusion of embolized, intracerebral aneurysms is evaluated using angiography. Standard, two-dimensional digital subtract angiography (DSA) is unable to quantify irregular aneurysm remnants, and even three-dimensional rotational angiography cannot quantify the degree of occlusion. To better understand occlusion at the aneurysm neck, we compared angiographic results with MICROFIL perfusion, histology, and scanning electron microscopy (SEM) results in 20 elastase-induced saccular aneurysms in rabbits. Aneurysms were embolized with HydroCoil devices (n = 12) or platinum coils (n = 8). Aneurysm follow-up occurred at 2 (n = 10) and 6 (n = 10) weeks. Aneurysm occlusion was evaluated using DSA, MICROFIL perfusion, histological ground sections, and SEM. Groups were compared statistically using ANOVA and chi(2) tests. The MICROFIL perfusion results were not concordant with the angiographic results for the HydroCoil and platinum coil groups. Both increased and decreased occlusion was observed on the MICROFIL-perfused aneurysms when compared with angiography. The histologic occlusion results of the HydroCoil group were concordant with the angiographic results; however, unoccluded areas not visible on angiography were routinely observed on the ground sections in the platinum coil group. SEM imaging of the aneurysm neck consistently showed decreased occlusion than angiographic results for both the HydroCoil and platinum coil groups. Although histology and MICROFIL-perfusion analyses provided additional details of aneurysm occlusion when compared with angiography, complete visualization of the entire neck of the aneurysm and accurate assessment of aneurysm occlusion was possible only with SEM.

Angiographic and clinical outcomes in 200 consecutive patients with cerebral aneurysm treated with hydrogel-coated coils

BACKGROUND AND PURPOSE

Denser coil packing in intracranial aneurysms is believed to result in lower recanalization rates. Hydrogel-coated expandable coils (HydroCoil) improve volumetric packing of aneurysms in animal models and clinical studies, but data from large clinical series are limited. The objective of this retrospective analysis was to analyze immediate and follow-up angiographic results as well as complications in a large consecutive series of patients treated with HydroCoils at a single institution.

MATERIALS AND METHODS

Retrospective analysis was performed of periprocedural complications, immediate and follow-up angiograms, and retreatments of the first 200 consecutive intracranial aneurysms treated at Emory University Hospital.

RESULTS

One hundred eighty-seven patients with 200 intracranial aneurysms were treated with HydroCoils during a 3-year period. Immediate angiograms showed complete aneurysmal obliteration in 58.4% of small aneurysms and 42.7% of large aneurysms. Periprocedural complications included early rebleeding and thromboembolic events resulting in permanent neurologic morbidity and mortality in 6% of cases. Follow-up angiography during an average of 16.3 months demonstrated recanalization in 17.7% of small aneurysms and 28.6% of large aneurysms, requiring retreatment in 6.3% and 19.0% of cases, respectively. During the same time period, there was delayed angiographic improvement in aneurysm obliteration in 26.6% of small aneurysms and 26.2% of large aneurysms.

CONCLUSIONS

First-generation HydroCoil treatment of intracranial aneurysms has a favorable rate of recanalization compared with most large series of pure platinum coils with similar complication rates.

Coiling of intracranial aneurysms: a systematic review on initial occlusion and reopening and retreatment rates

BACKGROUND AND PURPOSE

The proportion of incompletely occluded aneurysms after coiling varies widely between studies. To assess overall outcome of coiling, we systematically reviewed the literature to determine initial occlusion, reopening, and retreatment rates of coiled aneurysms according to predefined criteria and subgroups.

METHODS

We searched PubMed and EMBASE (January 1999 to September 2008) for studies of >50 coiled aneurysms. Two reviewers independently extracted data. We grouped studies reporting on only ruptured aneurysms, posterior circulation aneurysms, and studies with large proportions of aneurysms >10 mm to assess possible determinants for incomplete occlusion, reopening, and retreatment.

RESULTS

Forty-six studies totalling 8161 coiled aneurysms met inclusion criteria. Immediately after coiling, 91.2% (95% CI, 90.6% to 91.9%) of the aneurysms were adequately occluded. Aneurysm reopening occurred in 20.8% (95% CI, 19.8% to 21.9%) and retreatment was performed in 10.3% (95% CI, 9.5% to 11.0%). Reopening rate was lower in studies reporting on ruptured aneurysms only compared with all studies (11.4% versus 20.8%; relative risk, 0.55; 95% CI, 0.47 to 0.64) and higher in studies focusing on posterior circulation aneurysms compared with studies with >85% anterior circulation aneurysms (22.5% versus 15.5%; relative risk, 1.5; 95% CI,1.2 to 1.7). Regression analysis showed higher retreatment rates with increasing proportion of aneurysms >10 mm (beta=0.252; 95% CI, 0.073 to 0.432). We could not find a relation between reopening and type of coils used.

CONCLUSIONS

At follow-up, one fifth of all coiled intracranial aneurysms shows reopening of which half is retreated. Possible risk factors for aneurysm reopening are location in the posterior circulation and size >10 mm. To confirm our findings, a meta-analysis on individual well-reported patient data is desirable.

Angiographic and histologic comparison of experimental aneurysms embolized with hydrogel filaments

BACKGROUND AND PURPOSE

The embolization of aneurysms with hydrogel filaments allow postprocedural CT and MR imaging studies without artifacts. We compared the performance of 3 hydrogel filament formulations in rabbit experimental aneurysms by using angiography and histologic samples.

MATERIALS AND METHODS

Embolization of 35 rabbit elastase or bifurcation aneurysms was performed with 3 different formulations of detachable hydrogel filaments, including 1) polyethylene glycol opacified with aromatic iodine (PEG-I; n = 12), 2) polyethylene glycol opacified with barium sulfate (PEG-B; n = 12), or 3) polypropylene glycol opacified with barium sulfate (PPG-B; n = 11). Follow-up angiography was performed before the rabbits were killed at 2 (n = 7), 6 (n = 9), 10 (n = 8), or 26 (n = 11) weeks. Angiographic occlusion was scored according to the Raymond scale, and interval changes were assessed. The harvested aneurysms were evaluated on histologic examination. From the sections, we determined the percentage of the sac excluded from the vasculature and occupied by embolic devices by using image analysis. We compared results using the analysis of variance/t test or chi(2) test.

RESULTS

The mean number of devices used to treat aneurysms in the PPG-B group was significantly greater than that used for the other 2 groups, though aneurysm volumes were similar among groups. Compared with immediate posttreatment occlusion scores, mean angiographic occlusion at follow-up was increased for all 3 hydrogel filament groups. On histologic examination, thrombus organization, neointima formation, and inflammation were similar to that observed in rabbit experimental aneurysms with other embolic devices containing platinum coils.

CONCLUSIONS

The embolization of experimental aneurysms with hydrogel filaments resulted in durable angiographic and histologic occlusion from 2 to 26 weeks. With improvements, hydrogel filaments free from metallic coils show promise for endovascular use.

Early Rebleeding of Small Anterior Communicating Artery Aneurysm with Presumed Extrusion of Coil Loop to Outside the Aneurysmal Wall during Endovascular Treatment. A Report of Two Cases

SUMMARY

Although endovascular treatment has been proved to be as effective as surgical clipping in the prevention of rebleeding of ruptured aneurysm, early rebleeding after coil embolization has seldom been reported. We experienced early rehemorrhage in two patients of ruptured small anterior communicating artery aneurysms of complete treatment with coil-embolization initially. In both cases what interested us was not early rebleeding itself but how the presumed extrusion of the first part of coil loop beyond aneurysmal wall developed. However, there was no evidence of intraprocedural rupture and moreover complete occlusion with only one or two coils was obtained. Our two patients underwent successful second treatment. We discovered the presumed extruded first part of the coil loop initially was located inside the enlarged aneurysmal sac in retreatment stage. In case of coil embolization of ruptured small anterior communicating aneurysm, the phenomenon we experienced with no evidence of intraprocedural rupture in spite of obvious extrusion of coil loop beyond the aneurysmal wall can be a sign of necessity for early follow-up study including plain radiography to track the change in the presumed extruded coil loop.

Endovascular Treatment for Very Small Supraclinoid Aneurysms with Stent-Assisted Coiling. Long-Term Follow-up in Six Cases

SUMMARY

The endovascular treatment of very small aneurysms (lesions less than 3 mm in maximum diameter) with wide necks remains a challenge for saccular embolization. We retrospectively analyzed our data using Neuroform stent-assisted coiling for very small supraclinoid aneurysms with wide neck to evaluate the feasibility and efficacy of endovascular treatment of these lesions. We conducted a review of our experience and results of endovascular treatments in six patients with seven very small aneurysms. All aneurysms were located at the side wall of the supraclinoid segment of the ICA. They were ruptured in two patients and unruptured in four. The technique of stent-assisted coiling was used in all cases with coiling before stenting and additional coils after deployment of the stent in the same session. All patients were successfully embolized with stent-assisted coiling. The coils were introduced into the lumen for subtotal occlusion in five aneurysms and for partial occlusion in two. During one to two years follow-up angiography, all aneurysms were completely occluded and no recurrence occurred. No complications were observed. Endovascular stent-assisted coil embolization of supraclinoid very small aneurysms with wide necks is effective and feasible. Subtotal aneurysm occlusion might progress to total occlusion.

Spanish Registry for Embolization of Small Intracranial Aneurysms with Cerecyte Coils (SPAREC) Study. Early Experience and Mid-Term Follow-up Results

SUMMARY

This study aimed to report the results obtained in treating small ruptured and unruptured intracranial aneurysms using Cerecyte coils. A prospective, non-randomized multicenter registry operating in Spain with a reporting period between May 2005 and September 2007.We present clinical and angiographic results for 48 small aneurysms (26 ruptured, five with III cranial nerve paresis, and 17 incidental) that had undergone six months' follow-up. The volumetric percentage occlusion (VPO) achieved and percentage bioactive coils (PBC) used were assessed. No episodes of bleeding occurred during the follow-up period. The technical complication rate was 10.4% (five cases): four thromboembolic complications resolved with medication (8.3%) and one asymptomatic protrusion of a coil into the parent vessel. The clinical complication rate for the procedure was 2.1% (occlusion of the anterior choroidal artery in a ruptured anterior choroidal anaeurysm). Mean VPO was 25.2%. Balloon-assisted technique (BAT) was used in 60.4% of cases. The VPO was higher in the BAT-treated cases (P < 0.05). The overall six-month recanalization rate was 16.7% (12.5% minor and 4.2% major recanalizations). Neck size and VPO were unrelated to the recanalization rate. The PBC was higher in cases with progressive Deployment of the device is safe from the standpoint of periprocedural technical and clinical complications. No episodes of hemorrhage were recorded during follow-up. The sixmonth recanalization and retreatment rates compared favorably with most endovascular platinum and bioactive coil series.

Endovascular treatment of tiny ruptured anterior communicating artery aneurysms

Introduction

Because of its high complication rate, the endovascular treatment (EVT) of anterior communicating artery (ACoA) aneurysms less than 3 mm in maximum diameter remains controversial. We evaluated EVT of tiny ruptured ACoA aneurysms with Guglielmi detachable coils (GDCs).

Methods

We treated 19 ruptured ACoA aneurysms with a maximum diameter of ≤3 mm with GDCs. The pretreatment Hunt and Hess score was grade 1 in four patients, grade 2 in six, grade 3 in six, and grade 4 in three. The patients were clinically assessed before and after treatment and with multiple angiographic follow-up studies.

Results

All EVTs were successful; there were no aneurysm perforations or any other treatment-related complications. In five patients older than 80 years the transfemoral approach was difficult, and the direct carotid approach was used. Complete and near-complete occlusion was achieved in 16 patients (84.2%) and 3 patients (15.8%), respectively. Of the 19 patients, 16 (84.2%) were followed angiographically for a median of 38.5 months (range 16–72 months). None demonstrated recanalization of the aneurysm requiring additional treatment. In 15 patients (78.9%) the final outcome was good (modified Rankin scale, mRS, score 0–2), and 3 patients (15.8%) died or suffered severe disability (mRS score 4–6). None of 18 patients who were followed clinically for a median of 39.5 months (range 17–84 months) experienced rebleeding.

Conclusion

Even tiny ruptured ACoA aneurysms can be safely treated by EVT by expert neurointerventionalists using advanced 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.