Coil Embolization Of Aneurysms Research Articles

Visual dysfunction and neurodegeneration caused by severe inflammatory optic neuropathy after coil embolization of a paraclinoid aneurysm: illustrative case.

Visual impairment due to delayed optic neuropathy is a rare complication of the endovascular treatment of paraclinoid aneurysms. An inflammatory response induced in the treated aneurysm wall is a known mechanism underlying this pathophysiology. The authors describe a case with severe and progressive optic neuropathy leading to neuronal degeneration and severe visual dysfunction. A 42-year-old female with a history of surgical clipping for a paraclinoid aneurysm presented with a recurrence. Although the patient was unaware of any visual dysfunction, a preoperative ophthalmological examination revealed mild inferior quadrantanopia in the left eye. The coil embolization procedure was uneventful; however, the following day, the patient experienced progressive visual impairment, which worsened despite the initiation of steroid therapy. Ophthalmological examination revealed a severe decrease in visual acuity and further deterioration of the visual field. Magnetic resonance imaging showed remarkable swelling and edema of the left optic nerve adjacent to the treated aneurysm. Despite continued steroid therapy, the patient's visual function did not recover well due to subsequent optic nerve degeneration. Optic neuropathy after endovascular procedures can lead to severe visual dysfunction. Careful management is essential, particularly when treating a symptomatic paraclinoid aneurysm, even if symptoms are only apparent on detailed examination.

Factors predicting recanalization following stent-assisted coil embolization of unruptured intracranial aneurysms with long-term follow-up.

Stents have been widely used for coil embolization for intracranial aneurysms. Few studies have analyzed the risk factors of recanalization through long-term follow-up observation of only stent-assisted coiling. We analyzed the risk factors for recanalization through long-term observations. A total number of 399 unruptured aneurysms treated by stent-assisted coil embolization between 2003 and 2016 in a single institution were analyzed for determining the factors associated with recanalization including the patient characteristics, aneurysms, and procedural variables. All patients underwent angiographic follow-up with digital subtraction angiography or magnetic resonance angiography at 24 months or more following the procedure. Recanalization occurred in 8%. The mean time for the recanalization was 21.1 ± 14.0 months (range, 5-51 months). The receiver operating characteristic curve analysis indicated areas under the curve for a maximum aneurysm size of 0.773 (cut-off, 6.415 mm). Multivariate analysis revealed that the maximum aneurysm size and parent artery curvature at which the aneurysm developed were significantly associated with recanalization. In parent artery curvature, the bifurcation group (OR, 9.02; 95% CI, 2.53-32.13; p = 0.001) and the convex group (OR, 3.68; 95% CI, 1.17-11.50; p = 0.025) were independent predictors of recanalization compared with the straight group. The maximum aneurysm size and parent artery curvature are risk factors associated with recanalization in stent-assisted coil embolization.

Safety and efficacy of the novel Alpha stent for the treatment of intracranial wide-necked aneurysm

The Alpha stent is an intracranial closed-cell stent with a unique mesh design to enhance wall apposition. It recently underwent structural modifications to facilitate easier stent deployment. This study aimed to evaluate the safety and efficacy of stent-assisted coil embolization for unruptured intracranial aneurysms using the Alpha stent. Between January 2021 and November 2021, 35 adult patients with 35 unruptured intracranial aneurysms in the distal internal carotid artery were prospectively enrolled. For efficacy outcomes, magnetic resonance angiography at the 6-month follow-up was evaluated using the Raymond-Roy occlusion classification (RROC). The safety outcome evaluated the occurrence of symptomatic procedure-related neurological complications up to 6 months postoperatively. Technical success was achieved in 34/35 (97.1%). Six months postoperatively, aneurysm occlusion showed RROC I in 32/35 (91.4%) and RROC II in 3/35 (8.6%) patients. Procedure-related neurologic complications occurred in one patient (2.9%) who experienced hemiparesis due to acute lacunar infarction, which resulted in a 6-month mRS score of 1. The Alpha stent demonstrated excellent efficacy and safety outcomes in stent-assisted coil embolization of unruptured distal ICA aneurysms. The recent structural modifications allowed for easier stent delivery and deployment.Clinical trial registration number: KCT0005841; registration date: 28/01/2021.

Evaluation of the shrinkage process of a neck remnant after stent-coil treatment of a cerebral aneurysm using silent magnetic resonance angiography and computational fluid dynamics analysis: illustrative case.

Silent magnetic resonance angiography (MRA) mitigates metal artifacts, facilitating clear visualization of neck remnants after stent and coil embolization of cerebral aneurysms. This study aims to scrutinize hemodynamics at the neck remnant by employing silent MRA and computational fluid dynamics. The authors longitudinally tracked images of a partially thrombosed anterior communicating artery aneurysm's neck remnant, which had been treated with stent-assisted coil embolization, using silent MRA over a decade. Computational fluid dynamics delineated the neck remnant's reduction process, evaluating hemodynamic parameters such as flow rate, wall shear stress magnitude and vector, and streamlines. The neck remnant exhibited diminishing surface area, volume, neck size, dome depth, and aspect ratio. Its reduction correlated with a decline in the flow rate ratio of the remnant dome to the inflow parent artery. Analysis delineated regions within the contracting neck remnant characterized by consistently low average wall shear stress magnitude and variation, accompanied by notable variations in wall shear stress vector directionality. Evaluation of neck remnants after stent-coil embolization is possible through silent MRA and computational fluid dynamics. Predicting the neck remnant reduction may be achievable through hemodynamic parameter analysis.

Safety of Local Anesthesia in Coil Embolization of Aneurysms: A Systematic Review and Meta-analysis (P3-5.003)

Safety of Local Anesthesia in Coil Embolization of Aneurysms: A Systematic Review and Meta-analysis (P3-5.003)

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

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). A total of 59 UIAs treated with a Neuroform Atlas stent were retrospectively analyzed. The WCS was identified on digital subtraction angiography (DSA) 1year 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. 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. 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.

Medulla and cervical cord contrast-induced encephalopathy detected by neuromonitoring during coil embolization of posterior circulation aneurysms.

Understanding the risks of contrast-induced encephalopathy (CIE), a serious complication of contrast agents, is crucial in endovascular treatment. We present the case of a 73-year-old woman who developed CIE in the medulla and cervical cord during coil embolization for unruptured left basilar-superior cerebellar artery and basilar artery tip aneurysms. The CIE was identified via neuromonitoring. In this case, spinal cord ischemia might have occurred due to reduced perfusion pressure after inserting the distal access catheter (DAC) in the vertebral artery. Multiple injections of contrast medium via the DAC during coil embolization likely contributed to an unusual form of CIE. Extreme caution is warranted during endovascular treatments involving the posterior circulation, due to the relatively high incidence of contrast-mediated encephalopathy, which can lead to severe consequences such as perforator infarction. Neuromonitoring is very useful for the early detection of neurological changes, particularly because intraoperative angiography may not reveal all irregularities.

Efficacy and safety of low profile stents in Y-stent assisted coil embolization of wide-necked bifurcation aneurysms: a systematic review and meta-analysis.

Low-profile stents may provide significant advantages in Y-stent-assisted coiling due to their miniaturized design and capability to be delivered through a 0.0165-inch microcatheter. We aim to investigate the safety and efficacy of using these newer versions of stents in Y-stent-assisted coiling for the treatment of wide-necked bifurcation aneurysms. We conducted a systematic review of the PubMed, Embase, Cochrane Library, and Web of Science databases up to September 2023, following the PRISMA guidelines. Eligible studies included  ≥ 5 patients with intracranial wide-necked bifurcation aneurysms treated with Y-stent-assisted coiling using low-profile stents, providing angiographic and clinical outcomes. Two authors independently handled the search and selection. Primary outcomes were immediate and follow-up aneurysm occlusion, procedure-related complications, aneurysm recanalization, and retreatment. Secondary outcomes included technical success, procedure-related morbidity, procedure-related mortality, procedure-related stroke, and in-stent stenosis at follow-up. We analyzed the data using random-effects meta-analysis. In total, 19 studies including 507 patients with 509 aneurysms were included. 95% of the treated aneurysms were managed using the crossing Y-configuration. Technical success rate was 99%. Immediate adequate aneurysm occlusion was 90%. Follow-up angiographies were available for 443 aneurysms. The mean angiographic follow-up duration was 15.6 ± 1.9 months. The rates for follow-up adequate aneurysm occlusion and complete occlusion were 98% and 89%, respectively. After a mean clinical follow-up of 15 ± 2.4 months, a good clinical outcome was observed in 98% of patients. Overall, procedure-related morbidity and mortality rates were 1.3%, and 0.4%, respectively. Low-profile stents in Y-stent-assisted coiling outperform previous stent versions in terms of safety, efficacy, and technical success rates.

Combination of neuroendoscopic hematoma evacuation and endovascular coil embolization for a ruptured anterior choroidal artery aneurysm in patients with moyamoya disease: illustrative cases.

The treatment strategy for hemorrhagic moyamoya disease (MMD) due to a ruptured aneurysm at the distal portion of the anterior choroidal artery remains controversial. The authors successfully treated the ruptured aneurysm with neuroendoscopic hematoma evacuation, followed by endovascular coil embolization. The authors encountered two patients with massive hemorrhagic MMD whose MMD had already been diagnosed and who had a periventricular anastomosis due to a ruptured aneurysm of the distal portion of the anterior choroidal artery involving the periventricular anastomosis. In both cases, neuroendoscopic hematoma evacuation was performed for hemorrhagic MMD in the acute phase, followed by endovascular coil embolization of the ruptured aneurysm in the chronic phase. In both endovascular treatments, the patient's condition was stabilized by hematoma evacuation, allowing a detailed preoperative evaluation of the anatomical findings of the vessel and functional findings of intraoperative neurophysiological monitoring using continuous monitoring of motor evoked potentials to preserve motor function. Combination therapy can be useful for hemorrhagic MMD in patients with diagnosed MMD with a periventricular anastomosis. Additionally, a preoperative understanding of the vascular construction and intraoperative neurophysiological monitoring will aid in the successful coil embolization of aneurysms at the distal portion of the anterior choroidal artery with hemorrhagic MMD.

Clopidogrel versus newer P2Y12 inhibitors in the dual antiplatelet therapy for stent-assisted coil embolization of intracranial aneurysms: A meta-analysis.

Stent-assisted coil embolization (SACE) for cerebral aneurysms requires dual antiplatelet therapy (DAPT), commonly clopidogrel plus aspirin is preferable to ticagrelor or prasugrel plus aspirin. However, there are few studies assessing the safety of the association of ticagrelor or prasugrel plus aspirin. Compare the safety of newer P2Y12 inhibitors with clopidogrel in patients that underwent a SACE for cerebral aneurysms. In accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines, we searched PubMed and Embase for studies comparing newer P2Y12 inhibitors with clopidogrel in patients undergoing DAPT for SACE. Outcomes were total number of complications, number of hemorrhagic complications, and number of thromboembolic complications both intraoperative and follow-up. A random effects model was used to calculate odds ratios (ORs) with 95% confidence intervals (CIs). We included 1026 patients from six studies. Newer P2Y12 inhibitors were used in 562 (54,77%) patients. There were no significant differences between groups in total number of complications (OR 0.80; 95% CI 0.32, 1.99; p < 0.01; I2 = 78%), in intraoperative hemorrhagic complications (OR 0.66; 95% CI 0.09, 4.71; p = 0.68; I2 = 0%), follow-up hemorrhagic complications (OR 1.23; 95% CI 0.70, 2.15; p = 0.49; I2 = 0%), intraoperative thromboembolic complications (OR 0.43; 95% CI 0.14, 1.35; p = 0.25; I2 = 24%), and in follow-up thromboembolic complications (OR 0.89; 95% CI 0.33, 2.39; p = 0.03; I2 = 59%). In patients who underwent a SACE, newer P2Y12 inhibitors showed no differences in intraoperative and follow-up complications compared with clopidogrel.

Endovascular occlusion of segmental arteries feeding the anterior spinal artery to stage endovascular thoracoabdominal aortic repair

ObjectiveMinimally invasive segmental artery coil embolization was introduced to prevent spinal cord ischemia after endovascular repair of thoracoabdominal aortic aneurysms. There is no consensus on whether the endovascular occlusion of segmental arteries feeding directly the anterior radiculomedullary artery and anterior spinal artery can be safely performed without causing spinal cord ischemia. Our aim was to investigate the feasibility and clinical impact of endovascular occlusion of segmental arteries supplying the anterior spinal artery during minimally invasive segmental artery coil embolization in patients with thoracoabdominal aortic aneurysms. MethodsBetween January 2018 and July 2020, 54 patients (36 male; mean age, 71.1 ± 9.3 years) underwent direct embolization of segmental arteries feeding the anterior radiculomedullary artery before endovascular repair of thoracoabdominal aortic aneurysms. End points included technical success of minimally invasive segmental artery coil embolization of segmental arteries, anterior radiculomedullary artery, neurological complications, and in-hospital mortality after minimally invasive segmental artery coil embolization and endovascular repair of thoracoabdominal aortic aneurysms. ResultsThe thoracoabdominal aortic aneurysm classification was type I (n = 8), type II (n = 24), type III (n = 11), and type IV (n = 11). During minimally invasive segmental artery coil embolization, 388 segmental arteries were occluded, each patient having 7.2 ± 3.1 coiled segmental arteries occluding 64.5% (25-100%) of open segmental arteries within the treated aortic segment. Altogether, 66 anterior radiculomedullary arteries were seen originating between Th8 and L3 levels from 85 (21.9%) segmental arteries. In 10 patients (18.5%), 2 large anterior radiculomedullary arteries were identified, and 1 patient (1.9%) showed 3 anterior radiculomedullary arteries on the spinal arteriography. No spinal cord ischemia or procedure-related complications occurred after minimally invasive segmental artery coil embolization. After 47.9 ± 39.4 days, all patients received endovascular repair of their thoracoabdominal aortic aneurysms. There was no in-hospital mortality. One male patient developed incomplete temporary spinal cord ischemia after endovascular repair. ConclusionsMinimally invasive segmental artery coil embolization of segmental arteries feeding the anterior spinal artery in patients with thoracoabdominal aortic aneurysms to prevent spinal cord ischemia after endovascular repair is feasible and clinically safe.

Intermediate catheter use is associated with complete occlusion and dense packing in coil embolization of unruptured cerebral aneurysms: a propensity score matched study

BackgroundAn intermediate catheter (IMC) can improve the maneuverability and stability of the microcatheter.ObjectiveTo investigate the efficacy and safety of using an IMC in triaxial systems for coil embolization of unruptured...

Determination of Significant Three-Dimensional Hemodynamic Features for Postembolization Recanalization in Cerebral Aneurysms Through Explainable Artificial Intelligence

BackgroundRecanalization poses challenge in coil embolization for cerebral aneurysms. Establishing predictive models for post-embolization recanalization is important for clinical decision-making. However, conventional statistical and machine learning (ML) models may overlook critical parameters during the initial selection process. MethodsIn this study, we automated the identification of significant hemodynamic parameters using a PointNet-based deep neural network (DNN), leveraging their inherent three-dimensional (3D) features. Further feature analysis was conducted utilizing saliency mapping, an explainable artificial intelligence (XAI) technique. The study encompassed the analysis of velocity, pressure, and wall shear stress (WSS) in both pre- and post-coiling models derived from computational fluid dynamic (CFD) simulations for 58 aneurysms. ResultsVelocity was identified as the most pivotal parameter, supported by the lowest P-value from statistical analysis and the highest area under the receiver-operating characteristic curves (AUROC)/precision-recall curves (AUPRC) values from DNN model. Moreover, visual XAI analysis revealed robust injection flow zones with notable impingement points in pre-coiling models, as well as pronounced interplay between flow dynamics and the coiling plane were important 3D features in identifying the recanalized aneurysms. ConclusionsThe combination of DNN and XAI was found to be an accurate and explainable approach not only at predicting post-embolization recanalization but also at discovering unknown features in the future.

Risk factors and management of intraprocedural rupture during coil embolization of unruptured intracranial aneurysms: role of balloon guiding catheter.

Intraprocedural rupture (IPR) is a serious complication of endovascular coil embolization of unruptured intracranial aneurysms (UIAs). Although outcomes after IPR are poor, methods to prevent subsequent neurological deterioration have not yet been investigated. We evaluated the risk factors and management strategies for IPR, particularly the role of balloon guiding catheters (BGCs) in rapid hemostasis. We retrospectively reviewed all UIA cases treated with coil embolization at three institutions between 2003 and 2021, focusing on preoperative radiological data, operative details, and outcomes. In total, 2,172 aneurysms were treated in 2026 patients. Of these, 19 aneurysms in 19 patients (0.8%) ruptured during the procedure. Multivariate analysis revealed that aneurysms with a bleb (OR: 3.03, 95% CI: 1.21 to 7.57, p = 0.017), small neck size (OR: 0.56, 95% CI: 0.37 to 0.85, p = 0.007), and aneurysms in the posterior communicating artery (PcomA) (OR: 4.92, 95% CI: 1.19 to 20.18, p = 0.027) and anterior communicating artery (AcomA) (OR: 12.08, 95% CI: 2.99 to 48.79, p < 0.001) compared with the internal carotid artery without PcomA were significantly associated with IPR. The incidence of IPR was similar between the non-BGC and BGC groups (0.9% vs. 0.8%, p = 0.822); however, leveraging BGC was significantly associated with lower morbidity and mortality rates after IPR (0% vs. 44%, p = 0.033). The incidence of IPR was relatively low. A bleb, small aneurysm neck, and location on PcomA and AcomA are independent risk factors for IPR. The use of BGC may prevent fatal clinical deterioration and achieve better clinical outcomes in patients with IPR.

Covered stent assisted coil embolization of large Buhler aneurysm in setting of chronic celiac trunk occlusion

BackgroundThe arc of Bühler (AOB) is a residual embryonal anastomosis between the celiac artery (CA) and the superior mesenteric artery (SMA). Although usually asymptomatic, it has clinical relevance when compensatory reverse flow between the SMA and the CA in response to celiac artery obstruction leads to aneurysm formation and bleeding. Endovascular coiling is the mainstay therapy because of the deep AOB retropancreatic location, which hinders open surgery.Case presentationWe herein report a case of a 2.8-cm AOB saccular aneurysm and LAM compression of celiac trunk in a 47-year-old man during rehabilitation following motorcycle trauma and vertebral surgery. The patient was considered unsuitable for surgery. Neither conventional coiling nor bare-metal stent and balloon-assisted techniques for coiling were suitable because of the wide necked saccular shape of AOB aneurysm interposed between the SMA and the floor of celiac trunk. To exclude the aneurysm from direct SMA inflow and permit safe and efficient coiling to rule out retrograde sac perfusion, a 9-mm polytetrafluoroethylene stent graft (Viabahn; Gore, Phoenix, AZ, USA) was positioned in the mesenteric artery, followed by antegrade periprosthetic high-density packed coiling of the aneurysm. The AOB remained excluded from mesenteric perfusion. The patient’s clinical condition and abdominal contrast-enhanced multislice computed tomographic findings were unremarkable at the 9-year follow-up.ConclusionThe 9 year long-term efficacy in our case raises the possibility that perigraft coiling following stent-graft deployment in the SMA may represent a valuable technical option for large Bühler aneurysms that are not amenable to stand-alone coiling.

Vertebral Artery Access Considerations in Coil Embolization of Small Superior Cerebellar Artery Aneurysm

Coiling of small superior cerebellar artery (SCA) aneurysms (sSCAAs) is challenging. We aimed to describe anatomical considerations in the vertebral and basilar artery (VA and BA) morphology for decision-making in coiling of sSCAAs. 11 patients with sSCAAs (<5mm) treated at our institution between April 2015 and Februrary 2022 were included to show our concept of deciding access routes in coiling of sSCAAs. The access route was decided based on VA characteristics, BA curvature, and aneurysm laterality. Adequate aneurysm occlusion on angiography (Raymond-Roy grading scale I and II), good outcome (modified Rankin Score 0-2) at the last follow-up, and adverse outcomes were evaluated. Simple coiling (n=2), a balloon-assisted technique (n=3), and stent-assisted technique (n=6) were selected. At the last follow-up (median 13.0 months), adequate aneurysm occlusion and good outcome were obtained in all and 9 patients (n= 10). Adverse outcomes were not observed. When VA dominance was equal, in the straight BA, the microcatheter-insertion into the ipsilateral VA to the aneurysm was favorable to form a "fulcrum" on the contralateral side and obtain the microcatheter stability. When aneurysm was on the concave aspect of the curved BA, the microcatheter-insertion into ipsilateral VA was favorable. As for the convex aspects aneurysm location, the microcatheter-insertion into the contralateral VA can be favored. Further, we described a the VA origin classification as it relates to ease of access from a transradial approach. Vertebrobasilar morphology may be important in deciding access routes in the coiling of sSCAAs.

A Case of a Perianeurysmal Cyst Following Stent-Assisted Coil Embolization of an Unruptured Vertebral Artery Aneurysm

A Case of a Perianeurysmal Cyst Following Stent-Assisted Coil Embolization of an Unruptured Vertebral Artery Aneurysm

Risk factor analyses of contrast leakage and contrast-induced encephalopathy following coil embolization for unruptured intracranial aneurysm

BackgroundContrast-induced encephalopathy (CIE) following endovascular interventions is a rare but serious complication. This study aimed to investigate the risk factors of contrast leakage (CL) and CIE in patients who underwent...

Three-Dimensional (3D) Microcatheter Shaping Using Touch Screen Devices for Cerebral Aneurysm Coil Embolization

In cerebral aneurysm coil embolization, proper microcatheter shaping is crucial to reduce complications and achieve sufficient embolization. Shaping a microcatheter in 3 dimensions (3D) is often required but can be challenging. We assessed the usefulness of a novel shaping on screen (SOS) method that displays real-size 3D rotational angiography (RA) images on a touch screen device during cerebral aneurysm embolization to facilitate 3D microcatheter shaping. In this study, 18 patients with cerebral aneurysm treated with this technique were included. Real-size 3D-RA images obtained during the embolization procedure were displayed on the touch screen device, which allowed for real-time manipulation. The shape of the microcatheter was adjusted to conform to the curvature of the vessel by swiping the touch screen device and bending the mandrel accordingly. We assessed the clinical and angiographic results, along with the accuracy and stability of the microcatheter. No procedure-related complications were observed. The mean packing density was 41%±12%. In all but 1 case, microcatheters were inserted into the aneurysms without guidewire assistance. After coiling, all microcatheter forms were stable. Three-dimensional (3D) microcatheter shaping using touch screen devices during cerebral aneurysm coil embolization may be simple and safe and can achieve high packing density of aneurysms.

Influence of size ratio on retreatment after coil embolization for unruptured bifurcation aneurysms

BackgroundAneurysm size is considered a risk factor for aneurysm rupture, and even small aneurysms may rupture, especially bifurcation aneurysms (BAs), which are occasionally detected. Therefore, we aimed to investigate the predictors of retreatment after coil embolization for unruptured BAs, with a particular focus on the absolute and relative size of the aneurysm (size ratio [SR]). MethodsTo evaluate the predictors of retreatment, patients were divided into two groups: those with and those without retreatment. Patient characteristics and radiographic assessments were compared between the groups. SR was defined as the ratio of the maximum aneurysm diameter and the average diameter of the parent artery. ResultsOverall, 181 unruptured BAs in 176 patients were investigated. The mean age of the patients was 63.8 ± 9.6 years. The mean aneurysm size and SR were 7.18 ± 2.94 mm and 2.49 ± 1.32, respectively. Further, 12 aneurysms with retreatment (6.6 %) and 169 aneurysms without retreatment were compared. In univariate analysis, SR was significantly higher in the group with retreatment (P = 0.02), but aneurysm size was not significantly different between the groups (P = 0.09). Multivariable analysis revealed that SR > 2.6 was a significant predictor of retreatment (P = 0.03; odds ratio: 10.41; 95 % confidence interval: 2.1–51.73). ConclusionsThis study showed that SR influences retreatment after coil embolization for unruptured BAs. Therefore, if the aneurysm size and parent artery diameter were small, as in cases with a large SR, meticulous follow-up after coil embolization is required to detect recurrence and recanalization.