Coil Embolization Of Cerebral Aneurysms Research Articles

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.

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.

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.

Use of 3D-printing cerebral aneurysm model assisting microcatheter shaping in neurovascular intervention technique training

BackgroundMicrocatheter shaping plays a vital role in coil embolization of cerebral aneurysms, while the complicated method and insufficient training opportunities make it difficult for junior neurovascular clinicians to master this technique. In this program, we constructed a novel training method and assessment system for microcatheter shaping in coil embolization of cerebral aneurysms with 3D technique, and evaluated its efficacy for microcatheter shaping training in junior neurovascular clinicians. MethodsPatient-specific models for cerebral aneurysms in different locations and with different morphologies were selected by experienced senior neurovascular clinicians. The solid polylactic acid model and the soft hollow crystal silicone model of intracranial aneurysms were then made separately for shaping reference and assessment in the training course. Twelve residents without prior experience of microcatheter shaping and 25 neurovascular clinicians who have in vivo experience of microcatheter shaping on 3–5 occasions were selected for this training program and randomly divided into the traditional training group and the experimental training group. Four senior neurovascular clinicians assisted and guided the trainees in two groups and evaluated the time and accuracy of microcatheter shaping. ResultsEighteen trainees were assigned to the traditional training group, among which 4 had prior experience in microcatheter shaping. The other 19 were assigned to the experimental training group, including 8 with prior experience. No statistical difference in the distribution of experienced students between the two groups was noted(P = 0.295). After the training session, the shaping time was found shorter in the experimental training group than that in the traditional training group (40.3.5 ± 16.2 s vs. 54.2 ± 16.4 s, P = 0.014), while the shaping score was found higher in the experimental training group than that in the traditional training group (4.4 ± 0.5 vs. 2.6 ± 1.2, P < 0.001). Specifically, for the trainees without prior experience, the experimental training group also showed less time consumption and higher score (Time: 52.7 ± 7.7 vs. 61.5 ± 9.5, P = 0.02; Score 4.1 ± 0.5 vs. 2.3 ± 1.1, P < 0.01). Meanwhile, for the trainees with prior experience, the advantage was noted in shaping score (4.7 ± 0.3 vs. 3.9 ± 0.6, P < 0.01) but not in time consumption (23.3 ± 4.4 vs. 28.5 ± 3.9, P = 0.07). ConclusionThis training program is quite effective at teaching junior neurovascular physicians the essential surgical abilities required for coiling cerebral aneurysms.

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

BackgroundDespite the great innovations in the neuroendovascular techniques and related materials, there are still notable percentages of recurrent cerebral aneurysms after aneurysm coiling. Aneurysm packing density is well known to affect the initial angiographic result of aneurysm embolization and has a crucial role in the stability of aneurysm obliteration. Although aneurysm coiling is commonly performed under general anesthesia, it could be performed under local anesthesia in certain circumstances.ObjectiveThe purpose of this study is to compare the volume embolization ratio (VER) and angiographic results of cerebral aneurysm embolization performed under local and general anesthesia.Materials and methodsThis is a retrospective cohort analysis of 20 consecutive cases of coiled cerebral aneurysms that were coiled under LA. Further, 15 cerebral aneurysm coil embolization cases have been collected from our data as matched control group.ResultsEmbolization was performed under local anesthesia (Group A) in 20 patients (57.1%) and under general anesthesia (Group B) in 15 patients (42.9%). At the end of the procedure, control angiogram revealed complete obliteration in 13 patients (37.1%), while incomplete obliteration was detected in 22 patients (62.9%). The mean VER 27.9 ± 11.8 without a significant difference between both groups of the study as the VER of Group (A) was 26.05 ± 8.4 and that of Group B was 30.44 ± 15.2. Follow-up angiography at 1 year revealed complete obliteration in 17 (48.6%) of the coiled aneurysms, while incomplete obliteration was detected in 18 patients (51.4%).ConclusionsEndovascular coiling of cerebral aneurysms under local anesthesia is a safe and feasible procedure without significant effects on the VER.

Abstract 122: The P2x4 Inhibitor, Paroxetine Dramatically Prevents Not Only Growth Of Unruptured Cerebral Aneurysms But Also Recanalization After Aneurysm Coil Embolization; A Retrospective Clinical Study, Drug For Aneurysm Study

Introduction: We have suggested that inhibition of P2X4 purinoceptor, which is involved in the endothelial flow sensing mechanism, prevents cerebral aneurysm development and growth in an animal model. Therefore, we retrospectively investigated whether a P2X4 inhibitor, paroxetine used as an antidepressant, has an inhibitory effect on the growth of unruptured cerebral aneurysms and the rate of recanalization after coil embolization. Methods: Among the cases registered in the J-ASPECT Study, the Japanese stroke inpatient reimbursement database, from 2010 to 2019, we searched for cases who were taking paroxetine and with registered unruptured cerebral aneurysm or had undergone cerebral aneurysm coil embolization. We then invited medical centers with these cases to participate in the study and enrolled cases that met the selection criteria by referring to the imaging data and patient background of the cases. The inhibitory effect in the paroxetine-treated group was compared with that of the control group in a multivariate analysis after adjustment for age, gender, and known risk factors. Results: There were 708 cases at 226 facilities nationwide that were potentially matched in the criteria. Seventy-four facilities participated, of which 74 cases at 45 facilities met the selection criteria. A total of 700 control cases were enrolled from 14 core participating centers. The rate of growth incidence of aneurysms was 0.0318 for paroxetine-treated cases (n=36) and 0.0960 for control cases (397). The significant factors (regression coefficients) were paroxetine (-2.26), specific sites of occurrence (-1.28), shape irregularity (1.63), age (0.11), female (1.54), hypertension (-0.55), statin (0.87), and family history of stroke (0.71). The significant factors (odds ratios) in recanalization after 1 year of coil embolization were paroxetine (0.21), complete embolization (0.26), ruptured aneurysm (3.95), and size (1.14). Conclusions: This retrospective study suggests that P2X4 inhibitors including paroxetine may be clinically applicable as agents to inhibit the growth of unruptured cerebral aneurysms and recanalization after 1 year of aneurysm coil embolization. The use of reimbursement information may be useful when collecting very rare cases.

Discontinuation of antiplatelet therapy after stent-assisted coil embolization for cerebral aneurysms.

Dual antiplatelet therapy (DAPT) is usually temporarily used after stent-assisted coil embolization (SACE), and is commonly converted to mono antiplatelet therapy (MAPT) for indefinitely. In this study, we aimed to find the possibility of discontinuing MAPT, and to determine the proper period of DAPT use. We used the Standard Sample Cohort DB dataset from the National Health Insurance Sharing Service. Among approximately 1 million people in the dataset, SACE was performed in 214 patients whose data this study analyzed. The relationship between discontinuation of antiplatelet therapy and intracranial hemorrhage or cerebral infarction was analyzed using multiple logistic regression, considering all confounding variables. The survival rate according to the continuation of antiplatelet therapy was obtained using Kaplan-Meier analysis, and the difference in survival rate according to the continuation of antiplatelet therapy was verified using the log-rank test. The hazard ratio according to continuation of antiplatelet therapy was obtained using the Cox proportional hazards model. The analysis was conducted by applying the same statistical method to the duration of DAPT use. Among 214 patients who underwent SACE, 50, 159 and five patients continued, discontinued and did not use antiplatelet therapy (except at the time of procedure), respectively. In multiple logistic regression analysis, discontinuation of antiplatelet agents (including aspirin) and the period of DAPT use did not affect the occurrence of intracranial hemorrhage or cerebral infarction, considering various confounding factors. In the survival analysis according to the continuation of antiplatelet agents, patients who continued to use antiplatelet agents had a higher survival rate than those in other groups (p=0.00). The survival rate was higher in the rest of the group than in the group that received DAPT for three months (p=0.00). Continuation of antiplatelet agents or the period of DAPT use did not affect the occurrence of intracranial hemorrhage or cerebral infarction. Considering the survival rate, it would be better to maintain at least three months of antiplatelet therapy and it might be recommended to continue DAPT use for 12 months.

Usefulness of PETRA-MRA for Postoperative Follow-Up of Stent-Assisted Coil Embolization of Cerebral Aneurysms.

Image evaluation after stent-assisted coil embolization (SAC) for a cerebral aneurysm is difficult with conventional MRA or CTA because of metal artifacts. Pointwise encoding time reduction with radial acquisition (PETRA)-MRA is a noninvasive imaging examination that can reduce metal artifacts. This study aimed to examine whether PETRA-MRA can be used as a follow-up imaging after SAC. Twelve patients (eight women and four men; mean age, 66.9 ± 13.2 years) underwent SAC for unruptured aneurysms and were retrospectively evaluated using time-of-flight (TOF)- and PETRA-MRA data from the same follow-up session. Two neurosurgeons independently compared the aneurysm occlusion status and flow visualization score in the stented parent artery (4-point scale, where 4 points represented excellent visualization) between TOF- and PETRA-MRA images. If DSA was performed within 3 months before or after PETRA-MRA, the aneurysm assessment was compared between MRA and DSA. The interobserver agreement for each MRA was evaluated. Nine of the 12 patients underwent DSA within 3 months before and after TOF- and PETRA-MRA. The aneurysm occlusion status on DSA was more consistent with PETRA-MRA (eight of nine cases) than with TOF-MRA (one of nine cases; P = 0.023). The median visualization score of the stented parent artery was significantly higher for PETRA-MRA (4 [interquartile range {IQR} 3-4]) than for TOF-MRA (1 [IQR 1-1], P = 0.003). The interobserver agreement for evaluation of the aneurysm occlusion status and visualization score of the parent artery for PETRA-MRA were excellent (κ = 0.98 and 0.93, respectively). In one case, PETRA-MRA was able to detect aneurysm recurrence, leading to subsequent retreatment. PETRA-MRA is a noninvasive examination that can be used to evaluate the occlusion status of aneurysms after SAC and visualize the stented parent artery. PETRA-MRA is useful for repeated follow-up examinations after SAC.

A Case Report of Oculomotor Palsy Associated with Stent-Assisted Coil Embolization of Cerebral Aneurysm

Posterior communicating artery aneurysms (PcomAAs) are the second most common type of aneurysm. Large cerebral aneurysms show various neurological symptoms, especially oculomotor nerve palsy (ONP), due to PcomAAs. Recent research has shown that stent-assisted coil embolization has many side effects. We report the effectiveness of Korean medicine in the treatment of ONP due to PcomAAs after stent-assisted coil embolization. A patient with ptosis and limitation of eye movement was treated with Korean medicine, including herbal medicine (Samlyeongbaegchul-san-byeonbang [參苓白朮散變方] and Uwhangchungsim-won [牛黃淸心元]), acupuncture, electroacupuncture, cupping, and moxibustion. Clinical symptoms were observed by images of the inter-palpebral fissure and eyeball movement. After the treatment, the inter-palpebral fissure and eyeball movement were noticeably improved. These findings suggest that treatment with Korean medicine can be an effective option for the treatment of ONP due to PcomAAs after stent-assisted coil embolization.

Evaluation of Radiation Dose according to Aneurysm Size and Location during Cerebral Aneurysm Coil Embolization

Evaluation of Radiation Dose according to Aneurysm Size and Location during Cerebral Aneurysm Coil Embolization

Global outflow angle influences silent ischemic events in coil embolization for unruptured distal anterior cerebral artery aneurysms.

Distal anterior cerebral artery (DACA) aneurysms are rare, and endovascular treatment of these aneurysms is challenging. Thromboembolic events, including silent ischemic events, are one of the most important complications of coil embolization for cerebral aneurysms. The treatment outcomes and predictors of silent ischemic events in coil embolization for unruptured DACA aneurysms were investigated, focusing on the morphological characteristics of aneurysms, especially the inflow angle (IA) and global outflow angle (GOA). A total of 12 patients with 12 unruptured DACA aneurysms, treated with coil embolization at our institute, were retrospectively investigated. Predictors for silent ischemic events were evaluated by comparing diffusion-weighted imaging (DWI)-positive and DWI-negative patients. Silent ischemic events detected on DWI were observed in eight aneurysms (66.7%). Comparison of the morphological characteristics of aneurysms between the two groups showed a significantly smaller GOA in the DWI-positive group than in the DWI-negative group (172.6 ± 17.7° vs. 216.8 ± 16.8°, P < 0.01). A multivariate analysis showed that GOA <195° was a significant predictor of silent ischemic events (P = 0.04; odds ratio: 23.62; 95% confidence interval: 1.11-490.39). A small GOA was a significant predictor of silent ischemic events after coil embolization for unruptured DACA aneurysms. While some patients can be treated safely with minimally invasive coil embolization, it is necessary to consider surgical clipping in patients at high risk of thromboembolic events with coil embolization.

Association of aortic arch calcification on chest X-ray with procedural thromboembolism after coil embolization of cerebral aneurysm

Procedural thromboembolism after coil embolization of a cerebral aneurysm can occur because of fragmented atherosclerotic plaques in the aortic arch. The purpose of this study was to investigate the relationship between aortic arch calcification (AoAC) observed using preoperative chest X-ray and procedural thromboembolisms after coil embolization of cerebral aneurysms. Between January 2019 and December 2020, 66 patients underwent coil embolization for cerebral aneurysms at our hospital. AoAC was assessed based on the presence of calcification using a preoperative chest X-ray. A procedural thromboembolism was defined as a new positive lesion on diffusion-weighted imaging within 7 days post-procedure. A procedural thromboembolism occurred in 34 (51.5%) patients. The thromboembolism was associated with AoAC (calcification [52.9%] vs. no calcification [6.3%], p < 0.001), aneurysm type (aneurysm with incorporated branches [63.9%] vs. sidewall aneurysm [36.7%], p = 0.047), and a longer procedural time (100.2 ± 34.1 min vs. 79.7 ± 24.9 min, p = 0.007). Multivariable logistic regression analysis showed that AoAC (adjusted odds ratio [OR], 23.566; adjusted 95% confidence interval [CI], 3.921–141.654; p = 0.001) and aneurysm type (adjusted OR, 5.501; adjusted 95% CI, 1.455–20.799; p = 0.012) were independent risk factors for procedural thromboembolism. AoAC on preoperative chest X-ray was associated with a significant increase in the procedural thromboembolism rate. Our study suggests that a procedural thromboembolism after coil embolization of cerebral aneurysms might result primarily from fragmented atherosclerotic plaques in the aortic arch. Preoperative chest X-ray could be a useful tool to predict the risk of procedural thromboembolisms.

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

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

Abstract 1122‐000063: Postoperative Recanalization Factors of Coil Embolization for Cerebral Aneurysms with Comparable Volume Embolization Ratio

This meeting abstract was removed due to the OA licensing requirements of this journal. The full abstract is listed here : https://www.svin.org/files/SVIN_2021_Abstracts_for_Web.pdf

Optimal microcatheter shaping method customized for a patient-specific vessel using a three-dimensional printer.

ObjectiveIn coil embolization of cerebral aneurysms, it is very important to guide microcatheters to the appropriate location in the aneurysm and stabilize them during procedures. To do this, microcatheters need to be properly shaped. In this study, we aim to use a computer application program and a three-dimensional (3D) printer to make a patient-specific shaped microcatheter.MethodsWe simplified, skeletalized, and oversized the existing 3D vascular imaging structures and created the central line structure of the blood vessels. These processes were performed using a computer application program developed by our team. The microcatheters were shaped according to the skeletalized data shape, and the catheterization procedures were simulated using the 3D hollow model of the blood vessel region of interest; the number of hollow models was 10. The compatibility of the microcatheters shaped according to the skeletalized data shape was validated if the microcatheter tip was positioned into the aneurysm.ResultsIn all 10 hollow models, the positioning of the microcatheter into the aneurysms was successful following one or two attempts.ConclusionsWhen shaping microcatheters during endovascular coil embolization, it may be useful to use central line structures with some expansions customized for a patient-specific vessel using a computer application program and a 3D printer. In the future, it may be necessary to apply this technique to actual patients.

The Hybrid Neurosurgeon: The Japanese Experience.

In Japan, hybrid neurosurgeons who perform both open surgical clipping as well as endovascular embolization for the treatment of intracranial aneurysms are common. Although many Japanese neurosurgeons can perform surgical clipping of middle cerebral artery aneurysms or internal carotid artery-posterior communicating artery aneurysms and coil embolization of cerebral aneurysms using simple techniques-only a limited number of neurosurgeons are able to perform surgical clipping and endovascular procedures for anterior communicating artery aneurysms, paraclinoid, or posterior circulation aneurysms using both treatment modalities equally and safely. The senior author's personal experience of more than 500 cases each of surgical clipping and endovascular embolization over the past 25years included 110 cases of basilar tip aneurysms and 104 cases of paraclinoid internal carotid artery (ICA) aneurysms. The safety and efficacy of both treatments appears to be the same, while the durability of surgical clipping is superior to that of endovascular embolization. Among the 110 basilar tip aneurysms, 18 patients were treated by surgical clipping and 94 were treated by endovascular embolization. The initial results of endovascular therapy seemed to be better than those of surgical clipping, although the rate of retreatment was higher. Among the 104 cases of paraclinoid ICA aneurysm, 23 patients were treated by surgical clipping and 81 were treated by endovascular embolization. The results of both treatments seemed to be same, while surgical clipping had apparently good long-term durability. Over the past 15years, the frequency of surgical clipping for basilar tip aneurysms has decreased, and the procedure may eventually be abandoned for this type of aneurysm. However, surgical clipping still offers several advantages in the treatment of paraclinoid aneurysms. Hybrid neurosurgeons can make reasonable decisions concerning the choice of treatment for cerebral aneurysms, as they perform both treatments and understand the benefits and drawbacks of each modality.

Tips for Selecting Balloons or Stents for Cerebral Aneurysms: Effective Use of Each Device

We introduce typical use cases and the appropriate use of balloon catheters and neck bridge stents for coil embolization of cerebral aneurysm. There are two types of balloon catheters: single-lumen and double-lumen catheters. They are also classified into compliant and super-compliant balloons by softness. Neck bridge stents are classified into two types: open-cell and closed-cell stents. Balloon- and stent-assisted techniques are both useful for wide-neck aneurysms. The complication rates of these methods are similar but the stent-assisted technique requires long-term administration of antiplatelets after the procedure. Both techniques have the challenge that the microcatheter is fixed during coil embolization. The semi-jailing technique, in which the stent is partially deployed during coil insertion, solves this problem. Open-cell stents seem more suitable for this technique because they fit better to the vessel wall even in the curved part. It is important to understand the characteristics of each device for safe and effective treatments.

What Are the Important Aspects of Catheter Selection and Navigation?

The goal of coil embolization for cerebral aneurysms is to occlude the cerebral aneurysm to prevent rupture while maintaining the patency of the parent artery. The integrity of cerebral aneurysm occlusion is affected by many factors, including cerebral aneurysm morphology, dome-neck size, dome-neck ratio, and the location of the aneurysm and its parent artery. These factors are then considered pre-operatively and the position of each catheter that allows for the most efficient embolization is assumed. To navigate each catheter to the ideal position, it is necessary to know the characteristics(shape, flexibility, size, etc.)of each catheter. In addition, it is necessary to know the procedure and positioning of balloon catheters or stenting catheters if you use adjunctive techniques. This article will provide guidance for beginners who start coil embolization and provide basic knowledge of how to use catheters, their combinations, and basic methods to help the physician performing optimal coil embolization.

Usefulness of Adjunctive Technique with a TACTICS Catheter for Coil Embolization of Cerebral Aneurysms.

We report the usefulness of the adjunctive technique using a 3.4-Fr TACTICS catheter, which is a distal access catheter (DAC) for coil embolization. Patients who underwent coil embolization with an adjunctive technique using a TACTICS catheter between October 2018 and May 2019 were retrospectively analyzed. In all, 64 aneurysms in 51 patients were treated. Among them, 18 aneurysms in 15 patients (4 ruptured aneurysms and 14 unruptured aneurysms) required an adjunctive technique using a TACTICS catheter. The methods of embolization were the double catheter technique (DCT) for five aneurysms, stent-assisted coiling (SAT) for seven, DCT + SAC for one, and balloon-assisted technique (BAT) for five aneurysms. Aneurysms were located in the anterior communicating artery (Acom A) in three cases, distal anterior cerebral artery (dACA) in one, middle cerebral artery (MCA) in five, internal carotid artery (ICA) in six, basilar artery (BA) in one, and vertebral artery (VA) in two cases. It was easy to access distal intracranial vessels using the TACTICS catheter. In all cases, guiding of the microcatheter, coiling, and stent placement were improved. There were no complications associated with using the TACTICS catheter. Compared with conventional DACs, distal intracranial vessels were more easily accessed using the TACTICS catheter. A TACTICS catheter is useful because DCT and SAC require sufficient operability of the microcatheter.

A New Method of Microcatheter Heat-Forming for Cerebral Aneurysmal Coiling Using Stereolithography Three-Dimensional Printed Hollow Vessel Models.

To perform successful coil embolization of cerebral aneurysms, it is crucial to make an appropriately shaped microcatheter tip for an aneurysm and its parent artery. So far, we manually shaped a mandrel by referencing two-dimensional (2D) images of a rotation digital subtraction angiography (DSA) on a computer screen. However, this technique requires a lot of experience, and often involves trial and error. Recently, there have been increasing reports of manual mandrel shaping using a full-scale three-dimensional (3D) model of an aneurysm and its parent artery output by various types of 3D printer. We have further developed this method by producing a hollow model of an aneurysm and its parent artery with a stereolithography 3D printer and inserting a mandrel inside the model to fit and stabilize a microcatheter tip. Based on digital imaging and communications in medicine (DICOM) data obtained by rotational DSA, 3D images of an aneurysm and its parent artery were created and converted into standard triangulated language (STL) data. A hollow model was produced by extruding the STL data outward in the normal direction, and then a hole was made at the tip of the aneurysm using these STL data. We output these STL data to a stereolithography 3D printer. After cleaning and sterilizing the model, the mandrel was inserted in the direction of the parent artery through the hole made in the tip of the aneurysm and pushed in, creating the ideal mandrel shape. Twelve cases (14 aneurysms) were included in this study. A microcatheter tip was shaped by this method for patients who were scheduled to undergo coil embolization for an unruptured aneurysm. In 13 of the 14 aneurysms, the microcatheter was easily guided into the aneurysms in one or two trials, the position of the microcatheter tip in the aneurysm was appropriate, and the stability during coil embolization was high. Our method differs from the conventional one in that a hollow model made of resin is produced with a stereolithography 3D printer and that the mandrel is shaped by inserting it retrogradely into the hollow model. Using our new method, it will be possible to shape the tip of a microcatheter suitable for safe and stable coil embolization without relying on an operator's experience.