From Digital Reconstruction to Clinical Outcomes: Efficacy Analysis of 3D Printing Technology for Optimizing Microcatheter Shaping in Aneurysm Embolization

aSAH: Aneurysmal Subarachnoid Hemorrhage

IA: Intracranial Aneurysm

CI: Confidence Interval

SD: Standard Deviation

GOS: Glsgow Outcome Scale

IQR: Interquartile Range

SLA: Stereolithography Appearance

3D-DSA: Three-Dimensional Digital Subtraction Angiography

EVT: Endovascular Therapy

CTA: Computed Tomography Angiography

DICOM: Digital Imaging and Communications in Medicine

MRA: Magnetic Resonance Angiography

ICA: Internal Carotid Artery

OR: Odds Ratio

NA: Not Available

ROC: Receiver Operating Characteristic Curve

AUC: Area Under the Curve

SE: Standard Error

Intracranial Aneurysm (IA) is cerebrovascular disorder characterized by localized dilation or bulging of cerebral arteries due to structural weakness in the vessel wall [1]. Both high and low wall shear stress have been implicated in the formation and rupture of aneurysms [2,3]. The prevalence of intracranial aneurysms is approximately 3–5% in the general population, with an annual rupture rate of about 0.95% [4]. Rupture can lead to subarachnoid hemorrhage due to blood leakage into the space surrounding the brain [5]. Endovascular coil embolization has become the first-line treatment for intracranial aneurysms. However, intraoperative complications such as aneurysm rupture and postoperative recurrence often negatively impact patient outcomes. Aneurysm morphology and the degree of embolization density are critical risk factors for recurrence [6]. 

Microcatheter shaping, a key technical step in the procedure, is often challenging. An optimally shaped microcatheter exhibits good navigability, facilitates precise superselection into the aneurysm sac, and provides stability during coil deployment, all of which are crucial for enhancing procedural efficiency and achieving dense aneurysm packing, while simultaneously accomplishing the dual objectives of reducing operation time and decreasing coil consumption [7-9]. Therefore, selecting an appropriate shaping technique, particularly one that enables individualized and accurate shaping, is of paramount importance. Emerging “digital reconstruction” 3D printing technology plays a pivotal role in achieving precise microcatheter shaping. This study aims to compare three-dimensional (3D) printing-assisted microcatheter shaping with traditional shaping methods, to validate the efficacy of this precision shaping approach in reducing operative time, minimizing radiation exposure to both patients and operators, and ultimately improving clinical outcomes [10].

• Patient Population

Patients were prospectively enrolled in this single-center, prospectively, interference study, whose aneurysms located in the C5–C7 segments of the internal carotid artery (ICA), carrying out in the Department of Neurosurgery at Beijing Tiantan Hospital between June 2023 and May 2025. All patients underwent endovascular coil embolization. Antiplatelet premedication with aspirin (100 mg/day) and clopidogrel (75 mg/day) was initiated two weeks before the procedure [11]. The stipulated inclusion criteria encompassed: (1) patients diagnosed with IA by CT angiography (CTA), magnetic resonance angiography (MRA), or digital subtraction angiography (DSA); (2) adult male or female patients (18–75 years old); (3) maximum aneurysm diameter between 2 mm and 15 mm; (4) IA located in the C5–C7 segments of the ICA [12,13]. Conversely, the set of exclusion criteria encompassed: (1) history of aneurysmal subarachnoid hemorrhage; (2) dissecting or fusiform aneurysms [14]; (3) presence of vascular stenosis or vasospasm; (4) use of treatment modalities other than coil embolization; (5) pre-presence of other neurological diseases. The design and process of patient selection were illustrated explicitly in figure 1.

All individual participants or their legally authorized representatives were provided written informed consent for surgery prior to enrollment. This retrospective study adhered to the ethical standards of the 1964 Declaration of Helsinki and its subsequent amendments, and was approved by the Ethics Committee of Beijing Tiantan Hospital (KY 2021-008-01).

 Figure 1: Flow chart showing inclusion or exclusion of patients.

• Clinical Data Collection

Demographic and clinical data were retrieved from the hospital database, including age, gender, medical history. Imaging index included multiple aneurysms, the size and morphology of aneurysm. The flow impingement angle referred to the angle between the direction of aneurysm growth and the direction of blood flow in the parent artery. Angiographic outcomes were assessed utilizing the Modified Raymond-Roy Classification (MRRC). The main contents of MRRC are as follows: Class I: complete occlusion; Class II: residual neck; Class IIIa: residual aneurysm with contrast filling between the coils; Class IIIb: residual aneurysm with contrast filling along the aneurysm wall [10,14].

• Intervention factor-3D Printing Process

Prior to embolization, all patients received either 3D-DSA or CTA examinations at least 24 hours in advance [2,5]. Using Digital Imaging and Communications in Medicine data, researchers reconstructed 3D models of the target vascular segments. During model preparation, the surface resin underwent a 5-minute draining process before manual removal of support structures. Initial cleaning involved 95% ethanol for surface treatment, followed by ultrasonic cleaning with the same solvent. Subsequently, the models were subjected to ultraviolet light curing for 50 minutes [15]. For drying, two methods were employed: either hot air blowing or natural drying in shaded, well-ventilated conditions. The final processing stage included sealing the models in sterilization packaging with indicator strips and performing low-temperature plasma sterilization. 

• Endovascular Procedure

Two senior neurointerventionalists with >10 years of experience performed all procedures using standardized protocols. In the conventional group, microcatheter shaping was achieved through manual mandrel bending techniques guided by 3D-DSA reconstructions. The 3D-printed model group employed patient-specific biomodels for individualized shaping, where microcatheters were precisely conformed to the replica vasculature through thermoplastic deformation. Following femoral access establishment and roadmap-guided navigation, pre-shaped microcatheters were inserted into the aneurysm without microguidewire assistance.

In the 3D-assisted approach, surgeons first inserted the microcatheter tip into the model's predefined aneurysm cavity while carefully aligning the catheter body along its vascular groove. They then applied controlled external force to mold the catheter against the model's inner surface before fixing the shape with steam treatment for 1-2 minutes. After removing the shaped catheter, they advanced it through the guiding catheter into the actual aneurysm to assess proper fit. For conventional shaping, neurointerventionalists manually formed the microcatheters using shaping mandrels according to 3D-DSA findings, subsequently inserting them directly into the aneurysm sac for evaluation [16]. 

• Outcome Definitions

The primary outcome was first-attempt success. It was defined as the number of patients in whom the shaped microcatheter successfully entered the aneurysm sac on the first attempt. Secondary outcomes included operation time, and the number of coils used respectively. The former was defined as the time from the first road-map during superselective catheterization to the first angiographic image after deployment of the final coil. The effectiveness of the shaping technique was evaluated based on three criteria: accessibility, positioning accuracy and stability. Accessibility represented microcatheters could be navigated into the aneurysm without microguidewire or less than attempts were done. Positioning accuracy meant the microcatheter tip could reach the long axis of the aneurysm. Stability referred to the microcatheter tip fell out of the aneurysm during coiling. Postoperative prognosis was assessed by follow-up CTA or DSA imaging, as well as Glasgow Outcome Scale (GOS) score [6,17]. 

• Statistical Analysis

The distribution pattern of each continuous variable underwent assessment by visual examination using Q-Q plots or histograms, and numerically through the Shapiro-Wilk test. Continuous variables were presented as mean ± standard deviation (SD), while categorical variables reported as frequency and percentage. Intergroup comparisons were performed using Chi-square test or Fisher's exact test (for categorical variables), Student's t-test (for normally distributed continuous variables), and the Mann-Whitney U test (for non-normally distributed variables). 

Multivariable regression analysis was subsequently employed to predict outcomes. Considering the factors that may affect surgical time in baseline information, especially imaging factors, five covariates including age and multiple aneurysms were added to the regression model for correction. Then we further selected the corresponding regression method based on the variable type of the outcome. The discriminative ability of the model was evaluated using receiver operating characteristic curve (ROC) analysis, with establishing the area under the curve (AUC) as an indicator of factor's predictive potential. Additionally, subgroup analyses were executed to explore the predictive efficacy of shaping type in subpopulations exhibiting distinct characteristics from the overall cohort.

All analyses were conducted using SPSS Statistics version 26.0 (IBM Corp., Armonk, NY, USA). P value < 0.05 was considered statistically significant.

• Baseline characteristics

A total of 65 unruptured intracranial aneurysms located in the C5–C7 segment of ICA were treated using endovascular therapy. Among these, 30 patients underwent 3D printing-assisted precision microcatheter shaping as intervention group, while the remaining 35 patients received conventional shaping as control group. Patient characteristics were summarized in table 1. Baseline balanced between two groups. There were no statistically significant differences in baseline characteristics between two groups, including demographics, imaging index (p > 0.05). Angiographic outcomes were comparable between groups (p = 0.848). All patients in both groups were discharged in good condition (GOS score of 4 or 5). 

Table 1: Baseline characteristics of patients included.

SD, standard deviation; GOS, Glsgow Outcome Scale;IQR, interquartile range

^aUnit of measurement: mm

• Effectiveness evaluation of 3D shaped microcatheters 

3D technology has demonstrated good effectiveness in terms of microcatheter accessibility (76.67%), positioning accuracy (70.00%), and stability (86.67%) (Table 2). Among the 30 patients in the 3D group, only 4 required re-shaping of the microcatheter outside the body. Postoperative angiography showed that 83.33% of patients in the 3D group achieved complete occlusion. 

Table 2: Evaluation of the 3D shaping microcatheters.

In multivariate regression analysis, the outcomes revealed that use of 3D shaping was not significantly associated with the first-attempt success (OR (95CI%): 2.17 (0.55-8.60), p = 0.269) (Table 3). Nevertheless, in our study, the first-attempt success rate of microcatheters did increase among the population leveraging 3D technology (intervention group vs. control group: 26 (87%) vs. 26 (74%)). Compared with conventional shaping group, operation time was significantly shortened in the 3D shaping group (β (se): -16.03 (5.48), p = 0.005) (Table 3). Meanwhile, 3D shaping significantly reduced the number of coils used in embolization (β (se): -0.82 (0.40), p = 0.046) (Table 3).

Table 3: Multivariable analysis of the relationship between shaping type and outcomes.

OR: Odds Ration; CI: Confidence Interval; SE: Standard Error

• Predictive efficacy estimation

We further evaluated the predictive efficacy of shaping type for operation time given the importance of surgical efficiency in embolization. Since the outcome of operation time was continuous variable, we evaluated the predictive efficacy of it on shaping type, namely conversely operation time as predictive factor. The research employed the ROC curve to ascertain the optimal threshold value for surgery time, which materialized as 88, as determined by the selection of the maximal Youden index. Moreover, AUC accompanied by a 95%CI was shown in figure 2, along with p value corresponding to the independent predictor. The outcomes underscored excellent predictive performance, with an AUC of 0.716 (95%CI: 0.590-0.842).

 Figure 2: ROC analysis for predicting operation time.

• Subgroup analysis 

Due to the potential impact of flow impingement angle on the effect of 3D shaping, we investigated the effect of 3D shaping on different outcomes in populations with different flow impingement angles (Table 4). Analysis based on the flow impingement angle revealed that as the angle between the aneurysm axis and the long axis of parent artery was less than 90°, there was no statistically significant difference in prediction for procedure time (β (se): -15.89 (8.21), p = 0.065), the number of coils used (β (se): -0.92 (0.65), p = 0.166), and first-attempt success rate (OR (95%CI): 1.30 (0.07-25.72), p = 0.863). In contrast, as the angle was greater than 90°, the operation time in the 3D group was significantly shorter than that in the control group (β (se): -18.55 (7.98), p = 0.027). No significant results were observed in the association of shaping type and the number of coils (β (se): -0.48 (0.52), p = 0.361) and first-attempt success rate (OR (95%CI): 2.07 (0.35-12.36), p = 0.426).

Table 4: Subgroup analysis of the association between shaping type and outcomes.

SE: Standard Error

Our study evaluated the efficacy of 3D technology-assisted microcatheter shaping, employing multivariate logistic regression to control for confounding variables in the sample. The analysis demonstrated statistically significant associations between the novel shaping technique and both reduced operation time and decreased coil consumption. Subgroup analysis revealed particularly pronounced time reduction in cases with blood flow impingement angle exceeds 90°. 

The common method of microcatheter shaping using a shaping mandrel remains the most commonly employed technique in clinical practice. In this approach, the surgeon manually bends the shaping mandrel based on the reconstructed 3D-DSA images, inserts it into the microcatheter, and then heats the catheter to fix the shape. This process is often challenging and yields suboptimal results. The primary reasons are: (1) the 2D workstation display lacks depth perception, preventing accurate spatial assessment of the three-dimensional structure and position of the parent artery and target aneurysm, incomplete neck filling due to this uncertainty can result in residual aneurysm and increase the risk of recurrence [7,14]; (2) the actual path of the microcatheter through the parent artery is difficult to predict and heavily reliant on the surgeon experience [7,16]. 

In recent years, several new microcatheter shaping methods have been proposed. For instance, some researchers have used solid 3D-printed vascular and aneurysm models to guide shaping of the mandrel, which improves the surgeon intuitive understanding of the vascular anatomy [13]. However, this still involves manual shaping and does not eliminate the inaccuracy or address the issue of shape rebound inherent to the catheter material. 

In contrast, 3D printing-assisted microcatheter shaping effectively addresses these limitations. Because the vascular geometry is reproduced at a 1:1 scale, the catheter’s intravascular pathway can be simulated the morphology outside the blood vessels, allowing the catheter to conform to the vessel path and stabilize within the aneurysm cavity, ultimately enhancing procedural efficiency [18]. 

In current endovascular embolization procedures for intracranial aneurysms, conventional microcatheter shaping remains the mainstream approach. Comparative outcomes suggest that 3D printing-assisted microcatheter shaping demonstrated no significant difference in first-attempt success rates compared to conventional shaping because the research potentially limited by the small sample size. However, the novel technique exhibited distinct advantages in reducing operation time and decreasing coil consumption. 

One crucial observation in this study was the flow impingement angle, defined as the angle between the incoming blood flow direction and the aneurysm’s long axis. When this angle exceeds 90°, shaping becomes especially difficult—requiring the microcatheter tip to be pre-shaped into a configuration with a bend greater than 90°. The greater deviation between the axis of aneurysm and internal carotid artery, the harder it is to estimate the correct shaping angle using a mandrel, which increases the risk of misalignment and failed catheterization. In this study, only 3 of 15 patients in the 3D group with an angle exceeds 90° failed on the first attempt, compared with 6 of 20 in the control group, demonstrating the superiority of the 3D model. 

Moreover, this new shaping method achieved a complete occlusion rate of 83.3%, supporting its feasibility. For aneurysms with a flow angle exceeds 90°, the model design can intentionally exaggerate the tip angle to compensate for the catheter's elastic recoil, helping the tip to enter the aneurysm smoothly and remain stable, thus facilitating denser coil packing. Additionally, more efficient coil deployment with fewer coils can reduce economic burden and lower recurrence risk. 

However, some limitations remain. The sample size of the 3D group was only 30, which is relatively small and limits the strength of the conclusions. Moreover, this study focused on ICA C5–C7 aneurysms, while other intracranial segments were not addressed. From a clinical standpoint, preparing a 3D model requires at least 30 minutes, making it unsuitable for emergency aneurysm treatment [7,16]. Furthermore, aneurysm location warrants further investigation; for example, aneurysms located on the upper wall of an artery are more vulnerable to hemodynamic impact than those on the lower wall [4]. In the future, 3D model design could be refined based on anatomical site.

The 3D printing-assisted microcatheter shaping technique demonstrates significant advantages in reducing operation time and decreasing coil consumption, thereby enhancing overall surgical efficiency. Comparative analysis revealed no statistically significant difference in first-attempt microcatheter placement success rates when compared to common shaping methods.

• Availability of data and materials 

The data that support the findings of this study are available from the corresponding author upon reasonable request.

The authors declare that they have no conflicts of personal, financial, or institutional interest in any of the materials or methods used in this study or the findings specified in this paper.

We thank all the staff and participants for their contribution to this study.

This work was supported by the Noncommunicable Chronic Diseases-National Science and Technology Major Project (No.2023ZD0505106) and the Natural Science Foundation of China project (82101361).

YHS, YTJ, HCQ and YY brought forward an idea. YHS, YTJ contributed to data curation and project administration. ZKZ, YYZ contributed to methodology and investigation. YHS, YTJ contributed to software. YHS contributed to writing original draft, validation, visualization. HCQ, YY contributed to writing review and editing, resources, supervision, and funding acquisition.

This study was approved by the Institutional Review Board of the Beijing Tiantan hospital (KY 2021-008-01). Informed consent was obtained from all individual participants or their authorized representatives included in the study. All the analyses were performed following the Declaration of Helsinki and the local ethics policies. All authors agreed to the publication of this article.

1. Rice-Canetto TE, Ueno A, Whitney E, Reier L, Houston R, et al. (2005) A Review of the Current Literature on Cerebral Aneurysms. Cureus 17: 80223.
2. Deuter D, Haj A, Brawanski A, Krenkel L, Schmidt NO, et al. (2025) Fast simulation of hemodynamics in intracranial aneurysms for clinical use. Acta Neurochir (Wien) 167: 56.
3. Tsuji M, Ishida F, Yasuda R, Miura Y, Sato T, et al. (2025) Comparison of ELAPSS Score and Computational Fluid Dynamics for Predicting Growth of Small Unruptured Cerebral Aneurysms. Neurol Med Chir (Tokyo) 65: 239-246.
4. Wan J, Jiang Y, Xu L, Zhang Q, Xu G, et al. (2025) Exploration of the effect of morphology and location on hemodynamics of small aneurysms: a variable-controlled study based on two cases with tandem aneurysms. Biomed Eng Online 24: 42.
5. Wang JL, Yuan ZG, Qian GL, Bao WQ, Jin GL (2018) 3D printing of intracranial aneurysm based on intracranial digital subtraction angiography and its clinical application. Medicine (Baltimore) 97: 11103.
6. Chae KS, Jeon P, Kim KH, Kim ST, Kim HJ, et al. (2011) Endovascular coil embolization of very small intracranial aneurysms. Neuroradiology 53: 349-357.
7. Ishibashi T, Takao H, Suzuki T, Yuki I, Kaku S, et al. (2016) Tailor-made shaping of microcatheters using three-dimensional printed vessel models for endovascular coil embolization. Comput Biol Med 77: 59-63.
8. Liu C, Wu X, Hu X, Wu L, Guo K, et al. (2023) Navigating complexity: a comprehensive review of microcatheter shaping techniques in endovascular aneurysm embolization. Front Neurol 14: 1245817.
9. Sluzewski M, Rooij WJ, Slob MJ, Bescós JO, Slump CH, et al. (2004) Relation between aneurysm volume, packing, and compaction in 145 cerebral aneurysms treated with coils. Radiology 231: 653-658.
10. Shin I, Seo M, Lee JY, Jang J, Ahn K-J, et al. (2025) Cumulative in-hospital radiation dose in patients with acute ruptured intracranial aneurysm: a comparative analysis evaluating the effect of radiation dose reducing efforts. J Neurointerv Surg.
11. Shigematsu H, Sunaga A, Yonemochi T, Hirayama A, Sorimachi T, et al. (2024) First Experience with Endovascular Treatment of Cerebral Aneurysms Using Sub-Marker Catheter. J Neuroendovasc Ther 18: 293-297.
12. Kono K, Shintani A, Okada H, Terada T (2013) Preoperative simulations of endovascular treatment for a cerebral aneurysm using a patient-specific vascular silicone model. Neurol Med Chir (Tokyo) 53: 347-351.
13. Imaoka E, Nishihori M, Izumi T, Goto S, Araki Y, et al. (2024) Three-dimensional spiral-shaping method of microcatheter for paraclinoid aneurysms: assessment using silicone models. Nagoya J Med Sci 86: 655-664.
14. Namba K, Higaki A, Kaneko N, Mashiko T, Nemoto S, et al. (2015) Microcatheter Shaping for Intracranial Aneurysm Coiling Using the 3-Dimensional Printing Rapid Prototyping Technology: Preliminary Result in the First 10 Consecutive Cases. World Neurosurg 84: 178-186.
15. Yalman A, Jafari A, Léger É, Mastroianni MA, Teimouri K, et al. (2025) Design, manufacturing, and multi-modal imaging of stereolithography 3D printed flexible intracranial aneurysm phantoms. Med Phys 52: 742-749.
16. Song X, Qiu H, Tu W, Wang S, Cao Y, et al. (2022) Three-dimensional printing-assisted precision microcatheter shaping in intracranial aneurysm coiling. Neurosurg Rev 45: 1773-1782.
17. Ahn JM, Oh JS, Yoon SM, Shim JH, Oh HJ, et al. (2017) Procedure-related Complications during Endovascular Treatment of Intracranial Saccular Aneurysms. J Cerebrovasc Endovasc Neurosurg 19: 162-170.
18. Nakajima S, Sakamoto M, Yoshioka H, Uno T, Kurosaki M (2021) A New Method of Microcatheter Heat-Forming for Cerebral Aneurysmal Coiling Using Stereolithography Three-Dimensional Printed Hollow Vessel Models. Yonago Acta Med 64: 113-119.