Comparison of lattice and pipeline flow diverters for the treatment of distal intracranial aneurysms: an inverse probability of treatment weighting analysis.

BACKGROUND

Distal intracranial aneurysms are relatively rare in clinical practice and are characterized by distal location, smaller parent vessels, and fragile surrounding brain tissue, which are associated with a relatively higher risk of treatment-related complications such as ischemia and rebleeding. Traditional flow diverter stents have a thin tip, delivery wire can cause intraparenchymal hemorrhage or distal vessel perforation, particularly when attempting to navigate through complex, narrow, or fragile arteries. Therefore, the use of flow diverter devices in the treatment of distal intracranial aneurysms remains technically challenging. Flow diverter devices have been widely used for the treatment of wide-neck intracranial aneurysms; however, comparative data between the domestically developed Lattice device (Accu Medical, China) and the Pipeline Embolization Device remain limited. In this study, we compared the efficacy and safety of these two flow diverters in the treatment of unruptured distal intracranial aneurysms, based on scheduled postoperative imaging follow-up using computed tomography angiography (CTA) and digital subtraction angiography (DSA), focusing on aneurysm occlusion, complications, and branch vessel occlusion.

METHODS

This retrospective study included 47 patients with distal intracranial aneurysms treated with flow diverter devices between January 2020 and July 2025, who underwent implantation of either the Lattice or Pipeline stent. All patients underwent imaging follow-up at 6 months postoperatively using either computed tomography angiography (CTA) or digital subtraction angiography (DSA). Inverse probability weighting (IPTW) was performed to balance baseline characteristics between the two groups. Baseline characteristics before and after IPTW are presented in Table 1. After adjusting for age, sex, hypertension, diabetes, preoperative mRS, aneurysm location, aneurysm morphology (saccular vs. fusiform), neck type (wide vs. narrow), maximum aneurysm diameter, neck size, dome-to-neck ratio, the inflow angle of the aneurysm (IFAA), branch vessel diameter, branch vessel origin, and mean parent vessel diameter, propensity scores were calculated for inverse probability of treatment weighting (IPTW). We applied 1/PS as a weight for the Lattice group and 1/(1 - PS) for the Pipeline group. Inverse probability weighting was applied, and logistic regression analysis was performed to identify factors potentially associated with aneurysm occlusion. Aneurysm healing was assessed using the OKM grading scale, with grades 0-2 defined as poor occlusion and grades 3-4 defined as favorable occlusion.

RESULTS

Compared with the Pipeline group, no statistically significant differences were observed in aneurysm occlusion rates or branch vessel occlusion rates in the Lattice group at a median follow-up duration of 179 days (77.8% vs. 75.9%, p = 0.586). Among 18 patients treated with the Lattice device, 14 achieved favorable occlusion on follow-up imaging (14/18, 77.8%), whereas 22 of 29 patients treated with the Pipeline device demonstrated favorable occlusion (22/29, 75.9%). Branch vessel occlusion covered by the stent occurred in 3 patients in the Lattice group (3/18, 16.7%), which was slightly higher than that in the Pipeline group (2/29, 6.9%); however, this difference was not statistically significant (p = 0.317). Logistic regression analysis identified the IFAA as a potential factor associated with delayed or incomplete aneurysm healing. Specifically, for each 1-degree increase in this angle, the odds of aneurysm occlusion decreased by 3.5% (OR = 0.965, 95% CI: 0.933-0.998, p = 0.037). In addition, IPTW-adjusted univariate weighted logistic regression showed that larger aneurysm neck diameter (OR 0.685, 95% CI 0.505-0.929, p = 0.016), presence of branch vessel origin from aneurysms (OR 0.065, 95% CI 0.011-0.364, p = 0.003) were also associated with unfavorable OKM outcomes.

CONCLUSION

After IPTW adjustment, Lattice and Pipeline devices demonstrated comparable efficacy and safety in the treatment of distal cerebral aneurysms. Aneurysm geometric and anatomical factors, including the inflow angle (IFAA), aneurysm neck diameter and branch vessel origin, were independently associated with incomplete or delayed aneurysm occlusion.