Comparison of Flow Diversion and Coiling for the Treatment of Unruptured Intracranial Aneurysms

Computational flow dynamics of a novel next-generation flow diverter

BACKGROUND

Flow-diverting stents (FDS) have revolutionized the treatment of large, giant, and wide-neck intracranial aneurysms. FDS promote thrombosis and aneurysm occlusion by redirecting blood flow within the parent artery. This method of endovascular therapy has proven efficacious, although leaving room for improvement. This study evaluated computational flow dynamics (CFD) and technical feasibility of the novel Surpass Elite FDS (Elite) in comparison with the Pipeline Embolization Device with Shield Technology (PED-Shield) across seven in vitro aneurysm models.

METHODS

Surpass Elite FDS and PED-Shield were assessed primarily with three CFD metrics to quantify flow diversion: inflow rate reduction, impact zone reduction, and turnover time. Seven patient-specific aneurysm models were utilized. These included one basilar tip, one vertebral artery, two middle cerebral artery, and three internal carotid artery aneurysms. Further evaluation of pore densities and velocity profiles was performed to create a robust comparison summary.

RESULTS

Surpass Elite FDS demonstrated greater reduction in inflow rate and impact zone with improved turnover time in all models. Elite additionally displayed higher pore densities at nearly all proximal (inlet), aneurysm, and distal (outlet) points across the aneurysm models.

CONCLUSIONS

The next-generation Surpass Elite established better CFD metrics in comparison with PED-Shield in all in vitro aneurysm models evaluated here. Further, Elite demonstrated a higher pore density at nearly all aneurysm points assessed in this study, promoting enhanced flow diversion and thrombosis in the aneurysm sac. Considering these findings, Elite has strong potential to improve on the occlusion rates of PED-Shield.

Comparative analysis of safety and efficacy of flow diversion with and without surface modification technology, FRED-X, FRED, PED shield and PED in 386 patients: A single center experience with systematic review and network meta analysis

INTRODUCTION

The FRED-X is a newer generation flow diverting stent (FDS) with surface modification that has demonstrated favorable efficacy in treating intracranial aneurysms. Our study provides an analysis of patients treated using FRED-X compared to FRED, PED Shield and PED.

MATERIALS AND METHODS

This was a retrospective single center study and a systematic review with network meta analysis of patients who underwent flow diversion using FRED-X, FRED, PED Shield or PED. Multivariate logistic regression was used to assess long-term outcomes of interest- angiographic occlusion, in-stent stenosis and functional outcome at 6- and 12-month follow up.

RESULTS

386 patients with 386 aneurysms were included. The average age of the cohort was 56.2 years, and 81 % was female. PED had significantly higher aneurysm occlusion rates compared to FRED-X at 6- and 12-months (OR: 3.03, 95 % CI: 1.36-6.62 and OR: 4.01, 95 % CI: 1.26-12.2), with higher odds of absent in-stent stenosis (OR: 9.03, 95 % CI: 3.63-23.3 and OR: 9.58, 95 % CI: 2.56-33.8) at 6- and 12-months, respectively. Rates of stroke, TIA, ICH and mortality were not significantly different across cohorts. All patients were functionally independent on follow-up. A network meta-analysis revealed no significant difference in occlusion rates among each of the included FDS.

CONCLUSION

Our study revealed comparable 12-month occlusion rates and in-stent stenosis between surface modified devices, FRED-X and PED Shield. In addition, angiographic results were comparable between FRED-X and the first generation FRED, however classic PED demonstrated higher rates of angiographic occlusion with lower in-stent stenosis.

Effects of stent-assisted coiling in comparison with flow diversion on intracranial aneurysms

Objective

The aim of this study was to investigate the efficacy and complications of stent-assisted coiling in comparison with flow diversion for wide-necked intracranial aneurysms.

Methods

Patients with wide-necked intracranial aneurysms who were treated with stent-assisted coiling or flow diversion were respectively, enrolled into the stent-assisted coiling or flow diversion treatment group. The clinical and angiographic data were analyzed.

Results

A total of 61 patients with intracranial aneurysms underwent stent-assisted coiling, including 35 (57.4%) female and 26 (42.6%) male patients with 21 (34.4%) ruptured and 40 (65.6%) unruptured aneurysms. Also, 53 patients underwent deployment of flow-diverting devices, including 30 (56.6%) female and 23 (43.4%) male patients with 25 (47.2%) ruptured and 28 (52.8%) unruptured aneurysms. Stent-assisted coiling was performed successfully in 60 patients with 63 stents deployed, and immediate aneurysm occlusion was complete occlusion in 38 (62.3%) aneurysms, residual neck in 12 (19.7%), and residual aneurysm in 10 (16.4%). Procedure-related complications included in-stent thrombosis in three (4.9%) patients, coil protrusion in three (4.9%), and re-rupture of one (1.6%) aneurysm, with a total complication rate of 11.5%. In the flow diversion group, a pipeline embolization device alone was deployed in each of the 24 (45.3%) patients, adjunctive coiling combined with a pipeline device in 29 (54.7%), and double pipeline devices in each of the 6 (11.3%) patients. Immediately after treatment, complete occlusion was achieved in 3 (5.7%) patients with adjunctive coiling, residual neck in 3 (5.7%), and residual aneurysm in 47 (88.7%). Procedure-related complications included aneurysm rebleeding in one patient (1.9%). Clinical and angiographic follow-up was performed 13–49 months (median 29) after the procedure for 49 (80.3%) patients with stent-assisted coiling, with complete aneurysm occlusion in 27 (55.1%) aneurysms, residual neck in 3 (6.1%), residual aneurysm in 5 (10.2%), and recurrence in 14 (28.6%). Follow-up was performed for 14–37 (median 25) months in 45 (84.9%) patients with flow diversion treatment, with complete occlusion in 39 (86.7%) patients, residual neck in 5 (11.1%), residual aneurysm in 1 (2.2%), and no aneurysm recurrence.

Conclusions

Stent-assisted coiling comes with more complications but fewer permanent aneurysm occlusions than flow diverters, and flow diverters are superior to stent-assisted coiling in the treatment of wide-necked intracranial aneurysms, especially in the long-term effect.

Effects of the flow diversion technique on nucleotide levels in intra-cranial aneurysms: A feasibility study providing new research perspectives

Introduction

The flow diverter stent (FDS) has become a first-line treatment for numerous intra-cranial aneurysms (IAs) by promoting aneurysm thrombosis. However, the biological phenomena underlying its efficacy remain unknown. We proposed a method to collect in situ blood samples to explore the flow diversion effect within the aneurysm sac. In this feasibility study, we assessed the plasma levels of nucleotides within the aneurysm sac before and after flow diversion treatment.

Materials and methods

In total, 14 patients with unruptured IAs who were selected for FDS implantation were prospectively recruited from February 2015 to November 2015. Two catheters dedicated to (1) FDS deployment and (2) the aneurysm sac were used to collect blood samples within the parent artery (P1) and the aneurysm sac before (P2) and after (P3) flow diversion treatment. The plasma levels of adenosine monophosphate (AMP), adenosine diphosphate (ADP), and adenosine triphosphate (ATP) at each collection point were quantified with liquid chromatography and tandem mass spectrometry.

Results

The aneurysms were extradural in nine (64.3%) patients and intra-dural in five (35.7%) patients. They presented an average diameter of 15.5 ± 7.1 mm, height of 15.8 ± 4.6 mm, and volume of 2,549 ± 2,794 ml. In all patients (100%), 16 FDS implantations and 42 in situ blood collections were performed successfully without any complications associated with the procedure. The ATP, ADP, and AMP concentrations within the aneurysm sac were decreased after flow diversion (p = 0.005, p = 0.03, and p = 0.12, respectively). Only the ATP levels within the aneurysm sac after flow diversion were significantly correlated with aneurysm volume (adjusted R² = 0.43; p = 0.01).

Conclusion

In situ blood collection within unruptured IAs during a flow diversion procedure is feasible and safe. Our results suggest that the flow diversion technique is associated with changes in the nucleotide plasma levels within the aneurysm sac.

Vascular Response on a Novel Fibrin-Based Coated Flow Diverter

Purpose

Due to thromboembolic complications and in-stent-stenosis after flow diverter (FD) treatment, the long-term use of dual antiplatelet treatment (DAPT) is mandatory. The tested nano-coating has been shown to reduce material thrombogenicity and promote endothelial cell proliferation in vitro. We compared the biocompatibility of coated (Derivo Heal) and non-coated (Derivo bare) FDs with DAPT in an animal model.

Methods

Derivo® bare (n = 10) and Derivo® Heal (n = 10) FD were implanted in the common carotid arteries (CCAs) of New Zealand white rabbits. One additional FD, alternately a Derivo bare (n = 5) or Derivo Heal (n = 5), was implanted in the abdominal aorta (AA) for assessment of the patency of branch arteries. Histopathological examinations were performed after 28 days. Angiography was performed before and after FD implantation and at follow-up.

Results

Statistical analysis of the included specimens showed complete endothelialization of all FDs with no significant differences in neointima thickness between Derivo® bare and Derivo® Heal (CCA: p = 0.91; AA: p = 0.59). A significantly reduced number of macrophages in the vessel wall of the Derivo Heal was observed for the CCA (p = 0.02), and significantly reduced fibrin and platelet deposition on the surface of the Derivo Heal was observed for the AA. All branch arteries of the stented aorta remained patent.

Conclusion

In this animal model, the novel fibrin-based coated FD showed a similar blood and tissue compatibility as the non-coated FD.

Comparison of Molecular Methods and BRAF Immunohistochemistry (VE1 Clone) for the Detection of BRAF V600E Mutation in Papillary Thyroid Carcinoma: A Meta-Analysis

The evaluation of surgically resected papillary thyroid carcinomas (PTC) by immunohistochemistry (IHC) for BRAF mutation has diagnostic, prognostic and therapeutic implications. The goal of this meta-analysis was to perform a systematic review of studies using the VE1 clone (specific for detection of the BRAF V600E mutation) on formalin-fixed paraffin embedded (FFPE) thyroid surgical resection specimens for primary papillary thyroid carcinoma. The authors' molecular techniques, immunohistochemistry protocols, and scoring methods for VE1 immunostaining were also evaluated. This study included 4079 PTCs representing data from 23 studies. The results extracted from each study were split into two different groups, direct sequencing group or PCR group, based on the molecular "gold standard" method used to compare VE1 IHC staining. In the direct sequencing group, the IHC sensitivity was 100% (95% CI 0.97-1.00) and specificity 84% (95% 0.72-0.91). In the PCR group the sensitivity was 98% (95% CI 0.96-0.99) and specificity 89% (95% CI 0.82-0.94). Although immunohistochemical procedures varied by author, the overall performance of the VE1 clone shows that it is highly sensitive and relatively specific for detecting the BRAF V600E mutation in surgical resection specimens. However, standardization of immunohistochemical procedural method and scoring/interpretation criteria may improve the reliability and reproducibility for the use of VE1 clone for future practice.

Experience with FRED junior flow diverter in treatment of cerebral aneurysms at or distal to the circle of Willis

This retrospective study was aimed at assessing our results of endovascular management using the FRED junior flow diverter in cerebral aneurysms at or distal to the circle of Willis. 12 patients with 15 small cerebral vessel aneurysms at or distal to the circle of Willis underwent endovascular treatment using the FRED junior flow diverter at two tertiary care centres in Mumbai, India. 12 of the 15 aneurysms were unruptured, one was treated in an acutely ruptured setting, while two, which had presented with SAH were initially treated with balloon assisted coiling and later treated in a staged manner with a flow diverter. Technical success was 100% in all 15 deployments. Deployments were made across angles ranging from 45° to 180°. There was no stroke/TIA/death in any of the cases, which were unruptured. The O'Kelly-Marotta (OKM) staging was used to analyze angiographic follow up (at least one post procedure angiogram) which was available in 8 patients (10 aneurysms). OKM D & C was seen in 80% of the aneurysms on follow up angiograms. The treatment of small vessel cerebral aneurysms at or distal to the Circle of Willis using a dedicated flow diverter (FRED Jr.) is both technically feasible and highly efficacious.