Flow Diverter Treatment Research Articles

What can we learn from machine learning studies on flow diverter aneurysm embolization? A systematic review

BackgroundAs the use of flow diverters has expanded in recent years, predicting successful outcomes has become more challenging for certain aneurysms.ObjectiveTo provide neurointerventionalists with an understanding of the available machine...

Stent retriever expansion as a corrective maneuver to optimize inadequately deployed flow diverter stents.

As flow diversion (FD) is becoming increasingly important in the endovascular treatment of intracranial aneurysms, the rate of technical complications is also increasing. Inadequate FD implantation may lead to both ischemic complications and decreased treatment efficacy. The aim of this study was to evaluate the efficacy of off-label stent retriever (SR) use in managing technical complications associated with FD implantation. A retrospective analysis of data from patients who underwent FD treatment at two neuroradiology centers was performed. The objective was to identify cases in which the FD was inadequately deployed and SR expansion was performed as a corrective maneuver. The analysis included anatomic characteristics, technical information, angiographic and clinical outcomes, and complications. A total of 35 corrective maneuvers with SR were performed in 25 FD treatments. The corrective maneuvers in all treatments were successful, and no additional devices or therapies were required. No procedural complications or technical difficulties were documented. With the growing role of FDs in neurointerventional treatment, familiarity with corrective maneuvers after technical complications or inadequate implantation is important. The findings in our selected cohort demonstrated that SR expansion is an effective and safe corrective maneuver for incompletely opened FDs.

Evaluation of Intracranial Fusiform Aneurysm After Flow Diverter Treatment at Photon-Counting CT.

Evaluation of Intracranial Fusiform Aneurysm After Flow Diverter Treatment at Photon-Counting CT.

Modeling Fibrin Accumulation on Flow-Diverting Devices for Intracranial Aneurysms.

The mechanisms leading to aneurysm occlusion after treatment with flow-diverting devices are not fully understood. Flow modification induces thrombus formation within the aneurysm cavity, but fibrin can simultaneously accumulate and cover the device scaffold, leading to further flow modification. However, the interplay and relative importance of these processes are not clearly understood. A computational model of fibrin accumulation and flow modification after flow diversion treatment of cerebral aneurysms has been developed under the guidance of invitro experiments and observations. The model is based on the loose coupling of flow and transport-reaction equations that are solved separately by independent codes. Interaction or reactive terms account for thrombin production from prothrombin stimulated by thrombogenic metallic wires and inhibition by antithrombin as well as fibrin production from fibrinogen stimulated by thrombin and flow shear stress, and fibrin adhesion to device wires and already attached fibrin. The computational model was demonstrated and tested on idealized vessel and aneurysm geometries. The model was able to reproduce the salient features of fibrin accumulation after the deployment of flow-diverting devices in idealized invitro models of cerebral aneurysms. Namely, fibrin production in regions of high shear stress, initial accumulation at the inflow zone, and progressive occlusion of the device and corresponding flow attenuation. The computational model linking flow dynamics to fibrin production, transport, and adhesion can be used to investigate and better understand the effects that lead to fibrin accumulation and the resulting aneurysm inflow reduction and intra-aneurysmal flow modulation.

Delayed Hyperperfusion Syndrome During the Healing Phase After Flow Diverter Treatment of Giant Intracranial Aneurysms.

Delayed Hyperperfusion Syndrome During the Healing Phase After Flow Diverter Treatment of Giant Intracranial Aneurysms.

Off-label in-silico flow diverter performance assessment in posterior communicating artery aneurysms.

The posterior communicating artery (PComA) is among the most common intracranial aneurysm locations, but flow diverter (FD) treatment with the widely used pipeline embolization device (PED) remains an off-label treatment that is not well understood. PComA aneurysm flow diversion is complicated by the presence of fetal posterior circulation (FPC), which has an estimated prevalence of 4-29% and is more common in people of black (11.5%) than white (4.9%) race. We present the FD-PComA in-silico trial (IST) into FD treatment performance in PComA aneurysms. ISTs use computational modeling and simulation in cohorts of virtual patients to evaluate medical device performance. We modeled FD treatment in 118 virtual patients with 59 distinct PComA aneurysm anatomies, using computational fluid dynamics to assess post-treatment outcome. Boundary conditions were prescribed to model the effects of non-fetal and FPC, allowing for comparison between these subgroups. FD-PComA predicted reduced treatment success in FPC patients, with an average aneurysm space and time-averaged velocity reduction of 67.8% for non-fetal patients and 46.5% for fetal patients (P<0.001). Space and time-averaged wall shear stress on the device surface was 29.2 Pa averaged across fetal patients and 23.5 Pa across non-fetal (P<0.05) patients, suggesting FD endothelialization may be hindered in FPC patients. Morphological variables, such as the size and shape of the aneurysm and PComA size, did not affect the treatment outcome. FD-PComA had significantly lower treatment success rates in PComA aneurysm patients with FPC. We suggest that FPC patients should be treated with an alternative to single PED flow diversion.

The Neck-Crossing Technique Using the Low-Profile Distal Access Catheter in Flow Diverter Placement for Dissecting Posterior Cerebral Artery Aneurysm: A Case Report

AbstractWe report a case in which a novel distal access catheter proved successful in the placement of a flow diverter for a challenging distal cerebral artery lesion. We discuss the advantages and pitfalls of this technique and considerations for its use. A 74-year-old female presented with intermittent headaches, and was diagnosed with a dissecting aneurysm at the proximal right posterior cerebral artery with a sharp bleb, measuring 9.8 mm in diameter. Given the complex vascular anatomy, stent-assisted coil embolization was initially considered but deemed high risk for dual catheter for jailing technique with 6-Fr size guiding catheter due to the tortuosity and stenosis of the parent vessel. Therefore, we opted for flow diverter treatment, which presented its challenges during delivery. By employing a low-profile distal access catheter, Phenom Plus (outer diameter: 4.2-Fr. inner diameter: 1.13 mm; Medtronic, Minneapolis, Minnesota, United States), with a minimal ledge between it and the delivery catheter, Phenom 27 (outer diameter: 2.8-Fr, 0.91 mm; Medtronic), we successfully crossed the neck of the aneurysm with Phenom Plus and placed the flow diverter. While acknowledging potential risks, this case demonstrates the value of the neck-crossing technique using a low-profile distal access catheter as an alternative option for treating challenging peripheral artery aneurysms with flow diverters. This technique offers promise in specific situations where conventional methods pose challenges.

Predictive value of the systemic immune-inflammation index for periprocedural complications in flow diverter treatment for patients with intracranial aneurysms.

Flow-diverter devices (FDs) are effective in treating intracranial aneurysms (IAs) but carry substantial periprocedural risks, particularly ischemic complications. This study aimed to determine if elevated Systemic Immune-Inflammation Index (SII) can independently predict these risks and assess the impact of age and dual antiplatelet therapy on this association. We conducted a retrospective analysis of patients treated with FDs between February 2016 and August 2023, using blood samples taken within six days before surgery to calculate SII. Logistic regression and decision tree analyses assessed the link between SII and periprocedural complications, with subgroups exploring influencing factors. Multivariable analysis identified high SII as an independent predictor of periprocedural complications (OR = 5.306, 95% CI: 1.367-18.455; P = 0.009). The decision tree model confirmed SII > 0.437 as a critical threshold. Subgroup analysis showed a pronounced association of SII with periprocedural complications in patients ≥ 65 years (OR = 36.979, 95% CI: 2.103-650.134; P = 0.014) and in those on clopidogrel plus aspirin therapy (OR = 16.921, 95% CI: 2.733-104.746; P = 0.002). An elevated Systemic Immune-Inflammation Index (SII) > 0.437 significantly correlates with increased periprocedural complications (6.5% vs. 1.8%, P = 0.017). Although not statistically significant, higher SII is associated with a greater rate of ischemic events (3.9% vs. 0.9%). Elevated preoperative SII independently predicts periprocedural complications, particularly ischemic events, in patients undergoing FDs treatment for intracranial aneurysms. This association is particularly pronounced in older patients (> 65 years) and those receiving dual therapy with clopidogrel plus aspirin. Trial Registration: ClinicalTrials.gov (NCT06446778). Registered on May 22, 2024.

Risk Factors for In-Stent Stenosis After Flow Diverter Treatment of Intracranial Aneurysms: A Systematic Review and Meta-Analysis of 2350 Patients.

Recent advances in flow diverter (FD) therapy for intracranial aneurysms have highlighted the need to evaluate risk factors for in-stent stenosis (ISS), a potentially serious complication. This meta-analysis aims to identify risk factors associated with an increased risk of ISS after FD treatment. PubMed, Web of Science, Embase, and SCOPUS databases were systematically searched for studies reporting ISS rates and risk factors after FD therapy for intracranial aneurysms. Odds ratios were calculated using random-effects models to assess potential risk factors associated with ISS. Ten studies involving 2350 patients with 2441 aneurysms were included. Younger age (P = .006) and male sex (P = .003) were associated with higher ISS risk. Smoking also increased the risk (P = .02). Aneurysm location in the posterior circulation (P < .00001) and fusiform morphology (P < .00001) were significant risk factors for ISS, as were ruptured aneurysms (P = .05). Hypertension, hyperlipidemia, diabetes, allergies, and alcohol abuse, as well as aneurysm size, neck width, and parent artery diameter, did not affect ISS risk. Procedural factors like balloon angioplasty, multiple FDs, or FD/coil combinations were not significantly associated with ISS. This meta-analysis identified both nonmodifiable (younger age, male sex) and modifiable (smoking) patient factors, as well as high-risk aneurysm characteristics (posterior circulation, fusiform, ruptured), associated with an increased risk of ISS after FD treatment. These findings highlight the importance of tailored monitoring and management approaches for optimizing outcomes in FD therapy.

Clipping, Aneurysmotomy, and Thrombectomy of an Enlarged Thrombosed Giant Posterior Cerebral Artery Aneurysm After Flow Diverter Treatment: 2-Dimensional Operative Video.

Clipping, Aneurysmotomy, and Thrombectomy of an Enlarged Thrombosed Giant Posterior Cerebral Artery Aneurysm After Flow Diverter Treatment: 2-Dimensional Operative Video.

Efficacy of high-resolution vessel wall MRI in the postoperative assessment of intracranial aneurysms following flow diversion treatment.

Certain patients must undergo frequent postoperative digital subtraction angiography (DSA) after flow diversion (FD) therapy. No imaging modality with an efficacy comparable to that of DSA has been established. This study was conducted to determine the efficacy of contrast-enhanced delay alternating with nutation for tailored excitation (DANTE) T1-sampling perfection with application-optimized contrasts by using different flip angle evolution (SPACE), a high-resolution vessel wall magnetic resonance imaging technique for evaluating the occlusion status of intracranial aneurysms after FD treatment, with DSA serving as the reference standard. This retrospective study included 23 patients with 26 aneurysms who had undergone FD treatment between April 2016 and May 2022. Contrast-enhanced DANTE T1-SPACE and DSA were performed as postoperative follow-up imaging studies at 45 time points, both in the same period. The agreement rates for aneurysm occlusion status in the 45 imaging studies were examined. Contrast-enhanced DANTE T1-SPACE had a sensitivity and specificity of 96.3% (26/27) and 83.3% (15/18), respectively, for detecting aneurysm remnants. Overall, 91.1% (41/45) of findings detected on contrast-enhanced DANTE T1-SPACE were consistent with those on DSA. The findings detected on contrast-enhanced DANTE T1-SPACE were completely consistent with those of intraaneurysmal residual blood flow identified on DSA or high-resolution cone-beam computed tomography images in 74.1% (20/27) of the examinations that showed incomplete occlusion on DSA. Furthermore, parent artery status after FD treatment on contrast-enhanced DANTE T1-SPACE was consistent with that observed on DSA in 97.8% (44/45) of examinations. Contrast-enhanced DANTE T1-SPACE is a very useful option in the follow-up of aneurysms after FD treatment.

Pipeline versus non-pipeline flow diverter treatment for M1 aneurysms: A systematic review and meta-analysis.

The flow diversion treatment of aneurysms located distal to the Circle of Willis has recently increased in frequency. We conducted a systematic review and meta-analysis of the clinical and radiological outcomes of flow diverter (FD) embolization in treating M1 aneurysms. PubMed, Web of Science, Ovid Medline, Ovid Embase, and Scopus were searched up to May 2024 using the Nested Knowledge platform. We included studies assessing the long-term clinical and radiological outcomes for M1 aneurysms. Results of FDs classified as Pipeline Embolization Devices (PED) versus other types of FDs. Angiographic occlusion rates, ischemic and hemorrhagic complications, and favorable clinic outcomes were included. All data were analyzed using R software version 4.2.2. Thirteen studies with 112 total patients (58 patients for PED and 54 patients for other FD devices) were included in our meta-analysis. The overall adequate (complete + near-complete) occlusion rates were 85.1%. The complete occlusion rate was higher with PED than with other FD devices (72.9% PED and 41.6% for non-PED FDs, respectively, p-value <.01). The ischemic complications were 9.9% and 9.0% for the PED and non-PED groups, respectively (p-value = .89). The overall modified Rankin Scale 0-2 was 100% for the non-PED and 97.1% for the PED group (p-value = .51). In-stent stenosis rate was 7.5% for PED devices compared to 2.6% in the non-PED group (p-value = .35). This relatively small meta-analysis showed high rates of adequate and complete occlusion in FD treatment of M1 segment aneurysms, with favorable safety profiles. PEDs were associated with higher rates of complete aneurysm occlusion compared to other types of FDs.

Stent-to-vessel diameter ratio is associated with in-stent stenosis after flow-diversion treatment of intracranial aneurysms

Background and purposeFlow-diversion treatment for intracranial aneurysms has been associated with the development of in-stent stenosis (ISS) for unclear reasons. We assess whether the size of the stent relative to that of the vessel (the stent-to-vessel diameter ratio, or SVR) may be predictive of the development of ISS after treatment with flow diverters. MethodsWe retrospectively reviewed patients with unruptured intracranial aneurysms who underwent flow-diversion treatment using either the Pipeline or Tubridge embolization device from September 2018 to September 2022. The relationship between SVR and ISS was analyzed. Multiple logistic regression models were used to determine the significant predictors. ResultsA total of 458 patients with 481 aneurysms were included. In a mean angiographic follow-up of 10.73 ± 3.97 months, ISS was detected in 68 cases (14.1 %). After adjusting for candidate variables, a higher distal SVR (DSVR) was associated with an increased risk of ISS (adjusted odds ratio [aOR] = 3.420, 95 % confidence interval [CI] = 1.182 – 9.889, p = 0.023). We conducted a subgroup analysis of the two different flow diverters to assess the effects of their individual characteristics. Our results showed a significant association between the DSVR and the incidence of ISS in both the Pipeline (aOR = 4.033, 95 % CI = 1.156-14.072, p = 0.029) and Tubridge groups (aOR = 11.981, 95 % CI=1.005-142.774, p = 0.049). ConclusionA higher DSVR was associated with an increased risk of ISS. This may help neurointerventionalists select an appropriate stent size when conducting flow-diversion treatment for intracranial aneurysms.

It Is Necessary to Pay Attention to Where the Pcom Originate from the Aneurysm to Treat with FD.

Objective With the expansion of indications of flow diverter (FD) for cerebral aneurysms, FD placement for posterior communicating artery (Pcom) aneurysms has been approved. However, it is controversial whether Pcom aneurysms should be treated with FD or not. In this study, we report the outcome of FD treatment for Pcom aneurysms in Japan. Materials and Methods We retrospectively analyzed 36 patients with 38 aneurysms treated with FD placement for Pcom aneurysms between 2015 and 2021 in our hospital. We divided our cases into complete occlusion (CO) and non-CO groups. And we extracted contributing factors to CO using multivariate analysis. We also compared the complications rate among the three types of FDs. Results CO was obtained in 29 cases (79.3%), and complications were observed in 3 cases (7.9%). Multivariate analysis revealed that the type of Pcom branch from the aneurysmal dome was a significant factor contributing to CO (odds ratio: 0.0052, 95% confidence interval 0.000048-0.584, p = 0.029). In terms of complications, complication rate was significantly higher in the Flow-Redirection Endoluminal Device (FRED) group ( p = 0.0491). Conclusion The outcome for Pcom aneurysms treated by FD was acceptable. When treating, we must pay attention to where Pcom originates. Achieving CO with FD is difficult for aneurysms where the Pcom branches from the dome. Furthermore, when treating Pcom aneurysms with FRED, it is necessary to be careful about thromboembolic complications.

Quantitative evaluation of the effects of flow diverter treatment on aneurysm hemodynamics using time-resolved rotational angiography.

There have been immense advancements in the hardware and software of digital subtraction angiography systems over the last several years. These advancements continue to make progress toward the goals of offering better visualization and reducing radiation exposure. A newer advancement in this arena is presenting three-dimension data over time resulting in four-dimensional-digital subtracted angiography visualization. We have evaluated these protocols related to the evaluation of the treatment of intracranial aneurysms with pipeline flow diversion. Four-dimensional-digital subtracted angiography imaging was acquired on an Artis Q Biplane angiographic system (Siemens Healthcare AG, Forchheim, Germany). A six second four-dimensional-digital subtracted angiography protocol was performed pre and post flow diverter placement. Pre and post reconstructed images were sent through a dedicated prototype research workstation (Syngo X-Workplace; Siemens Healthineers AG) for further flow evaluation. The treatment of an aneurysm with flow diversion led to a filling delay of 0.278 ± 0.422 s inside the aneurysms, whereas distal to the aneurysms the filling of the vessel segment occurred earlier post procedural (negative filling delay of -0.15 ± 0.31 s. The flow ratio inside the aneurysm decreased to 63.6 ± 23% of its pre-treatment value and distal to the aneurysm the flow remained substantially the same (flow ratio: 95.6 ± 0.29%). Data showed a relative filling delay of the aneurysm normalized to the distal vessel of 0.43 ± 0.36 s. The relative flow ratio of the aneurysm in comparison to the distal parent vessel was 72.2 ± 31%. Analysis of a four-dimensional-digital subtracted angiography acquisition allows assessment of the effects of flow diversion treatment on aneurysm hemodynamic parameters and shows a significant decrease in flow inside the aneurysm compared to the parent vessel distal to the aneurysm.

How the elastase-induced rabbit aneurysm heals following flow diverter treatment: a histopathological study.

Fibrin deposition is integral to thrombus formation and wound healing. The role of fibrin deposition and subsequent metabolism following flow diversion for aneurysm treatment remains poorly characterized. This study aimed to evaluate the role of fibrin in early thrombus organization after flow diverter treatment. Thirty-five elastase-induced aneurysms were induced in New Zealand white rabbits and subjected to endoluminal flow diversion treatment. The device-bearing arteries were harvested at 1, 3, and 6 months postimplantation and processed for histopathological examination, including a modified picro-Mallory stain (Carstairs method) to visualize fibrin and platelets, immunohistochemical targeting of smooth muscle actin (SMA), and H&E staining for conventional morphological evaluation. Quantitative analysis of tissue components was carried out using the Orbit Image Analysis software. The samples were also assessed qualitatively to investigate the morphology and location of fibrin and other thrombus components within the intra-aneurysmal thrombi. Statistical analyses were conducted using R software version 4.3.1. Fibrin constituted 27.9% of the thrombus tissue within the aneurysm sac for aneurysms harvested at 1 month, and this rate was significantly lower in the 3-month group (10.2%, p = 0.018). The proportion of blood cells within the sac was also notably higher in the 1-month group compared with other time points. The primary tissue filling the dome at 1 month (14/15, 93%) was an unorganized thrombus primarily composed of fibrin, platelets, and red blood cells. Conversely, aneurysms harvested at 1 month had the lowest collagen level (25.6%). However, collagen became the dominant tissue component within the aneurysm sac, accounting for 71.8% of tissue in the 3-month group (p = 0.007). There were no differences observed among the examined components between the 3-month and 6-month groups. On qualitative analysis, collagen-producing SMA-positive myofibroblasts were located near or in between fibrin molecules. Healed aneurysms exhibited myofibroblasts, collagen, and a well-organized fibrin network on the aneurysm neck. In contrast, unhealed aneurysms displayed a poorly organized fibrin network with scattered myofibroblasts at the neck area. These findings indicate that fibrin plays a foundational role in the gradual occlusion of aneurysms after flow diverter treatment. Endovascular approaches that enhance fibrin accumulation could potentially improve aneurysm occlusion rates. Further research is needed to establish the precise role of fibrin in aneurysm occlusion.

Defining light transmission aggregometry cutoff values for clopidogrel and aspirin resistance in flow diversion treatment of intracranial aneurysms.

Concern about thromboembolic events after flow diversion (FD) warrants dual antiplatelet therapy for 3 to 6 months. Platelet function tests are routinely performed prior to the procedure to detect clopidogrel responsiveness, as resistance is associated with CYP2C19 gene polymorphisms. This study aimed to identify optimal cutoff values in light transmission aggregometry (LTA) for clopidogrel and aspirin as predictive indicators of thromboembolic complications. The authors conducted a retrospective analysis of aneurysms treated with FD between 2013 and 2023 at a single academic institution. Patients with LTA data for adenosine diphosphate (ADP) and arachidonic acid (ARA) were included, excluding those with aborted procedures. Receiver operating characteristic curves were plotted for ADP and ARA assays to determine optimal cutoff values. A total of 442 patients harboring 552 aneurysms treated in 485 procedures were selected for this analysis. Complete and near-complete aneurysm occlusion on the last radiological follow-up was achieved in 81.8% of aneurysms in a median last imaging follow-up of 13.9 months. A good functional outcome (modified Rankin Scale score ≤ 2) was achieved in 96.3% of patients on the last follow-up. Thromboembolic complications occurred in 4.9% of procedures, and intracranial hemorrhagic complications in 1.9%. For the ADP assay, a value ≥ 40% reached a sensitivity of 82.1% and a specificity of 42.9% with a positive likelihood ratio (LR) of 1.50. For the ARA assay, a value ≥ 13.5% reached a sensitivity of 82.1% and a specificity of 45.6% with a positive LR of 1.51. This study analyzed the largest FD-treated cohort in which optimal LTA platelet function thresholds for clopidogrel were evaluated and is the first to assess LTA values for aspirin. The authors found that values ≥ 40% for clopidogrel and ≥ 13.5% for aspirin were optimal for predicting thromboembolic complications after FD in treating aneurysms.

Flow diverters treatment planning of small- and medium-sized intracranial saccular aneurysms on the internal carotid artery via constraint-based virtual deployment.

The internal carotid artery (ICA) is a region with a high incidence for small- and medium-sized saccular aneurysms. However, the treatment relies heavily on the surgeon's experience to achieve optimal outcome. Although the finite element method (FEM) and computational fluid dynamics can predict the postoperative outcomes, due to the computational complexity of traditional methods, there is an urgent need for investigating the fast but versatile approaches related to numerical simulations of flow diverters (FDs) deployment coupled with the hemodynamic analysis to determine the treatment plan. We collected the preoperative and postoperative data from 34 patients (29 females, 5 males; mean age 55.74 ± 9.98 years) who were treated with a single flow diverter for small- to medium-sized intracranial saccular aneurysms on the ICA. The constraint-based virtual deployment (CVD) method is proposed to simulate the FDs expanding outward along the vessel centerline while be constrained by the inner wall of the vessel. The results indicate that there were no significant differences in the reduction rates of wall shear stress and aneurysms neck velocity between the FEM and methods. However, the solution time of CVD was greatly reduced by 98%. In the typical location of small- and medium-sized saccular aneurysms, namely the ICA, our virtual FDs deployment simulation effectively balances the computational accuracy and efficiency. Combined with hemodynamics analysis, our method can accurately represent the blood flow changes within the lesion region to assist surgeons in clinical decision-making.

Demonstration of 1000 fps High-Speed Angiography (HSA) in Pre-Clinical In-vivo Rabbit Aneurysm Models During Flow-Diverter Treatment.

High Speed Angiography (HSA) at 1000 fps is a novel interventional-imaging technique that was previously used to visualize changes in vascular flow details before and after flow-diverter treatment of cerebral aneurysms in in-vitro 3D printed models.1 In this first pre-clinical work, we demonstrate the use of the HSA technique during flow-diverter treatment of in-vivo rabbit aneurysm models. An aneurysm was created in the right common carotid artery of each of two rabbits using previously published elastase aneurysm-creation methods.2 A 5 French catheter was inserted into the femoral artery and moved to the aneurysm location under the guidance of standard-speed 10 fps Flat Panel Detector (FPD) fluoroscopy. Following this, a flow diverter stent was placed in the parent vessel covering the aneurysm neck and diverting the flow away from the aneurysm. HSA was performed before and after placement of the flow diverter using a 1000 fps CdTe photon-counting detector (Aries, Varex). The detector was mounted on a motorized changer and was used with a commercial x-ray c-arm system (Fig. 1). During these procedures Omnipaque iodinated contrast was injected into the aneurysm area using a computer-controlled injector at a steady rate of 50 ml/min or 70 ml/min depending on the rabbit to visualize blood flow detail. The contrast injection and x-ray image acquisition were synchronized manually. The x-ray image acquisition was for a duration of 1 second, from which 300 ms was used for velocity analysis during systole. Detailed differences in flow patterns in the region of interest (ROI) between pre and post flow-diverter deployment were visualized at the high frame rates. The Optical Flow (OF) method for velocity calculation was performed upon the acquired 1000 fps HSA image sequences to provide quantitative evaluation of flow.

Treatment of basilar artery aneurysms with two braided stents: Two centers experience of low-profile visualized intraluminal support stents versus Pipeline flow diverters.

Both low-profile visualized intraluminal support (LVIS)stents and Pipeline flow diverters (FDs) are therapeutic strategies for basilar artery (BA) aneurysms, but they have not been directly compared. A total of 132 consecutive patients with 139 BA aneurysms treated with either LVIS stent or Pipeline FDs were analyzed. Propensity score matching (PSM) was used to control for age, sex, hypertension, aneurysm size, shape, location, and duration of follow-up. The treatment results of these two braided stents were compared. LVIS stent was placed in 88 (63.3%) and Pipeline FDs in 51 (36.7%) procedures. Patients with Pipeline FDs tended to be younger and have less hypertension, whereas aneurysms had larger aneurysm size. After PSM, similar complete or near-complete occlusion rates (76.7% vs 73.3%, p = .766) and favorable functional outcomes (86.7% vs 90.0%, p = 1) were achieved in patients treated with LVIS stents and Pipeline FDs, respectively. Further comparisons were conducted at three different locations (basilar apex/basilar trunk/vertebrobasilar artery junction [VBJ]) separately, and the results showed a higher complete or near-complete aneurysm occlusion rate after Pipeline FD treatment than LVIS treatment (86.7% vs 59.2%, p = .012) only at VBJ, where a particularly high proportion of non-saccular shape (70.9%) and a male preponderance were noted. Both braided stents were effective in the treatment of BA aneurysms, with good occlusion rates and favorable functional outcomes. Pipeline FD achieved a particularly higher aneurysm occlusion rate than LVIS stent at VBJ, where lesions often require reconstruction of the diseased vessel.