Bilgin, Cem

Purpose Large aneurysms have a higher rupture risk, yet no available in vivo animal model consistently produces large aneurysms for testing endovascular therapies. Recent research suggests that adding calcium chloride (CaCl 2 ) to elastase yields larger aneurysms in a surgical rabbit model. We evaluated whether this effect translates to an endovascular approach by comparing aneurysm sizes created using elastase alone versus a CaCl 2 –elastase combination. Methods Aneurysms were created in the right common carotid artery of New Zealand rabbits. One group received 1 mL porcine elastase; the other received elastase plus 0.055 g CaCl 2 (0.5 M). After four weeks, patency was confirmed via digital subtraction angiography. Two blinded co-authors measured the neck, width, and height of the aneurysms. Aneurysm volumes were estimated using AngioCalc.com. Statistical analyses were performed using either the Mann–Whitney U -test or t -test based on data distribution. Results Twenty-nine (29) New Zealand rabbits were included in the study: six in the CaCl 2 and elastase groups, 23 in the elastase-alone group. All induced aneurysms remained patent at follow-up. Mean neck size was significantly larger in the CaCl 2 + elastase group than in the elastase-alone group (4.4 ± 1.1 mm vs 3.5 ± 0.95 mm; respectively, p = 0.02). Differences in width (4.1 ± 0.92 mm vs 3.4 ± 0.36 mm; p = 0.06), height (9.0 ± 1.1 mm vs 9.1 ± 2.1 mm; p = 0.46), and volume (83.5 ± 38.35 mm ³ vs 53.0 ± 16.94 mm³; p = 0.11) were not significant between CaCl 2 + elastase and elastase-alone, respectively. Conclusions CaCl 2 modestly increased neck size but did not significantly enlarge overall aneurysm dimensions. Further studies are needed to assess its utility in endovascular aneurysm models.

Purpose Aneurysmal rupture and subarachnoid hemorrhage (SAH) have an exceptionally high mortality and morbidity burden. The aim of this study was to develop interpretable machine learning models for predicting short-term poor outcomes defined by the National Inpatient Sample Subarachnoid Hemorrhage Outcome Measure (NIS-SOM). Methods The National Inpatient Sample (NIS) database was queried from 2008 to 2018 to identify patients diagnosed with SAH who had undergone endovascular coiling or clipping for intracranial aneurysm. Demographic, comorbidity, risk factor, and hospital characteristic variables were recorded. Variables were preprocessed, and the feature space was reduced to include the most important features. To predict poor outcomes, machine learning models were trained and cross-validated before being evaluated on a separate testing set. Shapley Additive exPlanations of the best performing model was used for general and local model interpretation. Results Among 18,149 admissions (mean age 55 ± 14 years, 68.8% women), 52.9% had a poor outcome. Test-set AUCs ranged 0.74–0.80; a multilayer perceptron performed best (AUC 0.80, precision 0.74, recall 0.82). SHAP ranked the ten most influential variables: age, neurological comorbidity, paralysis, Medicare insurance, smoking status, Elixhauser burden, fluid-electrolyte disorders, weight loss, arrhythmia, and heart failure. Conclusions The modeling predicted nationwide aSAH prognosis with decent accuracy and highlighted clinical, socioeconomic, and system-level drivers of determinants of poor short-term outcome. These results support the potential of explainable ML tools as complementary tools for early risk stratification, guiding resource allocation, and informing prospective multi-center validation and implementation studies.

Cerebrospinal fluid venous fistulas (CSFVF) can lead to spontaneous intracranial hypotension, causing debilitating symptoms in patients. The transvenous embolization technique has been developed to occlude leakage sites via an endovascular approach. However, the spinal venous anatomy remains relatively unfamiliar to many neurointerventionalists. This technical video presents a swine model designed to train physicians in navigating the spinal venous system, performing embolization injections, observing their spread, and testing new embolization systems for treating CSFVF. Although there are slight anatomical differences, the spinal venous system in swine closely resembles that of humans, including its navigability and employing liquid embolic agents. We successfully embolized multilevel spinal vasculature that can potentially drain into a fistula formation, without any complications.

Abstract Background Percutaneous ablation of parathyroid adenomas provides a minimally invasive treatment option for primary hyperparathyroidism. However, the overall performance of this technique remains underexplored. This meta-analysis evaluates the effectiveness and safety of various ablation techniques for parathyroid adenomas. Methods Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, multiple databases, including Ovid MEDLINE and Cochrane, were systematically searched. Studies that provided separate data for radiofrequency (RF), microwave ablation (MWA), and ethanol ablation technique were included. Outcomes of interest were changes in serum calcium, PTH, and phosphorus levels, along with normocalcemia rates at 6 to 12 months after ablation. Safety outcomes included transient hoarseness, permanent hoarseness, severe hemorrhage, major complications, and severe hypocalcemia. Data were pooled using a random-effects model, with pooled prevalence and 95% CIs calculated. Also, the publication bias was assessed with Egger's test for each outcome measure. Results Twenty studies (815 patients) were included. The posttreatment normocalcemia rate at 6 to 12 months was 85.6% (95% CI, 80.48-90.72). Serum PTH and calcium levels significantly decreased, with mean differences of 101.49 pg/mL (95% CI, 73.50-129.48) and 0.39 mmol/L (95% CI, 0.34-.45), respectively. Permanent hoarseness and major complications were rare, with incidences of 0.28% (95% CI, 0.00-1.05) and 0.31% (95% CI, 0.00-1.09). The safety and efficacy outcomes of RF, MWA, and ethanol ablation were comparable. Conclusion Our findings indicate that percutaneous ablation of parathyroid adenomas is safe and effective within the first year of the treatment. Additionally, they suggest that RF, MWA, and ethanol ablation techniques can each be employed depending on patients' needs without particular limitations.

Background The impact of certain comorbidities on mechanical thrombectomy (MT) outcomes remains largely unexplored. Diabetes mellitus (DM) and admission hyperglycemia have been associated with poor clinical outcomes for patients treated with MT. In this study, we sought to investigate the effects of DM and admission hyperglycemia on MT outcomes. Methods Following PRISMA guidelines, a systematic literature search was conducted in Medline, Embase, Scopus, and Web of Science databases. Data regarding successful recanalization (modified Thrombolysis in Cerebral Infarction [mTICI] ≥2b), functional independence (modified Rankin Scale [mRS] 0–2), excellent outcomes (mRS 0–1), symptomatic intracranial hemorrhage (sICH), and mortality were extracted from the included studies. The pooled odds ratios (ORs) and their corresponding 95% confidence intervals (CIs) were calculated using random effects model. Results Twenty-one studies comprising 9708 patients were included. A total of 2311 patients (24%) had a history of DM, and 2026 patients (21%) had admission hyperglycemia. Admission hyperglycemia was associated with significantly lower odds of mTICI ≥2b (OR = 0.7, 95% CI = 0.55–0.89), mRS 0–2 (OR = 0.47, 95% CI = 0.41–0.53), and mRS 0–1 (OR = 0.43, 95% CI = 0.34–0.55) as compared to normoglycemic state. Patients with hyperglycemia had significantly higher rates of sICH (OR = 2.05, 95% CI = 1.66–2.54) and mortality (OR = 1.99, 95% CI = 1.58–2.52) than normoglycemic patients. Diabetes mellitus was associated with significantly high rates of mortality (OR = 1.74, 95% CI = 1.31–2.3) and lower rates of mRS 0–2 (OR = 0.60, 95% CI = 0.48–0.76) in sensitivity analyses. Conclusion Our results indicate that admission blood glucose levels and DM can negatively affect MT outcomes. Further research should focus on optimizing MT outcomes for these patients.

ABSTRACT As the number of cerebral aneurysms treated with flow diverters continues to increase, it is important to understand what factors influence not only thrombus formation within the aneurysm cavity but also fibrin accumulation across the device and its associated disruption and blockage of the inflow stream. Both processes contribute to the eventual occlusion of the aneurysm or its continued patency and incomplete occlusion which may require future re‐treatment. To investigate fibrin accumulation on flow diverters placed across the neck of cerebral aneurysms, a previously developed computational model that couples flow and fibrin dynamics is used in combination with experimental in vitro models of cerebral aneurysms treated with flow diverters. Fibrin accumulation was previously investigated in four glass models of cerebral aneurysms with varying parent artery geometries placed in a flow loop at different flow rates. Corresponding computational models were constructed and compared with the experimental findings. The computational model based on fibrin production stimulated from flow shear stress and subsequent adhesion to device wires was able to reproduce and explain the fibrin accumulation patterns observed in the experimental aneurysms treated with flow diverters. Specifically, these models indicated that increasing vessel curvature, flow rate, and thrombin concentration induced faster fibrin accumulation and associated aneurysm inflow disruption and blockage. The models described and tested in this paper are valuable to understand the detailed mechanisms leading to aneurysm occlusion and healing or incomplete occlusions after treatment with flow diverting devices.

ABSTRACT 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 in vitro 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 in vitro 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.

Abstract Objective Flow diversion (FD) is a relatively new technique for treating large, wide-necked, or fusiform aneurysms. Although FD is a more preferred option than coiling or clipping techniques in neurosurgery and neuroradiology clinics, the blood flow mechanism inside the aneurysm sac is not fully understood after the treatment. Besides, effective metal surface area (EMSA), a property of an FD related to porosity, shows variation at the patient's aneurysm neck by providing more or less blood flow inside an aneurysm sac than planned, causing nonstagnant or stagnant fluid region formation in the sac, respectively. Thus, the change in FD's EMSA can significantly affect the treatment's effectiveness, making even operation unsuccessful when variation in FD's EMSA at the aneurysm neck is overlooked. Materials and Methods In this study, a large aneurysm of a 52-year-old female patient was numerically investigated by virtually placing two commercially available FDs with different EMSA values one by one into the aneurysm-carrying artery. Results While FD stents at the aneurysm site substantially reduced the blood flow into the aneurysm, an FD with a 15.6% EMSA caused blood to flow in the aneurysm sac to have six times more kinetic energy than that of FD with a 29.5% EMSA. Conclusion Although FD's EMSA value demonstrated nearly up to 20% reduction at the patient's aneurysm neck based on a product catalog value, numerical model results revealed that the stagnated region's formation inside the aneurysm sac could be determined within a 9% difference based on digital subtraction angiography reformat image.