RAPID Aneurysm: Artificial intelligence for unruptured cerebral aneurysm detection on CT angiography.

OBJECTIVES: Cerebral aneurysms may result in significant morbidity and mortality. Identification of these aneurysms on CT Angiography (CTA) studies is critical to guide patient treatment. Artificial intelligence platforms to assist with automated aneurysm detection are of high interest. We determined the performance of a semi-automated artificial intelligence software program (RAPID Aneurysm) for the detection of cerebral aneurysms. MATERIALS AND METHODS: RAPID Aneurysm was used to detect retrospectively the presence of cerebral aneurysms in CTA studies performed between January 2019 and December 2020. The gold standard was aneurysm presence and location as determined by the consensus of three expert neuroradiologists. Aneurysm detection accuracy, sensitivity, specificity, positive predictive value, negative predictive value, and positive and negative likelihood ratios by RAPID Aneurysm were determined. RESULTS: 51 patients (mean age, 56±15; 24 women [47.1%]) with a single CTA were included. A total of 60 aneurysms were identified. RAPID Aneurysm had a sensitivity of 0.950 (95% CI: 0.863-0.983), specificity of 1.000 (95% CI: 0.996-1.000), a positive predictive value (PPV) of 1.000 (95% CI: 0.937-1.000), a negative predictive value (NPV) of 0.997 (95% CI: 0.991-0.999), and an accuracy of 0.997 (95% CI: 0.991-0.999) for cerebral aneurysm detection. CONCLUSIONS: RAPID Aneurysm is highly accurate for the detection of cerebral aneurysms on CTA.

Stent-Induced Vascular Remodeling in Two-Step Stent-Assisted Coiling Treatment of Brain Aneurysms: A Closer Look Into the Hemodynamic Changes During the Stent Healing Period.

Stenting has become an important adjunctive tool for assisting coil embolization in complex-shaped intracranial aneurysms. However, as a secondary effect, stent deployment has been related to both immediate and delayed remodeling of the local vasculature. Recent studies have demonstrated that this phenomenon may assume different roles depending on the treatment stage. However, the extent of such event on the intra-aneurysmal hemodynamics is still unclear; especially when performing two-step stent-assisted coiling (SAC). Therefore, we performed computational fluid dynamics (CFD) analysis of the blood flow in four bifurcation aneurysms focusing on the stent healing period found in SAC as a two-step maneuver. Our results show that by changing the local vasculature, the intra-aneurysmal hemodynamics changes considerably. However, even though changes do occur, they were not consistent among the cases. Furthermore, by changing the local vasculature not only the shear levels change but also the shear distribution on the aneurysm surface. Additionally, a geometric analysis alone can mislead the estimation of the novel hemodynamic environment after vascular remodeling, especially in the presence of mixing streams. Therefore, although the novel local vasculature might induce an improved hemodynamic environment, it is also plausible to expect that adverse hemodynamic conditions might occur. This could pose a particularly delicate condition since the aneurysm surface remains completely exposed to the novel hemodynamic environment during the stent healing period. Finally, our study emphasizes that vascular remodeling should be considered when assessing the hemodynamics in aneurysms treated with stents, especially when evaluating the earlier stages of the treatment process.

Non-Newtonian Blood Modeling in Intracranial Aneurysm Hemodynamics: Impact on the Wall Shear Stress and Oscillatory Shear Index Metrics for Ruptured and Unruptured Cases.

When simulating blood flow in intracranial aneurysms (IAs), the Newtonian model seems to be ubiquitous. However, analyzing the results from the few studies on this subject, the doubt remains on whether it is necessary to use non-Newtonian models in computational fluid dynamics (CFD) simulations of cerebral vascular flows. The objective of this study is to investigate whether different rheology models would influence the hemodynamic parameters related to the wall shear stress (WSS) for ruptured and unruptured IA cases, especially because ruptured aneurysms normally have morphological features, such as lobular regions and blebs, that could trigger non-Newtonian phenomena in the blood flow due to low shear rates. Using CFD in an open-source framework, we simulated four ruptured and four unruptured patient-specific aneurysms to assess the influence of the blood modeling on the main hemodynamic variables associated with aneurysm formation, growth, and rupture. Results for WSS and oscillatory shear index (OSI) and their metrics were obtained using Casson and Carreau-Yasuda non-Newtonian models and were compared with those obtained using the Newtonian model. We found that all differences between non-Newtonian and the Newtonian models were consistent among all cases irrespective of their rupture status. We further found that the WSS at peak systole is overestimated by more than 50% by using the non-Newtonian models, but its metrics based on time and surface averaged values are less affected-the maximum relative difference among the cases is 7% for the Casson model. On the other hand, the surface-averaged OSI is underestimated by more than 30% by the non-Newtonian models. These results suggest that it is recommended to investigate different blood rheology models in IAs simulations when specific parameters to characterize the flow are needed, such as peak-systole WSS and OSI.

Ischemic Stroke After Treatment of Intraprocedural Thrombosis During Stent-Assisted Coiling and Flow Diversion.

BACKGROUND AND PURPOSE: Intraprocedural thrombosis poses a formidable challenge during neuroendovascular procedures because the risks of aggressive thromboembolic treatment must be balanced against the risk of postprocedural hemorrhage. The aim of this study was to identify predictors of ischemic stroke after intraprocedural thrombosis after stent-assisted coiling and pipeline embolization device placement. METHODS: A retrospective analysis of intracranial aneurysms treated with stent-assisted coiling or pipeline embolization device placement between 2007 and 2016 at 4 major academic institutions was performed to identify procedures that were complicated by intraprocedural thrombosis. RESULTS: Intraprocedural thrombosis occurred in 34 (4.6%) procedures. Postprocedural ischemic stroke and hemorrhage occurred in 20.6% (7/34) and 11.8% (4/34) of procedures complicated by intraprocedural thrombosis, respectively. Current smoking was an independent predictor of ischemic stroke. There was no statistically significant difference in the rate of ischemic stroke or postprocedural hemorrhage with the use of abciximab compared with the use of eptifibatide in treatment of intraprocedural thrombosis. CONCLUSIONS: Current protocols for treatment of intraprocedural thrombosis associated with placement of intra-arterial devices were effective in preventing ischemic stroke in ≈80% of cases. Current smoking was the only independent predictor of ischemic stroke.

Hemodynamic Characterization of Geometric Cerebral Aneurysm Templates Treated With Embolic Coils.

Embolic coiling is one of the most effective treatments for cerebral aneurysms (CAs), largely due to the hemodynamic modifications that the treatment effects in the aneurysmal environment. However, coiling can have very different hemodynamic outcomes in aneurysms with different geometries. Previous work in the field of biofluid mechanics has demonstrated on a general level that geometry is a driving factor behind aneurysmal hemodynamics. The goal of this study was to relate two specific geometric factors that describe CAs (i.e., dome size (DS) and parent-vessel contact-angle (PV-CA)) and one factor that describes treatment (i.e., coil packing density (PD)) to three clinically relevant hemodynamic responses (i.e., aneurysmal root-mean-square velocity (Vrms), aneurysmal wall shear stress (WSS), and cross-neck flow (CNF)). Idealized models of basilar tip aneurysms were created in both virtual and physical forms to satisfy two-level multifactorial experimental designs. Steady and pulsatile flow hemodynamics were then evaluated in the virtual models using computational fluid dynamics (CFD) (before and after virtual treatment with finite element (FE) embolic coil models), and hemodynamics were also evaluated in the physical models using particle image velocimetry (PIV) (before and after treatment with actual embolic coils). Results showed that among the factors considered, PD made the greatest contributions to effects on hemodynamic responses in and around the aneurysmal sac (i.e., Vrms and WSS), while DS made the greatest contributions to effects on hemodynamics at the neck (i.e., CNF). Results also showed that while a geometric factor (e.g., PV-CA) may play a relatively minor role in dictating hemodynamics in the untreated case, the same factor can play a much greater role after coiling. We consider the significance of these findings in the context of aneurysmal recurrence and rupture, and explore potential roles for the proposed methods in endovascular treatment planning.

Safety of Onyx Transarterial Embolization of Skull Base Dural Arteriovenous Fistulas from Meningeal Branches of the External Carotids also Fed by Meningeal Branches of Internal Carotid or Vertebral Arteries.

PURPOSE: To analyze the angiographic and clinical results of transarterial embolization with Onyx (Medtronic-Covidien, Irvine, CA) in dural arteriovenous fistulas (DAVFs) partially fed by arteries arising from the carotid siphon or the vertebral arteries. METHODS: We isolated 40 DAVFs supplied by either the tentorial artery of the internal carotid artery (ICA) or the posterior meningeal artery of the vertebral artery. These DAVFs were embolized with Onyx through the middle meningeal artery or the occipital artery. We reviewed the occurrence of reflux into the arteries of carotid or vertebral origin. RESULTS: In all the cases, reflux occurred into the first millimeters of the DAVF arterial feeders arising from carotid or vertebral arteries but slowly enough to be controlled by interruption of Onyx injection. Reflux was always minimal and Onyx never reached the ostium of the arteries. No cerebral ischemic complications occurred in our series. CONCLUSION: The behavior of Onyx is clearly different from that of cyanoacrylate glue, resulting in superior control during injection. Reflux into arteries arising from the ICA or vertebral artery during DAVF treatment always carries a risk of unintentional non-target embolization of normal cerebral vasculature but Onyx appears to be safe in this situation.

The Use of Single Stent-Assisted Coiling in Treatment of Bifurcation Aneurysms: A Multicenter Cohort Study With Proposal of a Scoring System to Predict Complete Occlusion.

BACKGROUND: The development of stent-assisted coiling has allowed for the endovascular treatment of wide-necked bifurcation aneurysms. A variety of options exist, and little is known about the optimal stent configuration in this setting. We report a large multicenter experience of stent-assisted coiling of bifurcations aneurysms using a single stent, with attention to factors predisposing to aneurysm recanalization. OBJECTIVE: To assess the safety and efficacy of single stent-assisted coiling, in addition to analyzing the factors associated with recanalization, and proposal of a predictive scoring scale. METHODS: A multicenter retrospective analysis of bifurcation aneurysms treated with a single stent-assisted coiling technique between 2007 and 2015 was performed. Clinical and radiographic data were collected and used to develop a scoring system to predict aneurysm occlusion. RESULTS: A total of 74 bifurcation aneurysms were treated with single stent-assisted coiling. At a median follow-up of 15.2 mo, complete occlusion or remnant neck was achieved in 90.6% of aneurysms. Aneurysm location, maximal diameter, neck size, and alpha angle were predictive of aneurysm occlusion at last follow-up. A scoring system to predict complete occlusion based on these factors was developed. An increasing score correlated with a higher rate of complete occlusion. CONCLUSION: The treatment of bifurcation aneurysm using single stent technique for stent-assisted coiling is safe and effective. Complete occlusion or remnant neck occlusion was achieved in 90.6% of cases. Class III aneurysms can be effectively treated using a single stent, while class I may require Y-stent technique.

Flow Diverters for Treatment of 160 Ophthalmic Segment Aneurysms: Evaluation of Safety and Efficacy in a Multicenter Cohort.

BACKGROUND: Treatment of ophthalmic segment aneurysms (OSA) remains challenging. Flow diverter stents (FDS) have evolved as a promising endovascular treatment option for aneurysms of the internal carotid artery and are associated with high occlusion rates and a favorable morbidity and mortality profile. OBJECTIVE: To determine safety and efficacy of FDS for OSA in a large, multicenter cohort. METHODS: A retrospective analysis of prospectively maintained databases of 127 consecutive patients harboring 160 OSA treated with FDS was performed. Aneurysms were classified based on location and morphology. Follow-up with digital subtraction angiography (DSA) was performed 6 to 18 months after treatment. RESULTS: Follow-up DSA was available for 101 (63.1%) aneurysms with a mean follow-up of 18 months. Complete occlusion was observed in 90 aneurysms (89.1%), near-complete occlusion (>95%) in 3 (3%), and incomplete occlusion (<95%) in 8 aneurysms (7.9%). One aneurysm was retreated with another FDS (0.9%). No risk factors for incomplete occlusion were identified. The OA was occluded at the latest follow-up in 6 cases (7.1%). Permanent morbidity occurred in 4 patients (3.1%), and there was no mortality related to the FDS procedure. CONCLUSION: Treatment of OSA with FDS was found to be safe and effective. The retreatment rate was extremely low and aneurysms that occluded did not reanalyze.

Impact of Coil Packing Density and Coiling Technique on Occlusion Rates for Aneurysms Treated with Stent-Assisted Coil Embolization.

BACKGROUND AND OBJECTIVE: Stent-assisted coil embolization is an established endovascular technique for wide-necked intracranial aneurysms. Although recanalization after coil embolization is reduced with the use of a stent, the impact of aneurysm packing density is less clear in stent-coiled aneurysms. The purpose of the present study was to assess packing density in stent-coiled aneurysms and evaluate its effect on recanalization and retreatment. METHODS: A retrospective analysis of consecutive aneurysms treated with stent-assisted coiling was performed at 2 academic institutions between 2007 and 2015. Aneurysm occlusion was assessed using digital subtraction angiography. Packing density was calculated using the AngioCalc app. RESULTS: Two hundred fifty-three aneurysms were identified (median age, 59 years). The median packing density was 35.3%. At last follow-up, 72.7% of aneurysms were completely obliterated and 19.4% had a neck remnant. Complete occlusion was associated with smaller aneurysms and coiling through stent interstices. A higher packing density was associated with increased rate of complete occlusion when analyzed as continuous variable. After adjustment for confounding variables, packing density was no longer predictive of complete occlusion (odds ratio = 1.018, P = 0.122). Similarly, there was no significant association between aneurysm occlusion, retreatment, and packing density when assessed by categories of high (>22%), moderate (12%-22%), and low (<12%) packing density. CONCLUSIONS: Aneurysm size remains the most important predictor of aneurysm recanalization and retreatment after stent-assisted coiling. Although higher packing densities were associated with increased rates of aneurysm occlusion in unadjusted statistical comparisons, this finding was no longer significant after adjusting for confounders.

Neurovascular reconstruction with flow diverter stents for the treatment of 87 intracranial aneurysms: Clinical results.

BACKGROUND: Flow diverter stents represent a new endovascular tool to treat complex aneurysms, such as giant, large, wide-necked and fusiform. The highly dense mash of these stents reduces inflow and outflow inside the aneurysm, resulting in intra aneurysmal thrombosis and stent endothelialization. OBJECTIVES: To present the results of treatment of intracranial aneurysms with flow diverter stents in a single center. METHODS: Retrospective review of 77 patients with 87 aneurysms treated using two different types of flow diverter stent, the Pipeline Embolization Device and SILK stent, between October 2010 and September 2013 in an interventional neuroradiology center. RESULTS: Flow diverter stent placement was successful in 98% of the lesions and resulted in an immediate major stasis within most of the treated aneurysms. The overall aneurysm occlusion rate at six months and 18 months was 80% and 84% respectively. Symptomatic complications occurred in 11 patients (14.3%) with morbidity in eight (10.4%) and mortality in three patients (3.9%). CONCLUSION: Flow diversion is a promising technique for treatment of challenging intracranial aneurysms with acceptable morbidity. A high rate of complete occlusion for small large necked aneurysms, a low morbidity and mortality rate and no recanalization encourage their use in these aneurysms. Further studies accessing long-term aneurysm occlusion and recanalization are required.

Thoracic aorta dissection associated with aberrant right subclavian artery: treatment with endovascular stent-graft placement.

Dissecting aneurysm is the condition produced by separation of the layers of the arterial wall by circulating blood. Although rare, the coexistence of aortic dissection and aberrant right subclavian artery may be catastrophic. In this study we report the endovascular treatment of a patient with thoracic aorta dissection associated with aberrant right subclavian artery. Aortic clamping proximal to the left subclavian artery in a patient with an aberrant right subclavian artery slows or eliminates flow to both vertebral arteries. Endovascular repair eliminates the complications associated with aortic clamping during surgical repair in the presence of an aberrant right subclavian artery; therefore, it should be considered the treatment of choice in this situation.

Predictors and outcomes of suspected heparin-induced thrombocytopenia in subarachnoid hemorrhage patients.

BACKGROUND: Heparin-induced thrombocytopenia (HIT) is a dreaded complication of heparin-related products and correlates with a worse outcome in aneurysmal subarachnoid hemorrhage (SAH) patients. OBJECTIVE: To study the risk factors and outcomes of SAH patients suspected of having HIT, confirmed as present or absent by the platelet factor 4 (PF4) antibody test. METHODS: All patients with presumed aneurysmal, nontraumatic SAH and having undergone a PF4 test were identified through our research patient database. Charts, laboratory values and images were analyzed retrospectively. RESULTS: We identified 166 patients with SAH who were tested for HIT; 42 patients (25%) had a positive antibody test. There was no difference in platelet profiles or mean platelet nadirs of HIT+ and HIT- patients (147 ± 93 vs. 153 ± 86 ×10(9)/l, respectively). Univariate analysis identified gender, magnesium prophylaxis, Fisher group 3, clipping versus coiling, presence of angiographic vasospasm, number of vasospasm treatments, and day of HIT testing as potential risk factors associated with HIT. A multivariate analysis indicated that female gender (OR 8.2, 95% CI 2.0-33.2), greater number of vasospasm treatments (OR 1.5, 95% CI 1.2-2.0), later day of HIT testing (OR 1.2, 95% CI 1.1-1.3), and clipping (OR 5.0, 95% CI 1.42-10.0) were independently associated with HIT positivity. HIT+ patients showed more infarcts on CT, longer ICU and hospital stays and worse modified Rankin Scale scores on discharge. CONCLUSION: The presence of HIT in SAH has adverse consequences and is more likely in female patients who have undergone aneurysm clipping and require multiple endovascular vasospasm treatments.

Reversible parkinsonism after treatment of dural arteriovenous fistula.

BACKGROUND AND PURPOSE: The most common causes of parkinsonism are degenerative and irreversible. Structural causes of reversible parkinsonism are exceptionally rare, but have been reported in association with deep cerebral venous thrombosis and dural arteriovenous fistula (DAVF). We now report a case of parkinsonian syndrome reversed by treatment of a dural arteriovenous malformation. METHODS: Case report with retrospective review of relevant clinical, imaging, and treatment data. RESULTS: A 79-year-old man presented with complaints of a slowly progressive parkinsonian syndrome and tinnitus. Brain magnetic resonance imaging (MRI) showed numerous serpiginous flow voids highly suggestive of a vascular malformation. Cerebral angiography revealed a Cognard grade IIa + b left transverse sinus DAVF. The patient underwent combined endovascular and surgical treatment in three stages over a week's time, with total obliteration of the DAVF and complete normalization of his symptoms and neurological examination. CONCLUSION: Although rare, DAVF should always be considered as a potential cause of progressive parkinsonism. This diagnosis is of great importance because of its potential reversibility.

Power-pulse thrombolysis and stent recanalization for acute post-liver transplant iliocaval venous thrombosis.

Postoperative inferior vena cava (IVC) thrombosis is a potentially lethal complication in a liver transplant recipient. We report the case of a 57-year-old liver transplant recipient, who developed acute, postoperative, markedly symptomatic complete IVC, ilial-femoral-caval, and left renal vein thrombosis. After treatment with power-pulse tissue plasminogen activator thrombolysis, thrombectomy, and stent placement, the IVC and iliac veins were successfully recanalized. At 2.5-year imaging and laboratory follow-up, the IVC, iliac, and renal veins remained patent and graft function was preserved.

A report of two cases with dolichosegmental intracranial arteries as a new feature of PHACES syndrome.

BACKGROUND: We describe two previously unreported cases with complete or incomplete expression of PHACES syndrome, a rare congenital syndromal pediatric disorder, which is characterized by posterior cranial fossa malformations, large facial hemangiomas, arterial anomalies, coarctation of the aorta and cardiac defects, abnormalities of the eye, sternal and supraabdominal raphe defects. CASE REPORTS: These two children exhibited a feature not reviewed extensively in the literature, namely, segmental elongation and dilatation of intracranial arteries associated with intracranial occlusive arterial disease, predominantly on the anterior division of the internal carotid artery (ICA) and on the P2 segment of the posterior cerebral artery. This dolichoectasia was found at the distal cervical internal carotid artery, the intradural segment of the ICA before the division, the trigeminal artery, and the posterior division of the ICA. We presume that the different forms of arterial involvement in PHACES syndrome (arterial stenoses, segmental agenesis of vessels, and the dolichoectasia described in this study) constitute a spectrum of angiogenetic dysfunctions related to an embryonic event involving several cephalic neural crest segments of the dorsal aorta.

Sinus pericranii: diagnostic and therapeutic considerations in 15 patients.

INTRODUCTION: Sinus pericranii (SP) is a rare, usually asymptomatic condition characterized by a large communication between the intra- and the extracranial venous drainage pathways in which blood may circulate bidirectionally through dilated veins of the skull. We describe our diagnostic and therapeutic experience with SP, with a special focus on the vascular analysis of digital subtraction angiography (DSA). METHODS: DSA images of 15 patients were evaluated with regard to the delay in opacification of the scalp vessels, the absence or distortion of the superficial cortical veins in the vicinity of the SP, the drainage patterns of the superior sagittal sinus, and the degree of maturation of the venous outlets of the brain. SP were classified either as "dominant", if the main stream of contrast flow used the SP to drain the brain bypassing usual venous outlets, or as "accessory", if only a small part of the venous outflow occurred through the extradiploic vessels. RESULTS: All patients presented with a nonpulsatile, soft-tissue mass. The lesion was on the midline in 14 of 15 patients, frontal in 12 patients, and parietal in 2 patients. In 13 patients, associated intracranial venous anomalies were present, eight of which were developmental venous anomalies. Seven patients had a dominant SP, and eight an accessory SP. CONCLUSION: SP can be considered the cutaneous sign of an underlying venous anomaly. If treatment is contemplated, analysis of the drainage pattern of the SP has to be performed. Treatment should be avoided in dominant SP or if its accessory role constitutes the only collateral pathway of an underlying venous anomaly.