Epithelial-mesenchymal transition related genes in unruptured aneurysms identified through weighted gene coexpression network analysis.

Intracranial aneurysm (IA) can cause fatal subarachnoid hemorrhage (SAH) after rupture, and identifying patients with unruptured IAs is essential for reducing SAH fatalities. The epithelial-mesenchymal transition (EMT) may be vital to IA progression. Here, identified key EMT-related genes in aneurysms and their pathogenic mechanisms via bioinformatic analysis. The GSE13353, GSE75436, and GSE54083 datasets from Gene Expression Omnibus were analyzed with limma to identify differentially expressed genes (DEGs) among unruptured aneurysms, ruptured aneurysms, and healthy samples. The results revealed that three EMT-related DEGs (ADIPOQ, WNT11, and CCL21) were shared among all groups. Coexpression modules and hub genes were identified via weighted gene co-expression network analysis, revealing two significant modules (red and green) and 14 EMT-related genes. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses suggested that cytokine interactions were closely related. Gene set enrichment analysis revealed that unruptured aneurysms were enriched for the terms "inflammatory response" and "vascular endothelial growth". Protein-protein interaction analysis identified seven key genes, which were evaluated with the GSE54083 dataset to determine their sensitivity and specificity. In the external validation set, we verified the differential expression of seven genes in unruptured aneurysms and normal samples. Together, these findings indicate that FN1, and SPARC may help distinguish normal patients from patients with asymptomatic IAs.

Intentional Bilateral Renal Artery Coverage During Ruptured Endovascular Paraanastomotic Pseudoaneurysm Repair.

The development of a paraanastomotic pseudoaneurysm is a serious complication after open prosthetic reconstruction of the aorta for occlusive or aneurysmal disease. Open repair of these lesions has previously been associated with high rates of morbidity and mortality. Endovascular repair may provide suitable treatment for proximal paraanastomotic aortic bypass graft pseudoaneurysms in patients who are poor candidates for open surgery. Bilateral renal artery coverage may be necessary to achieve adequate fixation and seal during life-threatening emergency cases of pseudoaneurysm rupture. Due to the infrequency of reported cases, the consequences of bilateral renal artery occlusion during these complex procedures are poorly understood. We present a case of a proximal paraanastomotic aortobifemoral bypass pseudoaneurysm rupture that was managed using endovascular repair with intentional coverage of both renal arteries. We also review the contemporary literature on endovascular management of paraanastomotic aneurysms and discuss the role of bilateral renal artery coverage in treating select patients with complex ruptured aortic pathology.

Newly Identified Hemodynamic Parameter to Predict Thin-Walled Regions of Unruptured Cerebral Aneurysms Using Computational Fluid Dynamics Analysis.

BACKGROUND: The thin-walled regions (TIWRs) of intracranial aneurysms have a high risk of rupture during surgical manipulation. They have been reported to be predicted by wall shear stress and pressure (PS) based on computational fluid dynamics analysis, although this remains controversial. In this study, we investigated whether the oscillatory shear index (OSI) can predict TIWRs. METHODS: Twenty-five unruptured aneurysms were retrospectively analyzed; the position and orientation of the computational fluid dynamics color maps were adjusted to match the intraoperative micrographs. The red area on the aneurysm wall was defined as TIWR, and if most of the regions on the color map corresponding to TIWR were OSI low (lower quartile range), time-averaged wall shear stress (TAWSS) high, or PS high (upper quartile range), each region was defined as a matched region and divided by the total number of TIWRs to calculate the match rate. In addition, the mean values of OSI, TAWSS, and PS corresponding to TIWRs were quantitatively compared with those in adjacent thick-walled regions. RESULTS: Among 27 TIWRs of 25 aneurysms, 23, 10, and 14 regions had low OSI, high TAWSS, and high PS regions (match rate: 85.2%, 37.0%, and 51.9%), respectively. Receiver operating characteristic curve analysis demonstrated that OSI was the most effective hemodynamic parameter (area under the curve, 0.881), followed by TAWSS (0.798). Multivariate analysis showed that OSI was a significant independent predictor of TIWRs (odds ratio, 18.30 [95% CI, 3.2800-102.00], P < 0.001). CONCLUSIONS: OSI may be a unique predictor for TIWRs. Low OSI strongly corresponds with TIWRs of intracranial aneurysms.

Flow Diversion in Acute Sub Arachnoid Haemorrhage: A Single Centre Five Year Experience.

OBJECTIVES: The role of flow-diversion in acute sub-arachnoid haemorrhage (SAH) is controversial. Many of the published data warns of high rates of procedure-related complications and aneurysmal rebleed. This study evaluates the safety, efficacy, clinical and angiographic outcomes of acute flow-diversion at our institute. METHODS: The institutional database from June 2015 to June 2020 was retrospectively reviewed for aneurysmal SAH (aSAH) treated with flow diversion. Clinical presentation, procedural details, complications, anti-platelet usage, rebleeding and aneurysm occlusion rates and outcomes were recorded. RESULTS: 22 (59% females; median age 56 years) consecutive patients were identified. None of them were on regular antiplatelets/anticoagulation in the 15-days preceding the treatment. The mean aneurysm diameter was 5.4 mm and the median delay to flow-diversion was 2 days. Almost 73% (16/22) of patients had adjunctive coiling in the same session. There was no aneurysmal rebleed at a median follow up of 8.5 months and 86.3% (19/22 patients) had good clinical outcomes (3-month MRS 0-2). Adverse events related to the flow diversion procedure were seen in 3 patients; none of them had a medium to long-term clinical consequence. Three patients died from complications of SAH, unrelated to the procedure. Vascular imaging follow-up was available for 20 patients and the complete aneurysm occlusion rate was 95%. CONCLUSION: Flow-diversion could be a reasonably safe and effective technique for treating ruptured aneurysms in appropriately selected patients when conventional options of surgical clipping and coiling are considered challenging.

Enigma of what is Known about Intracranial Aneurysm Occlusion with Endovascular Devices.

Aneurysmal subarachnoid Hemorrhage is a major cause of neurological morbidity and mortality. Over the years vascular neurosurgery has witnessed technological advances aimed to reduce the morbidity and mortality. Several endovascular devices have been used in clinical practice to achieve this goal in the management of ruptured and unruptured cerebral aneurysms. Recurrence due to recanalization is encountered in all of these endovascular devices as well as illustrated by Barrow Ruptured Aneurysm Trial. Histological and molecular characterization of the aneurysms treated with endovascular devices is an area of active animal and human research studies. Yet, the pathobiology illustrating the mechanisms of aneurysmal occlusion and healing lacks evidence. The enigma of aneurysmal healing following treatment with endovascular devices needs to be de-mystified to understand the biological interaction of endovascular device and aneurysm and thereby guide the future development of endovascular devices aimed at better aneurysm occlusion. We performed a comprehensive and detailed literature review to bring all the known facts of the pathobiology of intracranial aneurysm healing, the knowledge of which is of paramount importance to neurosurgeons, an interventional neuroradiologist, molecular biologist, geneticists, and experts in animal studies. This review serves as a benchmark of what is known and platform for future studies basic science research related to intracranial aneurysms.

Cross-over Deployment of a Tapered Stent Graft to Repair a Ruptured Isolated Internal Iliac Aneurysm.

We report the case of a 72-year-old man who presented with a left ruptured internal iliac aneurysm (IIA). A percutaneous cross-over approach was used to coil-embolize the 3 distal branches of the IIA. A tapered endograft limb was then delivered via the right common femoral artery using a femorofemoral through-and-through cross-over approach. The widest part of the graft was deployed in the common iliac artery and the smallest in the external iliac artery. This percutaneous endovascular technique opens up new perspectives in emergency care for ruptured internal iliac artery aneurysms.

Clinical and radiological outcomes in relation with the anatomical orientation of clipped middle cerebral artery bifurcation aneurysms.

BACKGROUND: The middle cerebral artery (MCA) bifurcation represents the most frequent location for intracranial aneurysms. Often, the aneurysmal dome can hide the origin of perforating arteries from the M1 segment during the surgical clipping causing ischemic lesions and worse clinical outcome. The aim of this paper is to analyze the association between the orientation of the aneurysm sac and the clinical and radiological outcomes after surgical clipping. METHODS: Data from 50 MCA bifurcation clipped aneurysms in 47 patients were collected retrospectively. Three different groups were identified according to the aneurysmal sac orientation: anterior-inferior, posterior and superior. A possible association between the aneurysmal sac projection and the outcome was searched through a univariable logistic regression analysis. RESULTS: Statistical analysis showed significant correlation between the radiologic evidence of post-operative ischemia in the posterior group (p = 0.046, RR = 1.65) and an increased risk in the superior orientation group (p = 0.145, RR = 1.38). The anterior-inferior group was, instead, significantly associated with no evidence of radiologic ischemia (p = 0.0019, RR = 0.58). CONCLUSION: The orientation of the aneurysmal dome and sac represents a fundamental feature to be considered during the surgical clipping of the MCA aneurysms. Indeed, its posterior and superior projection is associated with a higher incidence of radiologic ischemic lesions due to the origin of perforating arteries from M1 segment behind the aneurysmal sac. The anterior-inferior orientation, on the contrary, is associated with a lower risk.

Experience of managing superior mesenteric artery aneurysm and its midterm follow-up results with 18 cases.

OBJECTIVES: To characterize the clinical features, treatment, and prognosis of superior mesenteric artery aneurysms and provide evidence for clinical decision-making. METHODS: We retrospectively reviewed the diagnosis and treatment of 18 cases of superior mesenteric artery aneurysm admitted to our center from 2003 to 2020, including demographic data, risk factors, clinical manifestations, diagnosis, treatment strategies, and follow-up results. RESULTS: The average age of the patients was 49.1 years, and males accounted 83.3%. The development of the disease was associated with infection, hypertension, pancreatitis, and trauma, but no significant associations with atherosclerosis were noted by our results. Nine patients were diagnosed with true aneurysm, seven patients with pseudoaneurysm, and two patients with dissecting aneurysm. Rupture of aneurysm occurred in three patients (16.7%), and one of them died before surgery. The surgery success rate was 94.1%, and open surgery was performed on nine patients, endovascular surgery on three patients, and conservative treatment on three patients. The follow-up rate was 77.8% (14/18), and the average follow-up time was 48.2 months. The mortality and reintervention rate during follow-up was 0. The two-year patency rate of artificial vessels and covered stents was 50%. CONCLUSION: The clinical manifestations and features of superior mesenteric artery aneurysms vary between patients. Careful evaluation of vascular anatomy and personalized treatment strategy are critical in the management of superior mesenteric artery aneurysms. Midterm follow-up results of superior mesenteric artery aneurysms are satisfactory.

Hemodynamic conditions that favor bleb formation in cerebral aneurysms.

BACKGROUND: Although it is generally believed that blebs represent weaker spots in the walls of intracranial aneurysms (IAs), it is largely unknown which aneurysm characteristics favor their development. OBJECTIVE: To investigate possible associations between aneurysm hemodynamic and geometric characteristics and the development of blebs in intracranial aneurysms. METHODS: A total of 270 IAs in 199 patients selected for surgical clipping were studied. Blebs were visually identified and interactively marked on patient-specific vascular models constructed from presurgical images. Blebs were then deleted from the vascular reconstruction to approximate the aneurysm before bleb formation. Computational fluid dynamics studies were performed in these models and in cases without blebs. Hemodynamic and geometric characteristics of aneurysms with and without blebs were compared. RESULTS: A total of 173 aneurysms had no blebs, while 97 aneurysms had a total of 122 blebs. Aneurysms favoring bleb formation had stronger (p<0.0001) and more concentrated inflow jets (p<0.0001), higher flow velocity (p=0.0061), more complex (p<0.0001) and unstable (p=0.0157) flow patterns, larger maximum wall shear stress (WSS; p<0.0001), more concentrated (p=0.0005) and oscillatory (p=0.0004) WSS distribution, and a more heterogeneous WSS field (p<0.0001), than aneurysms without blebs. They were also larger (p<0.0001), more elongated (p<0.0001), had wider necks (p=0.0002), and more distorted and irregular shapes (p<0.0001). CONCLUSIONS: Strong and concentrated inflow jets, high-speed, complex, and unstable flow patterns, and concentrated, oscillatory, and heterogeneous WSS patterns favor the formation of blebs in IAs. Blebs are more likely to form in large, elongated, and irregularly shaped aneurysms. These adverse characteristics could be considered signs of aneurysm instability when evaluating aneurysms for conservative observation or treatment.

Hemodynamics in aneurysm blebs with different wall characteristics.

BACKGROUND: Blebs are important secondary structures of intracranial aneurysms associated with increased rupture risk and can affect local wall stress and hemodynamics. Mechanisms of bleb development and evolution are not clearly understood. We investigate the relationship between blebs with different wall characteristics and local hemodynamics and rupture sites. METHODS: Blebs with different wall appearances in intra-operative videos were analyzed with image-based computational fluid dynamics. Thin red blebs were compared against thick atherosclerotic/hyperplastic white/yellow blebs. Rupture points were identified in videos of ruptured aneurysms harboring blebs. RESULTS: Thin blebs tended to be closer to the inflow than atherosclerotic blebs of the same aneurysm (P=0.0234). Blebs near the inflow had higher velocity (P=0.0213), vorticity (P=0.0057), shear strain rate (P=0.0084), wall shear stress (WSS) (P=0.0085), and WSS gradient (P=0.0151) than blebs far from the inflow. In a subset of 12 ruptured aneurysms harboring blebs, rupture points were associated with thin blebs in 42% of aneurysms, atherosclerotic blebs in 25%, and were away from blebs in the remaining 33%. CONCLUSIONS: Not all blebs are equal; some have thin translucent walls while others have thick atherosclerotic walls. Thin blebs tend to be located closer to the inflow than atherosclerotic blebs. Blebs near the inflow are exposed to stronger flows with higher and spatially variable WSS than blebs far from the inflow which tend to have uniformly lower WSS. Aneurysms can rupture at thin blebs, atherosclerotic blebs, and even away from blebs. Further study of wall failure in aneurysms with different bleb types is needed.

Hemodynamic Force as a Potential Regulator of Inflammation-Mediated Focal Growth of Saccular Aneurysms in a Rat Model.

Past studies have elucidated the crucial role of macrophage-mediated inflammation in the growth of intracranial aneurysms (IAs), but the contributions of hemodynamics are unclear. Considering the size of the arteries, we induced de novo aneurysms at the bifurcations created by end-to-side anastomoses with the bilateral common carotid arteries in rats. Sequential morphological data of induced aneurysms were acquired by magnetic resonance angiography. Computational fluid dynamics analyses and macrophage imaging by ferumoxytol were performed. Using this model, we found that de novo saccular aneurysms with a median size of 3.2 mm were induced in 20/45 (44%) of animals. These aneurysms mimicked human IAs both in morphology and pathology. We detected the focal growth of induced aneurysms between the 10th and 17th day after the anastomosis. The regional maps of hemodynamic parameters demonstrated the area exposed to low wall shear stress (WSS) and high oscillatory shear index (OSI) colocalized with the regions of growth. WSS values were significantly lower in the growing regions than in ones without growth. Macrophage imaging showed colocalization of macrophage infiltration with the growing regions. This experimental model demonstrates the potential contribution of low WSS and high OSI to the macrophage-mediated growth of saccular aneurysms.

The Woven EndoBridge (WEB) Versus Conventional Coiling for Treatment of Patients with Aneurysmal Subarachnoid Hemorrhage: Propensity Score-Matched Analysis of Clinical and Angiographic Outcome Data.

OBJECTIVE: Conventional coiling is standard for treatment of ruptured intracranial aneurysms. We compared clinical and angiographic outcomes between intrasaccular flow disruption with the Woven EndoBridge (WEB) and conventional coiling in patients with aneurysmal subarachnoid hemorrhage (aSAH) using a propensity score-matched analysis. METHODS: This is a retrospective study of consecutive patients with aSAH treated with the WEB or conventional coiling between 2010 and 2019. Baseline characteristics, procedural complications, angiographic results, and functional outcome were compared between both groups. RESULTS: Fifty-two patients treated with the WEB and 236 patients treated by coiling were included. The WEB group was characterized by a higher patient age (P = 0.024), a wider aneurysm neck (P < 0.001), and more frequent location at the posterior circulation (P = 0.004). Procedural complications were comparable between WEB (19.2%) and coiling (22.7%, P = 0.447). In-hospital mortality rates were higher in the coiling group (WEB: 5.8%, coiling: 17.8%; P = 0.0034). Favorable outcome (modified Rankin scale ≤2) was obtained in 51.3% after WEB embolization and in 55.0% after coiling (P = 0.653). Retreatment was performed in 26.4% of patients after WEB and in 25.8% after coiling (P = 0.935). Propensity score analysis confirmed these results and revealed higher adequate occlusion rates at midterm follow-up for WEB-treated aneurysms (WEB: 93.9%, coiling: 76.2%, P = 0.058). CONCLUSIONS: Compared with conventional coiling, aSAH patients treated with the WEB have a similar clinical and potentially improved angiographic outcome at midterm follow-up. The WEB might be considered as an alternative to conventional coiling for the treatment of RIAs, in particular for those with wide-necked and thus challenging anatomy.

Long-term outcomes of endovascular treatment of isolated subclavian artery aneurysms.

OBJECTIVES: The aim of the present study was to review our institutional experience of endovascular treatment for isolated subclavian artery aneurysms and evaluate the long-term outcomes. METHODS: A retrospective review of all patients with isolated subclavian artery aneurysms who underwent endovascular treatment between March 2008 and March 2020 was performed. The demographics, aneurysmal characteristics, treatment strategies, and in-hospital and follow-up outcomes were recorded and then analyzed. RESULTS: From March 2008 to March 2020, 35 isolated subclavian artery aneurysms were endovascularly treated at our institution. Atherosclerosis was the most common cause of aneurysms in this series. Most aneurysms were intrathoracic (91.4%) and located at the right side (77.1%). There were 26 true aneurysms, seven pseudoaneurysms, and two ruptured isolated subclavian artery aneurysms. Five types of endovascular strategies were performed. Covered stent placement across the aneurysm was the most (54.3%) commonly used method. Technical success was achieved in all patients. The median postoperative in-hospital stay was 4.0 days (range, 1-15 days). One patient died after discharge but within 30 days of surgery due to myocardial infarction. The median follow-up time was 62.0 months (range, 3-132 months). No death, stroke, stent fractures, or severe upper limb ischemia developed during the follow-up period. The cumulative survival rate at five years was 97.1%. The overall complication rate was 25.7% and one-third of complications (8.6%) required reinterventions. CONCLUSIONS: Endovascular treatment for isolated subclavian artery aneurysms is safe, effective and technically achievable in most patients. Short- and long-term outcomes are promising. Reasonable and flexible use of covered stents can also get satisfactory outcomes in some complicated lesions such as isolated subclavian artery aneurysms located at the origin of the right subclavian artery, avoiding the huge surgical trauma caused by conventional open repair.

Effect of bifurcation in the hemodynamic changes and rupture risk of small intracranial aneurysm.

The role of bifurcations is prominent in the intracranial aneurysm (IA) evaluation, and there are many contradictions and complexities in the rupture risk of small IA. Therefore, in the present study, the effect of bifurcation on the manner of hemodynamic changes and the rupture risk of the small middle cerebral artery (MCA) aneurysm is investigated. 3D anatomical models of the MCAs of 21 healthy subjects, 19 patients/IA/bifurcation, and 19 patients/IA were generated, and the models were analyzed by the computational fluid dynamic (CFD) analysis. The presence of bifurcation in the pathway of the blood flow in the parent artery of healthy subjects has reduced the maximum velocity, flow rate, and wall shear stress (WSS) by 25.8%, 38.6%, and 11.1%, respectively. The bifurcation decreased the maximum velocity and flow rate in the neck and sac of the aneurysm by 1.65~2.1 times, respectively. It increased the maximum WSS, and phase lag between the WSS graph of healthy subjects and patients by 12.8%~13.9% and 10.2%~40.4%, respectively. The effect of bifurcation on the Womersley number change in the aneurysm was insignificant, and the blood flow was in the laminar flow condition in all samples. The results also showed bifurcation increased the phase lag between the flow rate and pressure gradient graphs up to approximately 1.5 times. The rupture prediction index for patients/IA/bifurcation and patients/IA was 62.1%(CV = 4.1) and 51.8%(CV = 4.4), respectively. Thus, in equal conditions, the presence of bifurcation increased the probability of the rupture of the aneurysm by 19.9%.

Association between sleep duration and rupture of intracranial aneurysms: A single-center retrospective study.

OBJECTIVE: To assess the relationship between sleep duration and risk of rupture of intracranial aneurysms (IAs). METHODS: According to our inclusion and exclusion criteria, 683 patients admitted to Beijing Tiantan Hospital were included in this study. There were 201 patients in the ruptured group and 482 patients in the unruptured group. Sleep duration was divided into three levels: ≥8 h (long), 6-8 h (normal), ≤6 h (short). Correlation between different sleep duration and rupture of IAs was evaluated by univariate and multivariate regression analysis. RESULTS: The results of multivariate analysis demonstrated that there was a statistical difference between sleep duration of ≤6 h and sleep duration ≥8 h (OR = 1.76, CI = [1.08-2.87], p = 0.025). There was no statistically significant difference between the group with sleep duration of 6-8 h and sleep duration of ≥8 h (OR = 1.04, CI = [0.65-1.67], p = 0.857). CONCLUSION: Short sleep duration (≤6 h) may be related to the rupture of intracranial aneurysms. The reason for this correlation is not yet clear. We suspect that it may be caused by a series of physiological changes caused by reduced sleep.

Impact of Ruptured Aneurysm Circulation on Mortality: A Nationwide Inpatient Sample Analysis.

OBJECTIVE: This study investigates the effect of aneurysm circulation on mortality and patient outcomes after aneurysmal subarachnoid hemorrhage (SAH) within the United States. METHODS: A retrospective cohort study was conducted using the Nationwide Inpatient Sample (NIS), a part of the Healthcare Cost and Utilization Project (HCUP), with ICD-10 codes for non-traumatic SAH between 2015-2016. Aneurysms were stratified as either anterior or posterior circulation. Multivariate logistic regression was used to find the impact of selected variables on the odds of mortality. RESULTS: The NIS reported 1,892 cases of non-traumatic SAH within the study period that were predominantly anterior circulation (82.6%), female (68.6%), white (57.7%), with mean age of 59.07 years, and in-hospital mortality of 21.4%. Anterior circulation aneurysms were associated with lower severity of initial illness (p = 0.014) but higher likelihood of vasospasm (p = 0.0006) than those of the posterior circulation. In a multivariate logistic regression analysis, mortality was associated with posterior circulation aneurysms (OR: 1.42; CI 95% 1.005-20.10, p = 0.047), increasing age (OR: 1.035; 95% CI 1.022-1.049; p < 0.0001), and shorter hospital stays (OR: 0.7838; 95% CI 0.758-0.811; p < 0.0001). Smoking history (OR: 0.825; 95% CI 0.573-1.187, p > 0.05) and vasospasm (OR: 1.005; 95% CI 0.648-1.558; p > 0.05) were not significantly associated with higher odds of mortality. CONCLUSIONS: Mortality following aneurysmal SAH is associated with posterior circulation aneurysms, and increasing age, but not smoking history or vasospasm. These findings may be useful for prognostication and counseling patients and families.

Outcomes of treatment modalities for ruptured intracranial aneurysms based on age - A meta-analysis.

BACKGROUND: Data comparing the effect of age on outcomes of patients who underwent either endovascular coiling (EVC) or neurosurgical clipping (NSC) for ruptured intracranial aneurysms remains limited. OBJECTIVE: To better elucidate the preferred intervention for ruptured aneurysm management by presenting the results of our systematic review of the literature that evaluated the potential advantages of the two interventions between different age groups. METHODS: Systematic review of PubMed and Embase was performed (2002 - June 10, 2019) following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2013 guidelines. Median ages of EVC and NSC cohorts were 54 and 56, respectively. Ages below the median were used in our "younger" cohort; ages above the median were used in our "older" cohort. RESULTS: We reviewed 13 studies on 7,137 patients. In the younger cohort, there were 2840 (EVC: 1412, NSC: 1428) patients. In the older cohort, there were 4297 (EVC: 2552, NSC: 1745) patients. Overall, there was a significant difference in functionality between EVC (77.70%) and NSC (69.23%) (OR=1.69; 95% C.I.: 1.10-2.60, p = 0.0212). In our younger cohort, functionality was significantly different between EVC (77%) and NSC (69%) (OR=1.54; 95% C.I.: 1.29-1.84, p < 0.001). For the older cohort, there was no significant difference in functionality, complications, or efficacy. CONCLUSIONS: We have highlighted the importance of considering age prior to deciding which intervention is most appropriate for ruptured aneurysms, with higher morbidity and mortality with NSC versus EVC in the younger population.

Age and morphology of posterior communicating artery aneurysms.

Risk of intracranial aneurysm rupture could be affected by geometric features of intracranial aneurysms and the surrounding vasculature in a location specific manner. Our goal is to investigate the morphological characteristics associated with ruptured posterior communicating artery (PCoA) aneurysms, as well as patient factors associated with the morphological parameters. Three-dimensional morphological parameters in 409 patients with 432 PCoA aneurysms diagnosed at the Brigham and Women's Hospital and Massachusetts General Hospital between 1990 and 2016 who had available CT angiography (CTA) or digital subtraction angiography (DSA) were evaluated. Morphological parameters examined included aneurysm wall irregularity, presence of a daughter dome, presence of hypoplastic or aplastic A1 arteries and hypoplastic or fetal PCoA, perpendicular height, width, neck diameter, aspect and size ratio, height/width ratio, and diameters and angles of surrounding parent and daughter vessels. Univariable and multivariable statistical analyses were performed to determine the association of morphological parameters with rupture of PCoA aneurysms. Additional analyses were performed to determine the association of patient factors with the morphological parameters. Irregular, multilobed PCoA aneurysms with larger height/width ratios and larger flow angles were associated with ruptured PCoA aneurysms, whereas perpendicular height was inversely associated with rupture in a multivariable model. Older age was associated with lower aspect ratio, with a trend towards lower height/width ratio and smaller flow angle, features that are associated with a lower rupture risk. Morphological parameters are easy to assess and could help in risk stratification in patients with unruptured PCoA aneurysms. PCoA aneurysms diagnosed at older age have morphological features associated with lower risk.

A pilot study using a machine-learning approach of morphological and hemodynamic parameters for predicting aneurysms enhancement.

PURPOSE: The development of straightforward classification methods is needed to identify unstable aneurysms and rupture risk for clinical use. In this study, we aim to investigate the relative importance of geometrical, hemodynamic and clinical risk factors represented by the PHASES score for predicting aneurysm wall enhancement using several machine-learning (ML) models. METHODS: Nine different ML models were applied to 65 aneurysm cases with 24 predictor variables. ML models were optimized with the training set using tenfold cross-validation with five repeats with the area under the curve (AUC) as cost parameter. Models were validated using the test set. Accuracy being significantly higher (p < 0.05) than the non-information rate (NIR) was used as measure of performance. The relative importance of the predictor variables was determined from a subset of five ML models in which this information was available. RESULTS: Best-performing ML model was based on gradient boosting (AUC = 0.98). Second best-performing model was based on generalized linear modeling (AUC = 0.80). The size ratio was determined as the dominant predictor for wall enhancement followed by the PHASES score and mean wall shear stress value at the aneurysm wall. Four ML models exhibited a statistically significant higher accuracy (0.79) than the NIR (0.58): random forests, generalized linear modeling, gradient boosting and linear discriminant analysis. CONCLUSIONS: ML models are capable of predicting the relative importance of geometrical, hemodynamic and clinical parameters for aneurysm wall enhancement. Size ratio, PHASES score and mean wall shear stress value at the aneurysm wall are of highest importance when predicting wall enhancement in cerebral aneurysms.

Discrimination of intracranial aneurysm rupture status: patient-specific inflow boundary may not be a must-have condition in hemodynamic simulations.

BACKGROUND: Computational fluid dynamics (CFD) are important in evaluating the hemodynamics of intracranial aneurysm rupture, and the setting of inflow boundary conditions is critical. We evaluated intracranial aneurysm hemodynamics based on generalized versus patient-specific inflow boundary conditions to examine the effect of different hemodynamic results on the discrimination of intracranial aneurysm rupture status. METHODS: We enrolled 148 patients with 156 intracranial aneurysms. For each included aneurysm, we performed CFD simulation once based on patient-specific and once based on generalized inflow boundary conditions. First, we compared the hemodynamics of intracranial aneurysms based on different inflow boundary conditions. Then, we divided the included aneurysms into a ruptured and unruptured group and compared the hemodynamics between the two groups under patient-specific and generalized inflow boundary conditions. RESULTS: For the hemodynamic parameters using specific inflow boundary conditions, more complex flow (p = 0.002), larger minimum WSS (p = 0.024), lower maximum low WSS area (LSA) (p = 0.038), and oscillatory shear index (p = 0.002) were found. Furthermore, we compared the hemodynamics between ruptured and unruptured groups based on different inflow boundary conditions. We found that the significant hemodynamic parameters associated with rupture status were the same, including the proportion of aneurysms with flow complex and unstable flow and the minimum and maximum of LSA (p = 0.011, p = 0.003, p = 0.001 and p = 0.004, respectively). CONCLUSION: Patient-specific and generalized inflow boundary conditions of aneurysmal hemodynamics resulted in significant differences. However, the significant parameters associated with rupture status were the same in both conditions, indicating that patient-specific inflow boundary conditions may not be necessary for predicting rupture risk.