BACKGROUND It is unclear what morphological features of brain aneurysms are better at predicting risk of rupture. We conducted a meta‐analysis to analyze the best morphological determinants of rupture status. METHODS The Nested Knowledge platform was used to perform a search of articles reporting on aneurysm size, aspect ratio (AR), size ratio (SR), ellipticity index, nonsphericity index, and undulation index. The mean differences between ruptured and unruptured aneurysms were used to calculate effect sizes. RESULTS A total of 63 studies with 13 025 aneurysms were included: 6966 ruptured aneurysms and 6059 unruptured aneurysms. Ruptured aneurysms had a larger size ( P <0.001), AR ( P <0.001), SR ( P <0.001), ellipticity index ( P =0.049), and nonsphericity index ( P =0.049) compared with unruptured aneurysms. The mean size of ruptured aneurysms was 6.1 mm (95% CI, 5.6–6.5). The size of ruptured and unruptured aneurysms was similar in the anterior cerebral artery ( P =0.28), anterior communicating artery ( P =0.31), and basilar artery ( P =0.51). The mean AR of ruptured aneurysms was 1.5 (95% CI, 1.4–1.6), and the mean SR was 2.3 (95% CI, 2.1–2.5). For mirror aneurysms, the mean AR was 1.2 (95% CI, 1.2–1.5), and the mean SR was 2.2 (95% CI, 2.1–2.5). CONCLUSIONS Size is not significantly different between ruptured and unruptured aneurysms located in the anterior cerebral artery, anterior communicating artery, and basilar artery. SR is significantly different between ruptured and unruptured aneurysms in all locations. A mean AR of 1.5 and SR of 2.3 are the thresholds associated with ruptured aneurysm status.

Introduction Untreated brain aneurysms are usually surveilled with serial MR imaging and evaluated with 2D multiplanar measurements. The assessment of aneurysm growth may be more accurate with volumetric analysis. We evaluated the accuracy of a magnetic resonance angiography (MRA) segmentation pipeline for aneurysm volume measurement and surveillance. Methods A pipeline to determine aneurysm volume was developed and tested on two aneurysm phantoms imaged with time-of flight (TOF) MRA and 3D rotational angiography (3DRA). The accuracy of the pipeline was then evaluated by reconstructing 10 aneurysms imaged with contrast enhanced-MRA (CE-MRA) and 3DRA. This calibrated and refined post-processing pipeline was subsequently used to analyse aneurysms from our prospectively acquired database. Volume changes above the threshold of error were considered true volume changes. The accuracy of these measurements was analysed. Results TOF-MRA reconstructions were not as accurate as CE-MRA reconstructions. When compared to 3DRA, CE-MRA underestimated aneurysm volume by 7.8% and did not accurately register the presence of blebs. Eighteen aneurysms (13 saccular and 5 fusiform) were analysed with the optimized 3D volume reconstruction pipeline, with a mean follow-up time of 11 months. Artifact accounted for 10.2% error in volume measurements using serial CE-MRA. When this margin of error was used to assess aneurysms volume in serial imaging with CE-MRA, only two fusiform aneurysms changed in volume. The variations in volume of these two fusiform aneurysms were caused by intra-mural and intrasaccular thrombosis. Conclusions CE-MRA and TOF-MRA 3D volume reconstructions may not register minor morphological changes such as the appearance of blebs. CE-MRA underestimates volume by 7.8% compared to 3DRA. Serial CE-MRA volume measurements had a larger margin of error of approximately 10.2%. MRA-based volumetric measurements may not be appropriate for aneurysm surveillance.

Background and Purpose The degree of internal carotid artery (ICA) stenosis determined by criteria from the North American Symptomatic Carotid Endarterectomy Trial (NASCET) is not the most accurate index to assess distal flow compromise. Distal ICA perfusion is also determined by factors such as tandem carotid stenosis and collateral circulation. Quantification of end-organ ocular perfusion using non-invasive laser speckle flowgraphy (LSFG) may provide insights into distal ICA flow. This study prospectively assessed the degree of ICA flow using LSFG. Methods Eighteen patients with symptomatic carotid stenosis underwent LSFG evaluation. LSFG was used to extract ocular blood flow metrics recorded simultaneously in the retina, choroid, and optic nerve head. The following ocular flow parameters were measured with LSFG: mean blur rate (MBR), flow acceleration index (FAI), and rising rate (RR). Syngo iFlow perfusion imaging was used to objectively quantify contrast flow in the ICA and brain parenchyma during digital subtraction angiography. Time to peak (TTP) and contrast delay were extracted from seven different regions of interest (ROIs). Results MBR, FAI, and RR were correlated with NASCET degree of stenosis. FAI and RR also improved after stenting. TTP improved after stenting in three ROIs. A moderate negative correlation was observed between FAI and contrast delay. Conclusions LSFG non-invasively quantifies end-organ blood flow distal to the ICA origin. LSFG metrics have the potential to quantify end-organ perfusion and determine if a proximal carotid stenosis is symptomatic.

Introduction It is unclear what morphological features of brain aneurysms are better at predicting risk of rupture.We have performed a meta‐analysis to analyze the best morphological determinants of risk of rupture. Methods The Nested Knowledge platformwas used to search thePubMed database for studiesreporting aneurysmal size, aspect ratio (AR), size ratio (SR), ellipticity index (EI), nonsphericity index (NSI) and undulation index (UI).Effect sizes were computed as logarithmically transformed mean differences (MD) between ruptured and unruptured aneurysm. Finally, effect sizes were pooled using random‐effects and inverse‐variance weighting via restricted effects maximum likelihood estimation. Results We included 63 studies with 13,025 aneurysms: ruptured 6966 and unruptured 6059. Ruptured aneurysms were larger compared to unruptured (µ 6.1 mm, 95% CI 5.7‐6.6 vs 4.9 mm, 95% CI 4.5‐5.3 respectively, p < 0.001). There was no significant difference in size between ruptured and unruptured aneurysms in the anterior cerebral artery (ACA, p = 0.28), anterior communicating artery (ACom, p = 0.31) and basilar artety (BA, p = 0.51). AR was significantly higher in ruptured compared to unruptured aneurysms(µ 1.5,95% CI: 1.4‐1.6 vs.1.1, 95% CI: 1.1‐1.2 respectively,p < 0.001).SR was significantly higher in ruptured compared to unruptured aneurysms (µ 2.3,95% CI: 2.1‐2.5 vs. 1.6, 95% CI: 1.4‐1.8 respectively,p < 0.001).Ruptured aneurysms in the ACA and Acom had the largest mean SRs (2.5, 95% CI: 1.0‐ 6.4 and 2.6,95% CI: 2.2‐ 3.0 respectively).NSI and EI were higher in ruptured compared to unruptured aneurysms (p = 0.049 and p = 0.049, respectively). UI was similar in ruptured and unruptured aneurysms (p = 0.22). Conclusions Small aneurysms in the ACA and ACom can rupture regardless of size. SR is the best predictor of rupture status for aneurysms in these locations.SR and AR are predictors of rupture status independently of size.

Introduction: Hemorrhage volume affects the risk of developing complications after aneurysmal subarachnoid hemorrhage (aSAH). This volume is quantified subjectively through the Fisher Scale. We developed an automated method to quantify intracranial hemorrhage and determine the risk of complications after aSAH. Methods: CT scans of patients with aSAH were analyzed. An image-processing algorithm was designed in MATLAB to quantify aSAH volume. The automated algorithm was developed with region-growing and 3D k-means clustering. Two independent raters manually measured hemorrhage volumes using PACS and correlated these measurements with the algorithm measurements in ten patients. Vasospasm and hydrocephalus were identified through chart and imaging review. Hydrocephalus was adjudicated as ventricular enlargement in the setting of aSAH. ROC analysis was performed to evaluate the association between blood volume and the incidence of vasospasm, hydrocephalus and need for a permanent ventriculoperitoneal (VP) shunt. Results: One hundred and forty-one patients were included in the analysis. The intraclass coefficient correlation (ICC) for inter-rater agreement in PACS was 0.988 (p < 0.001). The ICC for comparing automated versus manual volumes was 0.966 (p < 0.001). Bland-Altman analysis reported a mean difference of -3.14 mL between automated and manual measurements. Hemorrhage volume discriminated for the development of vasospasm (AUC = 0.692), hydrocephalus (AUC = 0.775), and need of permanent VP shunt (AUC = 0.669). Conclusion: Vasospasm and hydrocephalus were associated with higher volume of aSAH. Patients with higher volume of aSAH at presentation were more likely to require a permanent VP shunt. An objective method to automatically measure aSAH volume can aid in assessing risk of complications among patients with aSAH.