Smaller Neck Diameter Research Articles

Risk factors for the rupture of mirror middle cerebral artery aneurysm using computer-assisted semiautomated measurement and hemodynamic analysis

ObjectivesTo identify the morphologic and hemodynamic risk factor of mirror middle cerebral artery (MCA) aneurysms. MethodsWe conducted a retrospective analysis of 40 paired mirror MCA aneurysms. Aneurysms were divided into ruptured and unruptured groups. Seventeen morphological and nine hemodynamic parameters were measured using computer-assisted semiautomated measurement (CASAM) and computer flow dynamic (CFD) simulation. We performed a paired t-test (for normally distributed data) or a paired Wilcoxon rank-sum (for non-normally distributed data) to analyze all parameters between the groups. Multivariate conditional logistic regression analysis identified independent risk factors. The receiver operating characteristic curve was analyzed to acquire the area under the curve (AUC) and the cutoff values of the independent risk factors. ResultsThere were significant differences in morphological and hemodynamic parameters between the ruptured and unruptured mirror aneurysms. The multivariate logistic analysis showed that the greater size (odds ratio [OR] = 9.807, p = 0.003), smaller neck diameter (OR = 0.285, p = 0.018) and maximum oscillatory shear index (OSI) (OR = 0.000001, p = 0.046) were independently correlated with aneurysm rupture. AUCs for size, N. and maximum OSI were 0.794, 0.695, and 0.701, respectively. The cutoff values of the size, neck diameter, and maximum OSI were 6.30, 5.07, and 0.356437, respectively. ConclusionsMorphology and hemodynamics can help predict aneurysm rupture risks. The more significant size, smaller neck diameter and maximum OSI were independent risk factors for the rupture of MCA aneurysms. The variables could aid practical risk evaluation.

Tobacco use and age are associated with different morphologic features of anterior communicating artery aneurysms

We present a cohort of patients with anterior communicating artery (ACoA) aneurysms to investigate morphological characteristics and clinical factors associated with rupture of the aneurysms. 505 patients with ACoA aneurysms were identified at the Brigham and Women’s Hospital and Massachusetts General Hospital between 1990 and 2016, with available CT angiography (CTA). Three-dimensional (3D) reconstructions were performed to evaluate aneurysmal morphologic features, including location, projection, irregularity, the presence of daughter dome, height, height/width ratio, and relationships between surrounding vessels. Patient risk factors assessed included patient age, sex, tobacco use, alcohol use, and family history of aneurysms and aneurysmal subarachnoid hemorrhage. Logistic regression was used to build a predictive ACoA score for rupture. Morphologic features associated with ruptured ACoA aneurysms were the presence of a daughter dome (OR 21.4, 95% CI 10.6–43.1), smaller neck diameter (OR 0.55, 95% CI 0.42–0.71), larger aspect ratio (OR 3.57, 95% CI 2.05–6.24), larger flow angle (OR 1.03, 95% CI 1.02–1.05), and smaller ipsilateral A2-ACoA angle (OR 0.98, 95% CI 0.97–1.00). Tobacco use was predominantly associated with morphological factors intrinsic to the aneurysm that were associated with rupture while younger age was also associated with morphologic features extrinsic to the aneurysm that were associated with rupture. The ACoA score had good predictive capacity for rupture with AUC = 0.92 using the 0.632 bootstrap cross-validation for correction of overfitting bias. Ruptured ACoA aneurysms were associated with morphological features that are simple to assess using a simple scoring system. Tobacco use and younger age were predominantly associated with intrinsic and extrinsic morphological features characteristic of rupture, respectively.

Suitability of the Aortic Neck Anatomy for Endovascular Aneurysm Repair in Korean Patients with Abdominal Aortic Aneurysm.

PurposeTo evaluate the aortic neck anatomy in Korean patients with abdominal aortic aneurysms (AAAs).Materials and MethodsWe examined computed tomography scans of 343 patients with AAAs (≥5.5 cm for men or ≥5 cm for women) between 2009 and 2018. Eligibility of neck anatomy for endovascular aneurysm repair (EVAR) was assessed with the standard instructions for use (IFU) (length ≥15 mm, suprarenal angulation (SRA) ≤45°, infrarenal angulation (IRA) ≤60°, and diameter 18-32 mm) and the extended IFU (length ≥10 mm, SRA ≤60°, IRA ≤75°, and diameter 17-32 mm).ResultsThere were 71 women (20.7%), and 61 patients (17.8%) with rupture. Women had smaller neck diameters (21.3 vs. 23.4 mm, P<0.001 for proximal neck; 22.2 vs. 24.5 mm, P<0.001 for distal neck), and higher angulations (51.5° vs. 37.8°, P<0.001 for SRA; 77.7° vs. 57.0°, P<0.001 for IRA) than men. However, the neck length was not significantly different. Patients with ruptured AAAs had shorter neck lengths (21.0 vs. 26.8 mm, P=0.005) than those with intact AAAs. However, the neck diameters and angulations were not significantly different. EVAR eligibility for standard and extended IFUs was found in 37.5% and 55.1% of men, and 11.3% and 25.4% of women (P<0.001 for both IFUs); neck anatomy was eligible in 34.0% of intact AAAs and 23.0% of ruptured AAAs (P=0.098).ConclusionA significant proportion of the Korean patients did not meet the IFU for EVAR, mainly due to the angulated neck. Women, and patients with ruptured AAAs, were less likely to meet the IFU criteria.

Relationship between bending strength of bulk porous silicon carbide ceramics and grain boundary strength measured using microcantilever beam specimens

The relationship between the bending strength of bulk porous SiC ceramics and the grain boundary strength measured using microcantilever beam specimens of SiC bicrystals was investigated. The average value of the grain boundary strength was 39.2 GPa, and its higher value was roughly equal to that derived using an ab-initio calculation. The strengths of the specimens having only one neck were estimated by analyzing the effect of the specimen size on the strength of bulk porous SiC ceramics and by also analyzing the grain boundary strength and the stress concentration at the neck surface. The estimated strengths were generally consistent of the order of several hundred MPa, meaning that the strength of porous SiC ceramics should be dependent on the stress concentration at the neck and the grain boundary strength. Furthermore, they were in a better agreement using smaller neck curvature, smaller neck diameter, and lower grain boundary strength.