To characterize the relationship between aneurysm size and epidemiologic risk factors with growth and rupture by using computed tomographic (CT) angiography.
In this HIPAA-compliant, institutional ...review board approved study, patients with known asymptomatic unruptured intracerebral aneurysms were followed up longitudinally with CT angiographic examinations. Growth was defined as an increase in one or more dimensions above the measurement error, and at least 5% volume by using the ABC/2 method. Associations of epidemiologic factors with aneurysm growth and rupture were analyzed by using logistic regression analysis. Intra- and interobserver agreement coefficients for dimension, volume, and growth were evaluated by using the Pearson correlation coefficient and difference of means with 95% confidence intervals, the agreement statistic, and the McNemar χ(2).
Patients (n = 165) with aneurysms (n = 258) had a mean follow-up time of 2.24 years from time of diagnosis. Forty-six of 258 (18%) aneurysms in 38 patients grew larger. Spontaneous rupture occurred in four of 228 (1.8%) intradural aneurysms of average size (6.2 mm). Risk of aneurysm rupture per patient-year was 2.4% (95% CI: 0.5%, 7.12%) with growth and 0.2% (95% CI: 0.006%, 1.22%) without growth (P = .034). There was a 12-fold higher risk of rupture for growing aneurysms (P < .002), with high intra- and interobserver correlation coefficients for size, volume, and growth. Tobacco smoking (3.806, one degree of freedom; P < .015,) and initial size (5.895, two degrees of freedom; P < .051) were independent covariates, predicting 78.4% of growing aneurysms.
These results support imaging follow-up of all patients with aneurysms, including those whose aneurysms are smaller than the current 7-mm treatment threshold. Aneurysm growth, size, and smoking were associated with increased rupture risk.
Object
This study was performed to investigate the risk factors related to the growth of small, asymptomatic, unruptured aneurysms in patients with no history of subarachnoid hemorrhage (SAH).
...Methods
Between January 2005 and December 2010, a total of 508 patients in whom unruptured intracranial aneurysms were diagnosed at the University of California, Los Angeles medical center did not receive treatment to prevent rupture. Of these, 235 patients with no history of SAH who had asymptomatic, small, unruptured aneurysms (< 7 mm) were monitored with 3D CT angiography images. Follow-up images of the lesions were used to measure aneurysm size changes. Patient medical history, family history of SAH, aneurysm size, and location were studied to find the risk factors associated with small aneurysm growth.
Results
A total of 319 small aneurysms were included, with follow-up durations of 29.2 ± 20.6 months. Forty-two aneurysms increased in size during the follow-up; 5 aneurysms grew to become ≥ 7 mm within 38.2 ± 18.3 months. A trend of higher growth rates was found in single aneurysms than in multiple aneurysms (p = 0.07). A history of stroke was the only factor associated with single aneurysm growth (p = 0.03). The number of aneurysms (p = 0.011), number of aneurysms located within the posterior circulation (p = 0.030), and patient history of transient ischemic attack (p = 0.044) were related to multiple aneurysm growth.
Conclusions
Multiple small aneurysms are more likely to grow, and multiple aneurysms located in the posterior circulation may require additional attention. Although single aneurysms have a lower risk of growth, a trend of higher growth rates in single aneurysms was found.
The authors report on their 11 years' experience with embolization of cerebral aneurysms using Guglielmi Detachable Coil (GDC) technology and on the attendant anatomical and clinical outcomes.
Since ...December 1990, 818 patients harboring 916 aneurysms were treated with GDC embolization at University of California at Los Angeles Medical Center. For comparative purposes, the patients were divided into two groups: Group A included their initial 5 years' experience with 230 patients harboring 251 aneurysms and Group B included the later 6 years' experience with 588 patients harboring 665 aneurysms. Angiographically demonstrated complete occlusion was achieved in 55% of aneurysms and a neck remnant was displayed in 35.4% of lesions. Incomplete embolization was performed in 3.5% of aneurysms, and in 5% occlusion was attempted unsuccessfully. A comparison between the two groups revealed a higher complete embolization rate in patients in Group B compared with that in Group A patients (56.8 and 50.2%, respectively). The overall morbidity/mortality rate was 9.4%. Angiographic follow ups were obtained in 53.4% of cases of aneurysms, and recanalization was exhibited in 26.1% of aneurysms in Group A and 17.2% of those in Group B. The overall recanalization rate was 20.9%. Note that recanalization was related to the size of the dome and neck of the aneurysm. Overall incidence of delayed aneurysm rupture was 1.6%, a rate that improved in the past 5 years to 0.5%. Ten of 12 delayed ruptures occurred in large or giant aneurysms.
The clinical and postembolization outcomes in patients treated with the GDC system have improved in the past 5 years. Aneurysm recanalization, however, is still a major limitation of current GDC therapy. Follow-up angiography is mandatory after GDC embolization of cerebral aneurysms. Further technical and device improvements are mandatory to overcome current GDC limitations.
As imaging technology has improved, more unruptured intracranial aneurysms (UIAs) are detected incidentally. However, there is limited information regarding how UIAs change over time to provide ...stratified, patient-specific UIA follow-up management. The authors sought to enrich understanding of the natural history of UIAs and identify basic UIA growth trajectories, that is, the speed at which various UIAs increase in size.
From January 2005 to December 2015, 382 patients diagnosed with UIAs (n = 520) were followed up at UCLA Medical Center through serial imaging. UIA characteristics and patient-specific variables were studied to identify risk factors associated with aneurysm growth and create a predicted aneurysm trajectory (PAT) model to differentiate aneurysm growth behavior.
The PAT model indicated that smoking and hypothyroidism had a large effect on the growth rate of large UIAs (≥ 7 mm), while UIAs < 7 mm were less influenced by smoking and hypothyroidism. Analysis of risk factors related to growth showed that initial size and multiplicity were significant factors related to aneurysm growth and were consistent across different definitions of growth. A 1.09-fold increase in risk of growth was found for every 1-mm increase in initial size (95% CI 1.04-1.15; p = 0.001). Aneurysms in patients with multiple aneurysms were 2.43-fold more likely to grow than those in patients with single aneurysms (95% CI 1.36-4.35; p = 0.003). The growth rate (speed) for large UIAs (≥ 7 mm; 0.085 mm/month) was significantly faster than that for UIAs < 3 mm (0.030 mm/month) and for males than for females (0.089 and 0.045 mm/month, respectively; p = 0.048).
Analyzing longitudinal UIA data as continuous data points can be useful to study the risk of growth and predict the aneurysm growth trajectory. Individual patient characteristics (demographics, behavior, medical history) may have a significant effect on the speed of UIA growth, and predictive models such as PAT may help optimize follow-up frequency for UIA management.
Background
The objective of ischemic stroke (IS) treatment is to achieve revascularization in cerebral arteries to restore blood flow. However, there is no available method to extract arterial flow ...data from clinical CTA images. We developed 3D Stroke Arterial Flow Estimation (SAFE), which provides blood flow data throughout the Circle of Willis based on 3D CTA and allows comparison of arterial flow distribution in the brain.
Methods
We implemented a newly developed 3D vascular reconstruction algorithm for clinical stroke CTA images.
Based on the patient-specific vascular structure, SAFE calculates time-resolved blood flow information for the entire Circle of Willis and allows quantitative flow study of IS cases. Clinical IS cases are presented to demonstrate the feasibility. Four patients with CTA images and CT perfusion data were studied. To validate the SAFE analysis, correlation analysis comparing blood flow at the MCA, ICA, and BA was performed.
Results
Different blood flow patterns were found in individual IS patients. Altered flow patterns and high collateral flow rates were found near occlusions in all cases. Quantitative comparison of blood flow data showed that SAFE obtained flow data and CTP were significantly correlated and provide complementary information about cerebral blood flow for individual patients.
Conclusions
We present SAFE analysis for collecting detailed time-resolved cerebral arterial flow data in the entire Circle of Willis for IS. Further study with more cases may be important to test the clinical utilization of SAFE and helpful to the study of the underlying hemodynamics of stroke.
We analyzed the impact of detailed anatomic characteristics on the results of endovascular coil embolization for anterior communicating artery (AcoA) aneurysms and developed a predictive model ...estimating the probability of successful endovascular treatment.
One hundred eighty-one AcoA aneurysms were treated with endovascular coil embolization between August 1991 and November 2005. Morphological characteristics that were analyzed included direction of the dome, location of the neck, association with hypoplasia or aplasia of AcoA complex vessels, sac, and neck size. Immediate clinical and anatomic results, long-term morbidity/mortality, recanalization rate, and delayed aneurysm thrombosis were analyzed. ORs were calculated for each anatomic and clinical result and logistic regression was used in formulating a predictive model.
There were 115 females and 66 males. Age range was 9 to 86 years (mean 57). Factors significantly associated with complete embolization included small aneurysms (<10 mm), small neck (<4 mm), and anterior dome orientation. Factors significantly associated with aneurysm recanalization after long-term follow-up included aneurysm domes >10 mm, neck location on the AcoA, posterior dome orientation, and incomplete original embolization. Globally, the majority of patients remained neurologically intact or unchanged after the procedure (92.8%). Mortality was significantly influenced by the preoperative condition of the patient. The predictive model successfully represented the likely outcomes based on morphological features.
AcoA aneurysm coil embolization can be safely performed with acceptable rates of morbidity. Dome and neck orientation, sack and neck size, sac-to-neck ratio, and associated anomalies should be considered to accurately assess the probability of successful treatment for AcoA aneurysms.
Abstract
BACKGROUND:
The risk of aneurysm rupture appears to be related to multiple factors such as topology, morphology, size, perianeurysmal environment, and blood flow hemodynamics.
OBJECTIVE:
To ...evaluate aneurysm morphology and to quantitatively compare the volumetric parameters between ruptured and unruptured aneurysms from our clinical database at the UCLA Medical Center.
METHODS:
Novel algorithms that automatically compute aneurysm geometry were tested on the basis of voxel data obtained from angiographic images, and measurements of aneurysm morphology were automatically recorded. We studied a total of 50 aneurysms (25 ruptured and 25 unruptured) with sizes ranging from 3 to 26 mm. To compare the geometric characteristics between ruptured and unruptured groups, we examined measurements, including volume and surface area, and the ratios of these measurements to the minimal bounding sphere around each aneurysm.
RESULTS:
More than 65% of ruptured aneurysms had a ratio of aneurysm volume to bounding sphere volume (AVSV) of > 0.5. More than 70% of ruptured aneurysms had a ratio of aneurysm surface to bounding sphere surface (AASA) of < 1. A trend differentiating ruptured and unruptured aneurysms was observed in AVSV (P = .07) and AASA (P = .04). Classification and regression trees analysis showed 68% correct classification with rupture for AVSV and 70% for AASA.
CONCLUSION:
By comparing aneurysm geometry with the bounding sphere, we found a trend associating the ratios of aneurysm volume and surface area with rupture. These geometric parameters may be useful for understanding the influence of morphology on the risk of aneurysm rupture.
The Los Angeles Motor Scale (LAMS) is a brief 3-item stroke severity assessment measure designed for prehospital and Emergency Department use.
The LAMS and NIHSS were scored in under-12-hour acute ...anterior circulation ischemic stroke patients. Stroke severity ratings were correlated with cervicocerebral vascular occlusion on CTA, MRA, and catheter angiography. Receiver operating curves, c statistics, and likelihood ratios were used to evaluate the predictive value for vascular occlusion of stroke severity ratings.
Among 119 patients, mean age was 67 (+/-18), 45% were male. Time from onset to ED arrival was mean 190 minutes (range 10 to 660). Persisting large vessel occlusions (PLVOs) were present in 62% of patients. LAMS stroke severity scores were higher in patients harboring a vascular occlusion, median 5 (IQR 4 to 5) versus 2 (IQR 1 to 3). Similarly, NIHSS stroke severity scores were higher in PLVO patients, 19 (14 to 24) versus 5 (3 to 7). ROC curves demonstrated that the LAMS was highly effective in identifying patients with PLVOs, c statistic 0.854. At the optimal threshold of 4 or higher, LAMS scores showed sensitivity 0.81, specificity 0.89, and overall accuracy 0.85. LAMS performance was comparable to NIHSS performance (c statistic 0.933). The positive likelihood ratio associated with a LAMS score > or = 4 was 7.36 and the negative likelihood ratio 0.21.
Stroke severity assessed by the LAMS predicts presence of large artery anterior circulation occlusion with high sensitivity and specificity. The LAMS is a promising instrument for use by prehospital personnel to identify select stroke patients for direct transport to Comprehensive Stroke Centers capable of endovascular interventions.
The detailed mechanisms of cerebral aneurysm evolution are poorly understood but are important for objective aneurysm evaluation and improved patient management. The purpose of this study was to ...identify hemodynamic conditions that may predispose aneurysms to growth.
A total of 33 intracranial unruptured aneurysms longitudinally followed with three-dimensional imaging were studied. Patient-specific computational fluid dynamics models were constructed and used to quantitatively characterize the hemodynamic environments of these aneurysms. Hemodynamic characteristics of growing (n=16) and stable (n=17) aneurysms were compared. Logistic regression statistical models were constructed to test the predictability of aneurysm growth by hemodynamic features.
Growing aneurysms had significantly smaller shear rate ratios (p=0.01), higher concentration of wall shear stress (p=0.03), smaller vorticity ratios (p=0.01), and smaller viscous dissipation ratios (p=0.01) than stable aneurysms. They also tended to have larger areas under low wall shear stress (p=0.06) and larger aspect ratios (p=0.18), but these trends were not significant. Mean wall shear stress was not significantly different between growing and stable aneurysms. Logistic regression models based on hemodynamic variables were able to discriminate between growing and stable aneurysms with a high degree of accuracy (94-100%).
Growing aneurysms tend to have complex intrasaccular flow patterns that induce non-uniform wall shear stress distributions with areas of concentrated high wall shear stress and large areas of low wall shear stress. Statistical models based on hemodynamic features seem capable of discriminating between growing and stable aneurysms.
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