Yonsei Med J.  2016 Sep;57(5):1178-1184. 10.3349/ymj.2016.57.5.1178.

Risk Factors for the Rupture of Bifurcation Intracranial Aneurysms Using CT Angiography

• Wang GX
• Zhang D
• Wang ZP
• Yang LQ
• Zhang L
• Wen L

• KMID: 2374163
• DOI: http://doi.org/10.3349/ymj.2016.57.5.1178

Abstract

PURPOSE
To investigate the clinical and morphological characteristics in relation to risk of bifurcation intracranial aneurysm rupture.
MATERIALS AND METHODS
Data from 202 consecutive patients with 219 bifurcation aneurysms (129 ruptured and 90 unruptured) managed at the authors' facility between August 2011 and July 2014 were retrospectively reviewed. Based on their clinical records and CT angiographic findings, the ability of risk factors to predict aneurysm rupture was assessed using statistical methods.
RESULTS
Age, hypertension, diabetes mellitus, and cerebral atherosclerosis were negatively correlated with aneurysm rupture. Aneurysms located in the middle cerebral artery, daughter artery ratio, lateral angle ratio (LA ratio), and neck width were negatively correlated with rupture. Aneurysms located in the anterior communicating artery, irregularity, with daughter sac, depth, width, maximum size, aspect ratio (AR), depth-to-width ratio, and bottleneck factor were significantly and positively correlated with rupture. Binary logistic regression model revealed that irregular shape [odds ratio (OR) 6.598] and AR (OR 3.507) strongly increased the risk of bifurcation aneurysm rupture, while age (OR 0.434), cerebral atherosclerosis (OR 0.125), neck width (OR 0.771), and LA ratio (OR 0.267) were negatively correlated with rupture (p<0.05). Receiver operating characteristic analysis revealed the threshold values of AR and LA ratio to be 1.18 and 1.50, respectively.
CONCLUSION
Age (≥60 yr), cerebral atherosclerosis, and aneurysms with a larger neck width and larger LA ratio are protective factors against bifurcation aneurysm rupture. An aneurysm with an irregular shape and an increased AR reflect the greater likelihood of a rupture.

Keyword

Intracranial aneurysm; rupture; risk factors; subarachnoid hemorrhage; computed tomography; angiography

MeSH Terms

Adult
Age Factors
Aged
Aged, 80 and over
Aneurysm, Ruptured/*diagnostic imaging
Cerebral Angiography/*methods
*Computed Tomography Angiography
Developmental Disabilities
Diabetic Angiopathies/complications
Female
Humans
Hypertension/complications
Intracranial Aneurysm/*diagnostic imaging
Intracranial Arteriosclerosis/complications
Logistic Models
Male
Middle Aged
Middle Cerebral Artery/diagnostic imaging
Odds Ratio
Protective Factors
ROC Curve
Retrospective Studies
Risk Factors

Figure

• 

  Fig. 1 The image of an aneurysm is classified as a classical neck type (Type C). The larger DA is defined as DA A, and the other DA is defined as DA B. LA mean diameter of the vessel measure at the LA1 and LA2, and the other vessel is measured as LB; the DA ratio is defined as LA/LB. The angle between the parent artery and DA A is defined as angle A, and the angle between the parent artery and DA B is defined as angle B; the LA ratio is defined as angle A/angle B. DA, daughter artery; LA ratio, lateral angle ratio; LA, diameter of DA A; LB, diameter of DA B.

• 

  Fig. 2 The image of an aneurysm is classified as a deviated neck type (Type D). The image illustrates the method of dimension measurements: neck width, depth (the longest diameter between the neck and dome), width (the maximum distance vertical to height) and maximum size (Dmax, the largest measurement in terms of maximum dome diameter or width). Aspect ratio (AR) is calculated as depth divided by neck width, depth-to-width ratio (DW) is calculated as depth divided by width, and the bottleneck factor (BF) is calculated as width divided by neck width.

• 

  Fig. 3 The area under the receiver operating characteristic curve for the neck width is 0.566 (95% confidence interval, 0.490–0.642). The cut point for the neck width is 4.35 mm, the sensitivity is 67.4%, and the specificity is 40%.

• 

  Fig. 4 The area under the receiver operating characteristic curve for the aspect ratio is 0.781 (95% confidence interval, 0.719–0.844). The cut point for the aspect ratio is 1.18, the sensitivity is 70.5%, and the specificity is 74.4%.

• 

  Fig. 5 The area under the receiver operating characteristic curve for the lateral angle ratio is 0.622 (95% confidence interval, 0.543–0.711). The cut point for the lateral angle ratio is 1.50, the sensitivity is 73.6%, and the specificity is 48.9%.

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