Elsevier

World Neurosurgery

Volume 114, June 2018, Pages e338-e343
World Neurosurgery

Original Article
Morphological Parameters Related to Aneurysm Wall Enhancement in Patients with Multiple Intracranial Aneurysms

https://doi.org/10.1016/j.wneu.2018.02.182Get rights and content

Highlights

  • The relationship between morphology and aneurysm wall enhancement was investigated.

  • Only patients with multiple unruptured aneurysms were included to balance the baseline features.

  • Morphological parameters were found to be highly associated with aneurysm wall enhancement.

  • Aneurysm size and irregular shape were independently related to aneurysm wall enhancement.

Background

Vessel wall magnetic resonance imaging (MRI) has been suggested as a potential in vivo method to detect inflammation of aneurysm wall and identify unruptured intracranial aneurysm (UIA) at high risk for rupture. This study aims to investigate the correlation between aneurysm wall enhancement (AWE) on vessel wall MRI and rupture-related morphological parameters in patients with multiple UIAs.

Methods

Clinical data and vessel wall MRI images were reviewed in 14 patients with 30 multiple UIAs. The AWE was defined as enhancement of the aneurysm wall in postcontrast vessel wall MRI using the precontrast MRI as a reference. Morphological parameters, including aneurysm size, aspect ratio, size ratio, bottleneck factor, height-to-width ratio, nonsphericity index (NSI), and inflow angle, were measured using 3-dimensional rotation angiography. Univariate and multivariate analyses were performed to evaluate the correlations between morphological parameters and the presence of AWE.

Results

Sixteen of the 30 multiple UIAs presented with AWE on vessel wall MRI. On univariate analyses, UIAs with AWE were significantly larger (P = 0.001) and had significantly higher aspect ratio (P = 0.047), size ratio (P = 0.003), bottleneck factor (P = 0.007), and NSI (P = 0.007) values. Further multivariate logistic regression showed that aneurysm size (odds ratio, 3.54; 95% confidence interval, 1.10–11.35; P = 0.033) and NSI (odds ratio, 3.53; 95% confidence interval, 1.06–11.80; P = 0.040) were independently associated with the presence of AWE in multiple UIAs.

Conclusions

The presence of AWE on vessel wall MRI was significantly correlated with conventional morphological rupture risk factors in patients with multiple UIAs, which might indicate AWE as a potential radiologic predictor for UIAs with high rupture risk.

Introduction

Because of the wide availability of advanced imaging techniques, unruptured intracranial aneurysms (UIAs) are common incidental findings, occurring in approximately 3% of the population.1, 2 The premise of reasonable decision making for treating UIAs is effective assessment of the risk of aneurysm rupture, which remains challenging, even though various attempts have been made.

Histopathological studies of animals and humans have indicated that inflammation plays a major role in aneurysm formation, growth, and rupture.3 The vessel wall magnetic resonance imaging (MRI) technique has developed into a capable noninvasive method for investigating aneurysm wall inflammation via aneurysm wall enhancement (AWE). The latter has been suggested to be highly related to aneurysm growth and rupture.4, 5, 6 Meanwhile, there is now increasing evidence suggesting that aneurysm morphology, including aneurysm shape, various size ratios, and flow angles, has a profound effect on aneurysm rupture and, given its simple and measurable nature, might be a feasible approach for predicting rupture in the clinical setting.7 However, the difference in aneurysm morphology between aneurysms with and without AWE, and how these 2 factors might interact to affect aneurysm rupture, requires further study.

Previous studies of aneurysm morphology have produced conflicting results. This may be due to the study design, in which the patients with ruptured aneurysms were compared with patients with unruptured aneurysms, differing in terms of such baseline characteristics as age, sex, and hypertension. In addition, the morphology of postruptured aneurysms might have changed dramatically, which is considered of little value in risk prediction.8 These confounding factors can be avoided by comparing the characteristics of UIAs of differing risk of rupture within the same patients. Therefore, in the present study, we compared morphological characteristics of aneurysms with or without AWE within the same patient with multiple UIAs to investigate the relationship between morphology and aneurysm wall characteristics.

Section snippets

Methods

The Institutional Review Board of Changhai Hospital approved this retrospective study and waived the requirement for informed consent. Patient information was anonymized and deidentified before analysis.

Results

The baseline and morphological characteristics of the 30 aneurysms in 14 patients (12 patients with 2 aneurysms and 2 patients with 3 aneurysms) are presented in Table 2. The patients ranged in age from 36 to 78 years, with a mean age of 57.7 years. Three patients were male, and 11 were female. Aneurysm size ranged from 2.5 mm to 15.9 mm, with a median size of 6.5 mm (interquartile range, 4.6–10.3 mm). The 30 aneurysms included 17 located in the internal carotid artery, 4 in the posterior

Discussion

In this study, we investigated the associations between morphological parameters and wall characteristics on vessel wall MRI in patients with multiple UIAs. The presence of AWE was highly associated with conventional risk factors for aneurysm rupture, especially aneurysm size and irregular shape. This finding may help expand our knowledge of the interaction of morphology and wall inflammation and its role in aneurysm rupture.

Depending on the completeness of the diagnostic procedures, multiple

Conclusions

The presence of AWE on vessel wall MRI was significantly correlated with conventional morphological rupture risk factors in multiple UIAs. Moreover, aneurysm size and irregular shape were independently associated with AWE. These results might suggest a relationship between AWE and aneurysm rupture and the potential use of AWE in clinical decision making for UIAs.

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    Conflict of interest statement: This work was supported by the National Research and Development Project of Key Chronic Diseases (Grant 2016YFC1300700) and National Natural Science Foundation of China (Grants 81571118, 81701775, and 81771264).

    Nan Lv and Haishuang Tang contributed equally to this work and should be considered co–first authors.

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