Comparisons between cross-section and long-axis-section in the quantification of aneurysmal wall enhancement of fusiform intracranial aneurysms in identifying aneurysmal symptoms

Abstract

Background: To investigate the quantification of aneurysmal wall enhancement (AWE) in fusiform intracranial aneurysms (FIAs) and to compare AWE parameters based on different sections of FIAs in identifying aneurysm symptoms.

Methods: Consecutive patients were prospectively recruited from February 2017 to November 2019. Aneurysm-related symptoms were defined as sentinel headache and oculomotor nerve palsy. All patients underwent high resolution magnetic resonance imaging (HR-MRI) protocol, including both pre and post-contrast imaging. CR_stalk (signal intensity of FIAs' wall divided by pituitary infundibulum) was evaluated both in the cross-section (CR_stalk-cross) and the long-axis section (CR_stalk-long) of FIAs. Aneurysm characteristics include the maximal diameter of the cross-section (D _max), the maximal length of the long-axis section (L _max), location, type, and mural thrombus. The performance of parameters for differentiating symptomatic and asymptomatic FIAs was obtained and compared by a receiver operating characteristic (ROC) curve.

Results: Forty-three FIAs were found in 43 patients. Eighteen (41.9%) patients who presented with aneurysmal symptoms were classified in the symptomatic group. In univariate analysis, male sex (P = 0.133), age (P = 0.013), FIAs type (P = 0.167), mural thrombus (P = 0.130), L _max (P = 0.066), CR_stalk-cross (P = 0.027), and CR_stalk-long (P = 0.055) tended to be associated with aneurysmal symptoms. In the cross-section model of multivariate analysis, male (P = 0.038), age (P = 0.018), and CR_stalk-cross (P = 0.048) were independently associated with aneurysmal symptoms. In the long-axis section model of multivariate analysis, male (P = 0.040), age (P = 0.010), CR_stalk-long (P = 0.046), and L _max (P = 0.019) were independently associated with aneurysmal symptoms. In the combination model of multivariate analysis, male (P = 0.027), age (P = 0.011), CR_stalk-cross (P = 0.030), and L _max (P = 0.020) were independently associated with aneurysmal symptoms. CR_stalk-cross has the highest accuracy in predicting aneurysmal symptoms (AUC = 0.701). The combination of CR_stalk-cross and L _max exhibited the highest performance in discriminating symptomatic from asymptomatic FIAs (AUC = 0.780).

Conclusion: Aneurysmal wall enhancement is associated with symptomatic FIAs. CR_stalk-cross and L _max were independent risk factors for aneurysmal symptoms. The combination of these two factors may improve the predictive performance of aneurysmal symptoms and may also help to stratify the instability of FIAs in future studies.

Keywords: MRI; aneurysm wall enhancement; fusiform aneurysm; quantification; symptom.

Figure 1

Three types of FIAs: fusiform (A), dolichoectatic (B), and transitional (C). Time-of-flight MR images (left column), post-contrast high-resolution MR images in the long-axis of the FIAs (middle column), and post-contrast high-resolution MR images in the cross-section of the FIAs (right column) are illustrated by each IFA (star).

Figure 2

Flowchart of patients' selection.

Figure 3

ROC curves of the contrast ratio of CR_{stalk−cross}, L_max, and the joint variable (CR_{stalk−cross} + L_max). The AUC value of CR_{stalk−cross}, L_max, and CR_{stalk−cross} + L_max were 0.701, 0.666, and 0.780, respectively. CR_{stalk−cross}, aneurysm-to-pituitary stalk in the cross-axis section; L_max, the maximal length of the long-axis section.