Neurointervention.  2010 Feb;5(1):13-22.

Morphology of Cerebral Saccular Aneurysms Characterized by Neck Angle Measured in Cross Sectional Analysis

• Ryu CW
• Koh JS
• Kim EJ

Abstract

PURPOSE
The neck angle is the novel geometric index that quantifies the aneurismal neck on cross sectional images. We characterized the morphology of aneurysms by the neck angle measured in the cross-sectional analysis of three-dimensional rotational angiography (3DRA).
MATERIALS AND METHODS
A total of 62 patients with 69 sidewall aneurysms was included in the study. Cross sectional images were acquired in the perpendicular planes of the axis of parent arteries by use of 3DRA, and the degree of parent artery involvement by the aneurysm ostium defined as neck angle. The neck angles of the aneurysms were categorized into four groups as follows: narrow (< 75degrees), moderate (75-90degrees), wide (91-115degrees) and extremely wide (> 115degrees). The cross sectional morphology of aneurysms in each group was evaluated. We obtained geometric indices of the sidewall aneurysms on 3DRA, including the width to neck ratio, aspect ratio, bottleneck ratio, depth to diameter of parent ratio (D/Dpa); and height to diameter of the parent ratio (H/Dpa). We evaluated the relationship between the neck angle and additional determined geographic indices in each case (Pearson's correlation).
RESULTS
The neck angle was linearly related with the aneurysm-to-parent vessel size ratios (D/Dpa and H/Dpa) (p < 0.05). With increasing neck angle, the parent artery became deformed and indistinguishable from aneurismal ostium.
CONCLUSION
The neck angle is a geometric index that demonstrates the morphologic relationship between aneurysm and parent artery. The cross sectional images of intracranial aneurysms can provide important information for characterization of aneurysms.

Keyword

Intracranial aneurysm; Morphology; Three-dimensional rotational angiography

MeSH Terms

Aneurysm
Angiography
Arteries
Axis, Cervical Vertebra
Cross-Sectional Studies
Glycosaminoglycans
Humans
Intracranial Aneurysm
Neck
Parents
Glycosaminoglycans