Morphological Characteristics of Ruptured Brain Aneurysms: A Systematic Literature Review and Meta-Analysis

Area of Science:

• Neurosurgery
• Radiology
• Biomedical Engineering

Background:

• Morphological features of brain aneurysms are not well-understood for predicting rupture risk.
• This meta-analysis aimed to identify key morphological determinants of aneurysm rupture status.

Purpose of the Study:

• To determine which morphological features of brain aneurysms are most predictive of rupture.
• To analyze aneurysm size, aspect ratio (AR), size ratio (SR), ellipticity index, nonsphericity index, and undulation index in relation to rupture status.

Main Methods:

• A meta-analysis was conducted using data from the Nested Knowledge platform.
• Included studies reported on various morphological features of ruptured and unruptured brain aneurysms.
• Effect sizes were calculated using mean differences between ruptured and unruptured aneurysm groups.

Main Results:

• 63 studies with 13,025 aneurysms (6966 ruptured, 6059 unruptured) were analyzed.
• Ruptured aneurysms were larger and had higher AR, SR, ellipticity, and nonsphericity indices compared to unruptured ones.
• Mean size of ruptured aneurysms was 6.1 mm; mean AR was 1.5; mean SR was 2.3.

Conclusions:

• Aneurysm size did not significantly differ between ruptured and unruptured cases in the anterior cerebral artery, anterior communicating artery, and basilar artery.
• Size ratio (SR) was significantly different across all locations.
• A mean AR of 1.5 and SR of 2.3 are identified as thresholds associated with ruptured aneurysm status.