Threshold values of morphological parameters associated with cerebral aneurysm rupture risk

Numerous studies have shown that morphological parameters of aneurysms are associated with their rupture. However, literature data on the values of these parameters vary significantly. The objective of this study is to identify image-based morphological parameter values which correlate with cerebral aneurysm rupture and can be used during preoperative planning to detect aneurysms prone to rupture. Mean values of the morphological factors such as aspect ratio and size ratio were chosen from the literature. These factors were sampled for ruptured and unruptured aneurysms. Statistical analysis of these factors was performed. Statistically significant differences were obtained between mean values in samples of size ratio and aspect ratio for ruptured and unruptured aneurysms. There were no statistically confirmed differences between size ratios for ruptured and unruptured anterior communicating artery aneurysms. In contrast, such differences were revealed for both of examined parameters for posterior communicating artery and middle cerebral artery. ROC analysis revealed critical values of aspect ratio and size ratio which distinguish ruptured aneurysms from unruptured ones. High correlation was obtained between size ratio and aspect ratio. Mean values of aspect ratio and size ratio published in recent articles are smaller than the values published 10–15 years ago. Diagram size ratio — aspect ratio showed threshold value of aspect ratio. It was shown that among considered morphological factors, aspect ratio was meaningful. Moreover, aspect ratio correlates with size ratio, and therefore we assume that size ratio is redundant. The obtained criterion value of AR $= 1.2$ in our opinion is logical. It was also confirmed by ROC analysis.