Background

Morphological irregularity is linked to intracranial aneurysm wall instability and manifests in the lumen shape. Yet there is currently no consent on how to assess shape irregularity. The aims of this work are to quantify irregularity as perceived by clinicians, to break down irregularity into morphological attributes, and to relate these to clinically relevant factors such as rupture status, aneurysm location, and patient age or sex.

Methods

Thirteen clinicians and 26 laypersons assessed 134 aneurysm lumen segmentations in terms of overall perceived irregularity and five different morphological attributes (presence/absence of a rough surface, blebs, lobules, asymmetry, complex geometry of the parent vasculature). We examined rater agreement and compared the ratings with clinical factors by means of regression analysis or binary classification.

Results

Using rank-based aggregation, the irregularity ratings of clinicians and laypersons did not differ statistically. Perceived irregularity showed good agreement with curvature (coefficient of determination R² = 0.68 ± 0.08) and was modeled very accurately using the five morphological rating attributes plus shape elongation (R² = 0.95 ± 0.02). In agreement with previous studies, irregularity was associated with aneurysm rupture status (AUC = 0.81 ± 0.08); adding aneurysm location as an explanatory variable increased the AUC to 0.87 ± 0.09. Besides irregularity, perceived asymmetry, presence of blebs or lobules, aneurysm size, non-sphericity, and curvature were linked to rupture. No association was found between morphology and any of patient sex, age, and history of smoking or hypertension. Aneurysm size was linked to morphology.

Conclusions

Irregular lumen shape carries significant information on the aneurysm’s disease status. Irregularity constitutes a continuous parameter that shows a strong association with the rupture status. To improve the objectivity of morphological assessment, we suggest examining shape through six different morphological attributes, which can characterize irregularity accurately.

中文翻译：

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颅内动脉瘤腔的形状不规则具有诊断价值。

背景

形态不规则与颅内动脉瘤壁的不稳定性有关，并表现为管腔形状。然而，目前尚无关于如何评估形状不规则性的共识。这项工作的目的是量化临床医生认为的不规则性，将不规则性分解为形态学特征，并将其与临床相关因素（例如破裂状态，动脉瘤位置以及患者年龄或性别）相关联。

方法

13名临床医生和26名非专业人士对134个动脉瘤管腔分割进行了评估，包括整体感觉到的不规则性和五种不同的形态学特征（粗糙表面的存在/不存在，气泡，小叶，不对称，父脉管的复杂几何形状）。我们检查了评分者的一致性，并通过回归分析或二元分类将评分与临床因素进行了比较。

结果

使用基于等级的汇总，临床医生和非专业人员的违规等级在统计上没有差异。感知的不规则性表现出与曲率的良好一致性（确定系数R ²  = 0.68±0.08），并且使用五个形态学等级属性加形状伸长率（R ² = 0.95±0.02）。与以前的研究一致，不规则与动脉瘤破裂状态有关（AUC = 0.81±0.08）；增加动脉瘤位置作为解释变量将AUC增加到0.87±0.09。除不规则性外，还可以感知到不对称，气泡或小叶的存在，动脉瘤的大小，非球形性和曲率与破裂有关。形态与患者的性别，年龄，吸烟史或高血压史均无关联。动脉瘤的大小与形态有关。

结论

不规则的管腔形状携带有关动脉瘤疾病状态的重要信息。不规则性构成一个连续参数，显示出与破裂状态的强烈关联。为了提高形态学评估的客观性，我们建议通过六个不同的形态学属性检查形状，这些属性可以准确地表征不规则性。