Department of Neurosurgery, Thomas Jefferson University Hospital, Philadelphia, Pennsylvania, USA.
University of Cincinnati College of Medicine, Cincinnati, Ohio, USA.
World Neurosurg. 2023 Jul;175:e64-e72. doi: 10.1016/j.wneu.2023.03.028. Epub 2023 Mar 11.
Aneurysm morphology has been correlated with rupture. Previous reports identified several morphologic indices that predict rupture status, but they measure only specific qualities of the morphology of an aneurysm in a semiquantitative fashion. Fractal analysis is a geometric technique whereby the overall complexity of a shape is quantified through the calculation of a fractal dimension (FD). By progressively altering the scale of measurement of a shape and determining the number of segments required to incorporate the entire shape, a noninteger value for the dimension of the shape is derived. We present a proof-of-concept study to calculate the FD of an aneurysm for a small cohort of patients with aneurysms in 2 specific locations to determine whether FD is associated with aneurysm rupture status.
Twenty-nine aneurysms of the posterior communicating and middle cerebral arteries were segmented from computed tomography angiograms in 29 patients. FD was calculated using a standard box-counting algorithm extended for use with three-dimensional shapes. Nonsphericity index and undulation index (UI) were used to validate the data against previously reported parameters associated with rupture status.
Nineteen ruptured and 10 unruptured aneurysms were analyzed. Through logistic regression analysis, lower FD was found to be significantly associated with rupture status (P = 0.035; odds ratio, 0.64; 95% confidence interval, 0.42-0.97 per FD increment of 0.05).
In this proof-of-concept study, we present a novel approach to quantify the geometric complexity of intracranial aneurysms through FD. These data suggest an association between FD and patient-specific aneurysm rupture status.
动脉瘤形态与破裂有关。先前的报告确定了几个形态学指标，可以预测破裂状态，但它们仅以半定量方式测量动脉瘤形态的特定质量。分形分析是一种几何技术，通过计算分形维数（FD）来量化形状的整体复杂性。通过逐步改变形状的测量尺度并确定包含整个形状所需的段数，可以得出形状维度的非整数值。我们进行了一项概念验证研究，计算了 2 个特定位置的 29 例患者的动脉瘤的 FD，以确定 FD 是否与动脉瘤破裂状态相关。
从 29 例患者的计算机断层血管造影中分割出 29 个后交通和大脑中动脉的动脉瘤。使用标准的盒子计数算法计算 FD，该算法扩展后可用于三维形状。非球形指数和波动指数（UI）用于验证与破裂状态相关的先前报道的参数。
分析了 19 个破裂和 10 个未破裂的动脉瘤。通过逻辑回归分析，发现较低的 FD 与破裂状态显著相关（P=0.035；优势比，0.64；95%置信区间，0.42-0.97，FD 每增加 0.05）。
在这项概念验证研究中，我们提出了一种通过 FD 量化颅内动脉瘤几何复杂性的新方法。这些数据表明 FD 与患者特定的动脉瘤破裂状态之间存在关联。
