Supplementary Material for: Geometric versus hemodynamic indexes for rupture-destined aneurysms: a retrospective cohort and a repeated-measures study

Introduction: A proper stratification of intracranial aneurysms is critical in identifying rupture-destined aneurysms and unruptured intracranial aneurysms. We aimed to determine the utility of geometric and hemodynamic indexes in differentiating two types of aneurysms, and to examine the characteristics of natural evolutionary changes of unruptured aneurysms. Methods: Rupture-destined aneurysm refers to an aneurysm that undergoes subsequent aneurysmal subarachnoid hemorrhage (SAH). On the other hand, an unruptured intracranial aneurysm is characterized by an aneurysm that does not experience rupture during serial time-of-flight magnetic resonance angiography (TOF-MRA). In addition to geometric indexes, signal intensity gradient (SIG), an in-vivo approximated wall shear stress from TOF-MRA, was measured in aneurysms. The difference between the maximum and minimum values of SIG in an aneurysm compared to parent arterial values was designated as the delta-SIG ratio. Results: This study analyzed 20 rupture-destined aneurysms in 20 patients and 45 unruptured intracranial aneurysms in 41 patients with follow-up TOF-MRA. While geometric indexes did not show differences between the two groups, the delta-SIG ratio was higher in the rupture-destined aneurysms (1.5±0.6 vs. 1.1±0.3, P=0.032). The delta-SIG ratio showed a higher area under the receiver operating characteristics curve for SAH than the size ratio (0.72 [95% CI, 0.58–0.87] vs. 0.56 [95% CI, 0.41–0.72], P=0.033). The longitudinal re-examination of TOF-MRA in the unruptured intracranial aneurysms revealed evidence of aneurysmal growth, while concurrently exhibiting hemodynamic stability. Discussion/Conclusion: The delta-SIG ratio showed higher discriminatory results between the two groups compared to geometric indexes. Aneurysmal rupture risk should be assessed by considering both geometric and hemodynamic information. This study was registered on ClinicalTrials.gov (NCT05450939).

引言：对颅内动脉瘤进行合理分层，对鉴别破裂高危动脉瘤与未破裂颅内动脉瘤至关重要。本研究旨在明确几何指标与血流动力学指标在区分这两类动脉瘤中的应用价值，并探讨未破裂动脉瘤的自然演化特征。

方法：破裂高危动脉瘤指后续发生动脉瘤性蛛网膜下腔出血（subarachnoid hemorrhage, SAH）的动脉瘤；未破裂颅内动脉瘤则指在系列飞行时间磁共振血管造影（time-of-flight magnetic resonance angiography, TOF-MRA）随访中未发生破裂的动脉瘤。除几何指标外，本研究还测量了信号强度梯度（signal intensity gradient, SIG）——一种通过TOF-MRA近似获得的体内壁切应力——在动脉瘤中的数值。将动脉瘤内SIG的最大值与最小值之差与父动脉的对应值进行比较，所得差值即为delta-SIG比值。

结果：本研究共纳入20例患者的20枚破裂高危动脉瘤，以及41例患者的45枚未破裂颅内动脉瘤，所有受试者均接受了TOF-MRA随访。几何指标在两组间未表现出显著差异，但破裂高危动脉瘤的delta-SIG比值更高（1.5±0.6 vs. 1.1±0.3，P=0.032）。针对蛛网膜下腔出血的预测，delta-SIG比值的受试者工作特征曲线下面积高于尺寸比值（0.72 [95%CI, 0.58–0.87] vs. 0.56 [95%CI, 0.41–0.72]，P=0.033）。对未破裂颅内动脉瘤的TOF-MRA纵向随访结果显示，动脉瘤出现生长迹象，但血流动力学状态保持稳定。

讨论与结论：与几何指标相比，delta-SIG比值对两组动脉瘤的鉴别效能更优。动脉瘤破裂风险的评估应同时结合几何信息与血流动力学信息。本研究已在ClinicalTrials.gov注册（编号NCT05450939）。