Correlation Among Hemodynamic and Morphological Metrics of Intracranial Aneurysms

There is increasing interest in assessing metrics of blood flow characteristics as prognostic indicators of rupture risk in intracranial aneurysms. Aneurysmal hemodynamics may be and has been quantified in the literature by numerous indices (about 18, to the best of our knowledge) each capturing some characteristic of flow. But are all these indices capturing unique characteristics of flow or are many of them redundant? And are they mainly proxies for basic morphological characteristics? Answering this question and identifying the indices that capture unique aspects of flow has practical implications to prospective studies designed to test the hemodynamics-rupture correlation. Lesser the number of indices, lesser will be the required sample sizes for sufficient statistical power. Alternatively, greater the number of indices, greater the likelihood that such studies will descend into an exercise in data mining. Further, understanding how these indices relate among themselves and to morphology can help us better reconcile findings from independent studies. The objectives of this study were to first document and categorize all reported indices in the literature and use a population of unruptured intracranial aneurysms to understand correlations among them and with morphological indices.