Spatiotemporal dynamics of computed tomography perfusion (CTP) parameters following aneurysmal subarachnoid hemorrhage (SAH)

Preclinical and clinical studies suggest an early and progressive deterioration in cerebral perfusion leading to delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (SAH). Computed Tomography Perfusion (CTP) has then been investigated for DCI diagnosis and prognosis. However, spatial and temporal evolution of CTP-derived metrics have not been established, such that optimal CTP periodicity for monitoring and metrics thresholds for triggering intervention remain unclear. We developed an image processing pipeline to quantify CTP parameters' dynamics in SAH patients. Sixty-two patients were retrospectively included. Cerebral vasospasm (CVS) occurrence was 68%, that of DCI 15%. CTP parameters displayed specific dynamics in each of the noCVS, <i>CVS</i>, and <i>DCI</i> groups. In the <i>DCI</i> category, <i>CBF</i> showed early hyperemia and global flow homogenization, followed by an increased mean and variability of <i>TMax</i>. These features were included in a DCI predictive model (AUC = 0.94 after bootstrapping correction). Two types of dynamics emerged in DCI patients, one characterized by high asymmetry between hemispheric parameters, the other by a rapid whole-brain deterioration of brain perfusion. In conclusion, CTP parameters' early dynamics allow to sort SAH patients that will develop either CVS or DCI, advocating for repeating CTP examinations to adapt therapeutic strategies.