Introduction: Vasospasm is a devastating complication of aneurysmal subarachnoid hemorrhage(aSAH) and often diagnosed clinically or evaluated via modalities like transcranial doppler(TCD), CT angiography(CTA), digital subtraction angiography(DSA), or electroencephalography (EEG). More recently, RAPIDAI with CT Perfusion scans have allowed for the determination of early ischemic tissue. Herein, the predictive value of RAPIDAI is compared to other modalities used to assess patients with vasospasm after aSAH.
Methods: A retrospective analysis of patients with an aSAH presenting to a large quaternary center from 7/2020-9-2022 was performed. All patients with a RAPIDAI scan were included. In the study institution, RAPIDAI is performed in the majority of aSAH patients when there is concern for vasospasm. Optimal cutoffs for RAPID T-max and cerebral blood flow(CBF) were determined by maximizing the AUC in a thresholding analysis. Multivariate models using T-max and CBF were constructed with and without clinical parameters to predict vasospasm. All analysis was performed on R. A machine learning model was utilized to predict accuracy, as well as compare accuracy of different variables.
Results: Of 139 aSAH patients who presented during the study period, 46 were found to have had a RAPIDAI image of which 37 had clinical vasospasm. The optimal T-max boundary for clinical vasospasm was 8 seconds(s)(AUC=0.54), EEG vasospasm was 3s(AUC=0.76), and DSA vasospasm was 5s(AUC=0.61). Together, CBF and T-max were predictive of CTA-based vasospasm in a flow-dependent fashion – with a higher reduction in CBF and greater T-max associated with a greater probability of vasospasm diagnosis. Using comparative multivariate modeling, RAPIDAI was found to increase clinical diagnosis of vasospasm by 46.3%(p < 0.001).
Conclusion : The present study found RAPIDAI in aSAH patients to be predictive of CTA-based vasospasm in a flow dependent fashion. Further studies are needed to define the utility of RAPIDAI in aSAH patients; however, it may augment currently available diagnostic modalities for vasospasm.
