Time-to-maximum Analysis Using Rapid Processing of Perfusion and Diffusion Software for Assessment of the Risk of...

Perfusion computed tomography predicts and diagnoses delayed cerebral ischemia after subarachnoid hemorrhage, but challenges in precision and interpretation limit its adoption. This study investigated whether tissue time-to-maximum analysis during the peak term of cerebral vasospasm, processed via Rapid Processing of Perfusion and Diffusion, can stratify delayed cerebral ischemia risk in patients with subarachnoid hemorrhage.In this retrospective cohort study, patients with subarachnoid hemorrhage treated surgically or endovascularly from March 2021 to March 2025 at the Japanese Red Cross Kumamoto Hospital underwent perfusion computed tomography approximately 10 days after the onset. Time-to-maximum parameters were computed via Rapid Processing of Perfusion and Diffusion and analyzed using logistic regression to assess their association with subsequent delayed cerebral ischemia. The primary endpoint was the development of delayed cerebral ischemia.Of the 181 patients initially screened, 101 were included in the study. The cohort included 81 women, with a mean age of 65 years. Among the 101 patients, 22 developed delayed cerebral ischemia. Compared with those without delayed cerebral ischemia, the delayed cerebral ischemia group had higher preoperative World Federation of Neurosurgical Societies grades and a higher frequency of significant cerebral vasospasm. The volume of time-to-maximum > 4 sec showed the strongest independent association with delayed cerebral ischemia. Receiver operating characteristic analysis identified a threshold of 31 mL for time-to-maximum > 4 sec, yielding a sensitivity of 0.91 and a specificity of 0.96. In multivariable logistic regression adjusting for World Federation of Neurosurgical Societies grade and cerebral vasospasm, time-to-maximum > 4 sec was associated with delayed cerebral ischemia development.The incorporation of time-to-maximum analysis via Rapid Processing of Perfusion and Diffusion may standardize perfusion computed tomography interpretation and enable delayed cerebral ischemia risk assessment.