Effective acute stroke treatment relies on precise ischaemic core estimation. Although CT perfusion (CTP) is widely used, its accuracy may be affected by tracer diffusion characteristics and the imaging timing relative to endovascular treatment (EVT). This research sought to determine optimal relative cerebral blood flow (rCBF) thresholds for accurate ischaemic core estimation via CTP, in comparison to both immediate and delayed diffusion-weighted imaging (DWI) outcomes, emphasizing the impact of the interval between perfusion imaging and recanalisation.
This retrospective analysis included 175 large vessel occlusion (LVO) stroke patients who underwent CTP prior to EVT and subsequent DWI at Seoul National University Bundang Hospital from January 2015 to May 2023. Ischaemic core volumes derived from CTP at various rCBF thresholds were validated against DWI volumes obtained within 3 hours and between 24 to 196 hours post-EVT. The study employed concordance correlation coefficients and Bland-Altman plots to evaluate the agreement at different rCBF thresholds.
Results indicated that the optimal rCBF threshold for immediate DWI was <22%, while for delayed DWI, it was <30%. Early recanalisation significantly influenced the overestimation of ischaemic core size at higher rCBF thresholds, underscoring the critical role of recanalisation timing in accurate core estimation.
These findings suggest that adjusting rCBF thresholds according to DWI timing post-EVT can improve the precision of ischaemic core assessment in acute stroke, potentially impacting treatment decisions.