Automated computed tomography (CT) perfusion in the assessment of the ischaemic core in wake-up strokes: is it...

Wake-up strokes represent up to 27% of all acute strokes. The main objective of this study was to assess the reliability of computed tomography perfusion (CTP) in the assessment of the acute ischaemic core in this population.

Intracranial CT and CTP studies of 117 consecutive patients (55 female, mean age 75, range 32-90) presenting with wake-up strokes and large vessel occlusion on CT angiography were included. Studies were retrospectively reviewed by two neuroradiologists in consensus in a blinded manner to determine Alberta Stroke Programme Early CT Score (ASPECTS) score on the presenting CT and CTP (relative cerebral blood flow [rCBF] maps) studies, with follow-up CT acting as the reference standard.

Correlation between rCBF ASPECTS and follow-up CT ASPECTS (Pearson correlation coefficient 0.68) was less compared to plain CT ASPECTS and follow-up CT ASPECTS (Pearson correlation coefficient 0.85) (P < 0.05). There was concordance between CT ASPECTS and rCBF ASPECTS in 55 patients (47%). However, in 44 cases (38%), rCBF ASPECTS underestimated the ischaemic core compared to CT ASPECTS. Out of these 44 cases, in 26 cases (22%), the CTP was normal, with a rCBF ASPECTS score of 10, whilst CT showed clear acute but established ischaemic change.

This study shows that CTP alone is not reliable in the assessment of the ischaemic core in the wake-up stroke population. Both noncontrast CT and CTP need to be carefully assessed in conjunction when considering thrombectomy eligibility in this group as established ischaemic change may be underestimated by CTP in up to 38% of patients, likely due to the delayed presentation.