Introduction: Automated CT Perfusion (CTP) technology offers the potential to distinguish irreversibly damaged tissue from “at-risk,” potentially salvageable tissue. Regional Cerebral Blood Flow (CBF) < 30% has been identified as a good predictor of infarct core on CTP. Randomized trials investigating mechanical thrombectomy for large artery occlusion (LAO) acute ischemic stroke (AIS) have excluded patients with large core infarcts. We investigated the relationship between infarct core, as predicted by CTP, compared to the gold standard of DWI MRI, after revascularization of a proximal, anterior circulation, LAO AIS.
Hypothesis: CBF < 30% overestimates core infarct size compared to DWI MRI in at least one-third of patients with occlusions of the internal carotid artery (ICA) or middle cerebral artery (MCA) M1 or M2 segments treated with endovascular therapy achieving thrombolysis in cerebral infarction (TICI) grade 2b or 3.
Methods: From a large healthcare system’s stroke network database, we conducted a retrospective analysis comparing infarct core (CBF < 30%; RAPID iSchemaView) and post-revascularization DWI MRI (ADC < 620cc; RAPID iSchemaView) in patients with ICA, M1, or M2 LAO AIS between November 2016 and June 2017 with TICI 2b or 3 reperfusion.
Results: Over an 8-month period, 25 cases were identified with pre-treatment CTP, post-intervention MRI, and TICI 2b/3 revascularization of an ICA, M1, or M2 occlusion. Mean age was 61.1 years old and median NIHSS was 16. Mean duration from last known well time to CTP and MRI was 4.2 and 27.1 hours, respectively. Sixteen patients were treated with IV TPA and endovascular intervention, while 9 underwent only endovascular intervention. Median time to revascularization was 5.6 hours. CTP overestimated infarct size compared to follow-up MRI in 9/25 (36%) cases by an average of 17.8cc. Pearson correlation coefficient between CTP core infarct size and MRI infarct size was non-significant (r = 0.17, p = 0.41).
Conclusions: Core infarct size may be overestimated by CTP in a substantial number of patients with revascularization of proximal, anterior circulation LAO AIS. Caution should be exercised when using core infarct estimation of CBF < 30% to exclude patients from endovascular therapy.