Admission CT perfusion is an independent predictor of hemorrhagic transformation in acute stroke with similar accuracy to DWI

Abstract

Background: The utility of admission CT perfusion (CTP) to that of diffusion-weighted imaging (DWI) as a predictor of hemorrhagic transformation (HT) in acute stroke was compared.

Methods: We analyzed the admission CTP and DWI scans of 96 consecutive stroke patients. HT was present in 22 patients (23%). Infarct core was manually segmented on the admission DWI. We determined the: (1) hypoperfused tissue volume in the ischemic hemisphere using a range of thresholds applied to multiple different CTP parameter maps, and (2) mean relative CTP (rCTP) voxel values within both the DWI-segmented lesions and the thresholded CTP parameter maps. Receiver operating characteristic area under curve (AUC) analysis and multivariate regression were used to evaluate the test characteristics of each set of volumes and mean rCTP parameter values as predictors of HT.

Results: The hypoperfused tissue volumes with either relative cerebral blood flow (rCBF) <0.48 (AUC = 0.73), or relative mean transit time (rMTT) >1.3 (AUC = 0.70), had similar accuracy to the DWI-segmented core volume (AUC = 0.68, p = 0.2 and p = 0.1, respectively) as predictors of HT. The mean rMTT voxel values within the rMTT >1.3 segmented lesion (AUC = 0.71) had similar accuracy to the mean rMTT voxel values (AUC = 0.65, p = 0.24) and mean rCBF voxel values (AUC = 0.64, p = 0.22) within the DWI-segmented lesion. The only independent predictors of HT were: (1) mean rMTT with rMTT >1.3, and (2) mechanical thrombectomy.

Conclusion: Admission CTP-based hypoperfused tissue volumes and thresholded mean voxel values are markers of HT in acute stroke, with similar accuracy to DWI. This could be of value when MRI cannot be obtained.

Fig. 1

An 81-year-old female presenting 6 h after the onset of left-sided weakness and right gaze preference; not a candidate for endovascular therapy: a 5-mm thick CTA source image shows poor tissue opacification of the right MCA territory, b CTA maximum intensity projection image shows proximal right MCA occlusion with poor collateralization, c DWI shows right MCA territory infarct core, d thresholded MTT lesion (rMTT >1.3), with 140 ml total volume, e CBV map shows relative hyperemia (increased blood volume) of the cortical right MCA territory, f CBF map show decreased flow of the right MCA territory, corresponding to the DWI lesion, g MTT map shows corresponding area of prolonged transit time in the right MCA territory, mean rMTT = 4.3, and h 24 h follow-up NCCT shows HT at the anterior right MCA territory.