Impact of endovascular recanalization on quantitative lesion water uptake in ischemic anterior circulation strokes

Abstract

Studies evaluating the effect of reperfusion on ischemic edema in acute stroke described conflicting results. Net water uptake (NWU) per brain volume is a new quantitative imaging biomarker of space-occupying ischemic edema, which can be measured in computed tomography (CT). We sought to investigate the effects of vessel recanalization on the formation of ischemic brain edema using quantitative NWU. In this multicenter observational study, acute ischemic stroke patients with a large vessel occlusion (LVO) in the anterior circulation were consecutively screened. Patients with vessel recanalization (thrombolysis in cerebral infarction (TICI) 2 b or 3) versus persistent vessel occlusion (no thrombectomy, TICI 0-1) were compared. Lesion-NWU was quantified in multimodal admission CT and follow-up CT (FCT), and ΔNWU was calculated as difference. Of 194 included patients, 150 had successful endovascular recanalization and 44 persistent LVO. In FCT after treatment, the mean (standard deviation) ΔNWU was 15.8% (5.7) in patients with persistent LVO and 9.8% (5.8) with vessel recanalization (p < 0.001). In multivariate regression analysis, vessel recanalization was independently associated with a lowered ΔNWU by 6.3% compared to LVO (95% confidence interval: 3.7-9.0, p < 0.001). Successful vessel recanalization was associated with a significantly reduced formation of ischemic brain edema. Quantitative NWU may be used to compare the treatment effects in acute stroke.

Keywords: Biomarker; brain edema; computed tomography; stroke; thrombectomy.

Figure 1.

Quantification of NWU. Quantification of NWU as recently published.^,, NWU is determined in admission computed tomography (CT) using CBV parameter maps as template for region of interest definition in the non-enhanced CT (upper images). NWU in follow-up CT is quantified in non-enhanced CT (lower images) and its difference to admission CT is calculated (ΔNWU). NWU: net water uptake; CBV: cerebral blood volume.

Figure 2.

Difference in ΔNWU between follow-up and admission imaging in patients with persistent LVO versus patients with vessel recanalization. Boxplots representing NWU for both patient groups at admission imaging (left side) and ΔNWU in follow-up imaging (difference in NWU in FCT—admission CT). NWU: net water uptake; CT: computed tomography; CI: confidence interval; LVO: large vessel occlusion; FCT: follow-up CT.

Figure 3.

Effect plot of recanalization on ΔNWU and age. Based on multivariate regression analysis, ΔNWU (y-axis) is displayed separately for patients with persistent LVO (upper red line) and vessel recanalization (lower blue line). Age is plotted on the x-axis. LVO: large vessel occlusion; NWU: net water uptake.

Figure 4.

Regression analysis showing the relationship of ΔNWU and mRS score after 90 days according to recanalization status. mRS after 90 days according to ΔNWU (x-axis) and recanalization status (persistent vessel occlusion on the left side and vessel recanalization on the right side). NWU: net water uptake; mRS: modified Rankin Scale.

Figure 5.

Flow chart with application of exclusion criteria. TICI: thrombolysis in cerebral infarction.