Elevated early lesion water uptake in acute stroke predicts poor outcome despite successful recanalization - When "tissue clock" and "time clock" are desynchronized.

Nawabi, Jawed; Flottmann, Fabian; Kemmling, Andre; Kniep, Helge; Leischner, Hannes; Sporns, Peter; Schön, Gerhard; Hanning, Uta; Thomalla, Götz; Fiehler, Jens; Broocks, Gabriel

BACKGROUND Ischemic water uptake in acute stroke is a reliable indicator of lesion age. Nevertheless, inter-individually varying edema progression has been observed and elevated water uptake has recently been described as predictor of malignant infarction. AIMS We hypothesized that early-elevated lesion water uptake indicates accelerated "tissue clock" desynchronized with "time clock" and therefore predicts poor clinical outcome despite successful recanalization. METHODS Acute middle cerebral artery stroke patients with multimodal admission-CT who received successful thrombectomy (TICI 2b/3) were analyzed. Net water uptake (NWU), a quantitative imaging biomarker of ischemic edema, was determined in admission-CT and tested as predictor of clinical outcome using modified Rankin Scale (mRS) after 90 days. A binary outcome was defined for mRS 0-4 and mRS 5-6. RESULTS Seventy-two patients were included. The mean NWU (SD) in patients with mRS 0-4 was lower compared to patients with mRS 5-6 (5.0% vs. 12.1%; p < 0.001) with similar time from symptom onset to imaging (2.6 h vs. 2.4 h; p = 0.7). Based on receiver operating curve analysis, NWU above 10% identified patients with very poor outcome with high discriminative power (AUC 0.85), followed by Alberta Stroke Program Early CT Score (ASPECTS) (AUC: 0.72) and National Institutes of Health Stroke Scale (NIHSS) (AUC: 0.72). CONCLUSIONS Quantitative NWU may serve as an indicator of "tissue clock" and pronounced early brain edema with elevated NWU might suggest a desynchronized "tissue clock" with real "time clock" and therefore predict futile recanalization with poor clinical outcome.