Background and Purpose- Early selection of patients with acute
middle cerebral artery infarction at risk for malignant
edema is critical to initiate timely decompressive surgery. Net water uptake (NWU) per brain volume is a quantitative imaging
biomarker of space-occupying ischemic
edema which can be measured in computed tomography. We hypothesize that NWU in early
infarct lesions can predict development of malignant
edema. The aim was to compare NWU in acute
brain infarct against other common predictors of malignant
edema. Methods- After consecutive screening of single-center registry data, 153 patients with acute proximal
middle cerebral artery occlusion fulfilled the inclusion criteria. A total of 29 (18.2%) patients developed malignant
edema defined as end point in follow-up imaging leading to decompressive surgery and death as a direct implication of mass effect. Early
infarct lesion volume and NWU were quantified in multimodal admission computed tomography; time from symptom onset to admission imaging was recorded. Results- Mean time from onset to admission imaging was equivalent between patients with and without malignant
infarcts (mean±SD: 3.3±1.4 hours and 3.3±1.7 hours, respectively). Edematous
tissue expansion by NWU within
infarct lesions occurred across all patients in this cohort (NWU: 9.1%±6.8%; median, 7.9%; interquartile range, 8.8%; range, 0.1%-35.6%); 7.0% (±5.2) in nonmalignant and 18.0% (±5.7) in malignant
infarcts. Based on univariate receiver operating characteristic curve analysis, NWU >12.7% or an
edema rate >3.7% NWU/h identified malignant
infarcts with high discriminative power (area under curve, 0.93±0.02). In multivariate binary logistic regression, the probability of malignant
infarct was significantly associated with early
infarct volume and NWU. Conclusions- Computed tomography-based quantitative NWU in early
infarct lesions is an important
surrogate marker for developing malignant
edema. Besides volume of early
infarct, the measurements of lesion water uptake may further support identifying patients at risk for malignant
infarction.