Quantitative Lesion Water Uptake in Acute Stroke Computed Tomography Is a Predictor of Malignant Infarction

Abstract

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.

Patients with low Alberta Stroke Program Early CT Score (ASPECTS) but good collaterals benefit from endovascular recanalization

“…While quantification of ischemic edema in multimodal CT in the setting of acute patient triage is technically not yet feasible and time-consuming, collateral scoring is fast and straight forward; it could therefore serve as selection criterion for different treatment options in low ASPECTS patients such as endovascular treatment with or without adjuvant anti-edematous medication to limit malignant edema 22 27 28. Our findings affirm the lately observed effect of vessel recanalization on lesion pathophysiology with reduced edema progression, which was directly associated with the observed effect on clinical endpoints 29–31.…”

“…First, it may stop penumbral loss and further infarct growth, which may be significant even in low ASPECTS patients 18. Second, it may prevent malignant edema by counteracting the disbalance of water homeostasis with lower levels of lesion water uptake, as suggested by our data 22…”

“…shows an example of two low ASPECTS patients with good versus poor collaterals. We determined net water uptake (NWU) within early infarct as the imaging biomarker to quantify cerebral ischemic edema in the admission CT before treatment and in FCT after treatment with a standardized procedure, as reported elsewhere 19–22…”

“…A sub-analysis was performed using volumetrically derived ischemic core volumes from cerebral blood volume maps, as reported elsewhere 19 22. Ischemic core volume was analyzed in a multivariable logistic regression model including collateral scores, recanalization status, and age.…”

CT‐Based Classification of Acute Cerebral Edema: Association with Intracranial Pressure and Outcome

“…39 On the other hand, CT signs of brain swelling without concomitant parenchymal hypoattenuation in patients with acute cerebral ischemia may suggest ischemic penumbral or oligemic tissue as evaluated by diffusion and perfusion studies. 40 Methods to differentiate between infarct volume and perilesional edema using CT include identifying net water uptake 41,42 and dual-energy CT. 43 In our study, perilesional edema was differentiated from ischemic areas by comparing MRI diffusion weighted imaging with CT as has been demonstrated before. 44,45 As penumbra cannot be differentiated from edema beyond doubt, 44,45 it was considered a part of the edema.…”