The Reliability of Measuring Early Brain Edema with Computed Tomography

Background: Postoperative brain edema is a common complication in patients with high-grade glioma after craniotomy. Both Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) are applied to diagnose brain edema. Usually, MRI is considered to be better than CT for identifying brain edema. However, MRI is not generally applied in diagnosing acute cerebral edema in the early postoperative stage. Whether CT is reliable in detecting postoperative brain edema in the early stage is unknown. Objective: This study aimed at investigating the agreement and correlation between CT and MRI for measuring early postoperative brain edema. Methods: Patients with high-grade glioma who underwent craniotomy in the Beijing Tiantan hospital from January 2017 to October 2018 were retrospectively analyzed. The region of interest and operative cavity were manually outlined, and the volume of postoperative brain edema was measured on CT and MRI. Pearson correlation testing and the Intraclass Correlation Coefficient (ICC) were used to evaluate the association and agreement between CT and MRI for detecting the volume of postoperative brain edema. Results: Twenty patients were included in this study. The interrater agreement was perfect for detecting brain edema (CT: Κ=1, ICC=0.977, P<0.001; MRI: Κ=0.866, ICC=0.963, P<0.001). A significant positive correlation and excellent consistency between CT and MRI were found for measuring the volume of brain edema (rater 1: r=0.97, ICC=0.934, P<0.001; rater 2: r=0.97, ICC=0.957, P<0.001). Conclusion: Substantial comparability between CT and MRI is demonstrated for detecting postoperative brain edema. It is reliable to use CT for measuring brain edema volume in the early stage after surgery.