Purpose: The aim of this study was to investigate to which degree the peritumoral brain edema in patients with meningiomas depends on aquaporin-4 (AQP4) expression, tumor grade, tumor volume, Ki-67 expression, and cell count.
Procedures: Thirty-three patients (25 women, 8 men; mean age 56.6 ± 16.0 years) with an intracranial meningioma underwent a standardized magnetic resonance (MR) examination prior to surgical resection. Edema indices (EIs) and tumor volumes were measured on the MR images. Tumor grade was classified according to the World Health Organization, and the proliferation index was estimated on Ki-67 antigen-stained specimens. Tumor cell count was evaluated. Eighteen specimens were stained for AQP4 expressioon.
Results: Significant intergroup differences between AQP4 expression grades and EIs were observed (P = 0.03), and a positive correlation was detected between EIs and AQP4 expression grades (r = 0.54; P < 0.05). A ROC analysis with EI as a test variable revealed an AUC of 0.77 (95 % CI 0.55-0.99) for the prediction of a moderate-to-strong AQP4 expression. An EI ≥1.5 predicted a moderate-to-high AQP4 expression with a sensitivity of 77 % and a specificity of 60 %. EI values of 2.2 and 3.5 reached sensitivity/specificity values of 69/80 % and 54/100 %, respectively. The AQP4 expression did not show any significant correlations with tumor grading, tumor volume, Ki-67 expression, or cell count. Moreover, we observed no significant positive or negative correlations between the EI and tumor grading (P = 0.7), tumor volume (P = 0.19), Ki-67 index (P = 0.9), and cell count (P = 0.34).
Conclusion: Peritumoral brain edema in patients with meningiomas may depend on AQP4 expression grades and not on tumor grade, tumor volume, Ki-67 expression, and cell count. The amount of edema predicted AQP4 expressions with moderate-to-good sensitivity and specificity.
Keywords: Aquaporin-4; Brain edema; Meningioma.