Role of hydrodynamic processes in the pathogenesis of peritumoral brain edema in meningiomas

Object. In a prospective study, 28 patients with 32 intracranial meningiomas were examined to determine the role of hydrodynamic interaction between tumor and surrounding brain tissue in the pathogenesis of peritumoral brain edema. Methods. Gadolinium-diethylenetriamine pentaacetic acid (Gd-DPTA), an extracellular contrast agent used for routine clinical imaging, remains strictly extracellular without crossing an intact blood-brain barrier. Therefore, it is well suited for investigations of hydrodynamic extracellular mechanisms in the development of brain edema. Spin-echo T-1-weighted magnetic resonance images were acquired before and after intravenous administration of 0.2 mmol/kg Gd-DPTA. Additional T-1-weighted imaging was performed 0.6, 3.5, and 6.5 hours later. No significant Gd-DPTA diffused from tumor into peritumoral brain tissue in 12 meningiomas without surrounding brain edema. In contrast, in 17 of 20 meningiomas with surrounding edema, contrast agent in peritumoral brain tissue was detectable after 3.5 hours and 6.5 hours. In three of 20 meningiomas with minimum surrounding edema (< 5 cm(3)), contrast agent effusion was absent. After 3.5 hours and 6.5 hours strong correlations of edema volume and the maximum distance of contrast spread from the tumor margin into adjacent brain parenchyma (r = 0.84 and r = 0.87, respectively, p < 0.0001) indicated faster effusion in larger areas of edema. Conclusions. The results of this study show that significant contrast agent effusion from the extracellular space of the tumor into the interstitium of the peritumoral brain tissue is only found in meningiomas with surrounding edema. This supports the hypothesis that hydrodynamic processes play an essential role in the pathogenesis of peritumoral brain edema in meningiomas.