Knowledge of meningioma-brain adhesion can be important to surgical outcome but has been reliably assessed only during surgery. Slip interface imaging (SII), a recently developed MR-elastography based technique, is capable of determining the degree of meningioma-brain adhesion preoperatively. In SII, a non-adherent meningioma demonstrates a hyper-intense octahedral shear strain (OSS) contour along the tumor-brain interface. In 25 meningiomas, an algorithm improved by normalizing OSS to the combined wave amplitude provided a more accurate prediction in the setting of peritumoral edema. Normalized OSS increased SII accuracy from 72% to 92%, and the kappa coefficient increased from 0.37 (fair) to 0.86 (good).