Shear Stiffness of 4 Common Intracranial Tumors Measured Using MR Elastography: Comparison with Intraoperative Consistency Grading

BACKGROUND AND PURPOSE: The stiffness of intracranial tumors affects the outcome of tumor removal. We evaluated the stiffness of 4 common intracranial tumors by using MR elastography and tested whether MR elastography had the potential to discriminate firm tumors preoperatively. MATERIALS AND METHODS: Thirty-four patients with meningiomas, pituitary adenomas, vestibular schwannomas, and gliomas scheduled for resection were recruited for MR elastography. On the elastogram, the mean and the maximum shear stiffnesses were measured by placing an ROI on the tumor. Blinded to the MR elastography findings, surgeons conducted qualitative intraoperative assessment of tumor consistency by using a 5-point scale. Histopathologic diagnosis was confirmed by using the resected specimens. The mean and maximum shear stiffnesses were compared with histopathologic subtypes, and the intraoperative tumor consistency was graded by the surgeons. RESULTS: The mean and maximum shear stiffnesses were the following: 1.9 0.8 kPa and 3.4 +/- 1.5 kPa for meningiomas, 1.2 +/- 0.3 kPa and 1.8 +/- 0.5 kPa for pituitary adenomas, 2.0 +/- 0.4 kPa and 2.7 +/- 0.8 kPa for vestibular schwannomas, and 1.5 +/- 0.2 kPa and 2.7 +/- 0.8 kPa for gliomas. The mean and maximum shear stiffnesses for meningiomas were higher than those of pituitary adenomas (P < .05). The mean and maximum shear stiffnesses were significantly correlated with the surgeon's qualitative assessment of tumor consistency (P < .05). The maximum shear stiffness for 5 firm tumors was higher than that of nonfirm tumors (P < .05). CONCLUSIONS: MR elastography could evaluate intracranial tumors on the basis of their physical property of shear stiffness. MR elastography may be useful in discriminating firm tumors preoperatively.