Perfusion MR imaging for differentiation of benign and malignant meningiomas

Abstract

Introduction: Our purpose was to determine whether perfusion MR imaging can be used to differentiate benign and malignant meningiomas on the basis of the differences in perfusion of tumor parenchyma and/or peritumoral edema.

Methods: A total of 33 patients with preoperative meningiomas (25 benign and 8 malignant) underwent conventional and dynamic susceptibility contrast perfusion MR imaging. Maximal relative cerebral blood volume (rCBV) and the corresponding relative mean time to enhance (rMTE) (relative to the contralateral normal white matter) in both tumor parenchyma and peritumoral edema were measured. The independent samples t-test was used to determine whether there was a statistically significant difference in the mean rCBV and rMTE ratios between benign and malignant meningiomas.

Results: The mean maximal rCBV values of benign and malignant meningiomas were 7.16+/-4.08 (mean+/-SD) and 5.89+/-3.86, respectively, in the parenchyma, and 1.05+/-0.96 and 3.82+/-1.39, respectively, in the peritumoral edema. The mean rMTE values were 1.16+/-0.24 and 1.30+/-0.32, respectively, in the parenchyma, and 0.91+/-0.25 and 1.24+/-0.35, respectively, in the peritumoral edema. The differences in rCBV and rMTE values between benign and malignant meningiomas were not statistically significant (P>0.05) in the parenchyma, but both were statistically significant (P<0.05) in the peritumoral edema.

Conclusion: Perfusion MR imaging can provide useful information on meningioma vascularity which is not available from conventional MRI. Measurement of maximal rCBV and corresponding rMTE values in the peritumoral edema is useful in the preoperative differentiation between benign and malignant meningiomas.

Fig. 1

Histopathologically confirmed benign meningioma (WHO grade I). a–c MR images. T1-weighted (a), FLAIR (b) and contrast-enhanced T1-weighted (c) images show an inhomogeneous mass lesion on the right convexity with little peritumoral edema and heterogeneous enhancement. d rCBV map. The “hot” colors (red) of ROI 1 in the tumor parenchyma indicates a higher rCBV than the normal white matter (ROI 3, blue); the black color of ROI 2 in peritumoral edema indicates a lower rCBV than the normal white matter. The reference color scale is on the right side of the map. e rMTE map. The colors of the tumor parenchyma and peritumoral edema are similar to that of normal brain tissues; no clear interface can be seen

Fig. 2

Histopathologically confirmed malignant meningioma (WHO grade III). a–c MR images. T1-weighted (a), FLAIR (b) and contrast-enhanced T1-weighted (c) images show a mass with nearly isointense parenchyma accompanied by widespread peritumoral brain edema and strong homogeneous enhancement. d rCBV map. The red color of ROI 1 in the tumor parenchyma indicates a higher rCBV than the surrounding brain tissues; the green and blue colors of ROI 2 in the peritumoral edema are also “hotter” than ROI 3 (dark) in the normal white matter. The reference color scale is on the right side of the map. e MTE map. Most of the tumor parenchyma shows slightly “hotter” colors than the normal brain tissue, reflecting a prolonged rMTE