Table 5.

Additional differentiation techniques between meningiomas and metastatic dural lesions.

Method	Mechanism	Metastatic/Malignant Tumors	Meningiomas/Benign Tumors
Functional MRI	Provides additional detail to assist in differential diagnosis as standard MRI might be unable to differentiate between the two lesions	Additional detail	Additional detail
MR Spectroscopy	Detects a pattern of lipid and/or lactate signals specific to metastatic tumors Must be performed prior to embolization Restricted to very large metastases	Malignant brain tumors have lower NAA/Cho, NAA/Cho + Cr, NAA/Cr and higher lactate/lipid, lactate/Cr tumor ratios when compared to benign brain tumors	Meningiomas have a high alanin/Cr ratio
Cytologic study of CSF and serologic study	Assists in the differentiation between meningiomas and metastatic tumors	Unique cytomorphology varies according to the organ of origin Well-defined cell borders Abundant cytoplasm	Rare spread of cells into the cerebrospinal fluid
Dynamic perfusion MRI (DPRMI)	Demonstrates different perfusion-sensitive characteristics between dural metastases and meningiomas DPRMI provides additional information regarding the vascularity of a tumor that is not available with conventional MRI Maps the cerebral blood volume and calculates the relative cerebral blood volume (rCBV), which is the ratio between the CBV in the tumor and the CBV in the white matter	Dural metastatic lesions typically have a low rCBV	Meningiomas typically have a high rCBV