Diagnosing dural metastases: the value of 1H magnetic resonance spectroscopy.

The purpose of this study was to assess the value of MRI, MR spectroscopy (MRS) and intra-arterial angiography in the preoperative diagnosis of extra-axial dural-based masses. We prospectively studied 54 patients who underwent preoperative MRI, MRS and angiography. Histologically there were 50 meningiomas and four dural metastases. MRI and angiography did not allow reliable differentiation between meningiomas and metastases. MRS showed elevated choline/creatine ratios in both meningiomas and metastases, but there were prominent lipid signals in all metastases and a lactate peak in two. This spectroscopic pattern was not found in meningiomas. However, following embolisation, they showed similar spectra, due to ischaemia and necrosis. We therefore believe MRS to be valuable in differential diagnosis of dural metastases and meningiomas prior to embolisation.