Metabolism and regional cerebral blood volume in autoimmune inflammatory demyelinating lesions mimicking malignant gliomas.

Dynamic susceptibility contrast (DSC) magnetic resonance imaging (MRI) and MR spectroscopy are thought to differentiate tumefactive autoimmune inflammatory demyelinating lesions from glial brain tumours. The aim of this work is to evaluate whether regional cerebral blood volume (rCBV), as well as choline (Cho), N-acetyl-aspartate (NAA) and myo-inositol (mIns) concentrations differ between tumefactive lesions and World Health Organization (WHO) grade II-III gliomas. Five patients with single autoimmune inflammatory demyelinating lesions and nine patients with WHO grade II and III gliomas were examined by DSC-MRI and by two-dimensional (2D) 1H MR spectroscopic imaging (1H-MRSI). rCBV values and metabolite concentrations were normalised to the respective values of the contralateral hemisphere. Normalised rCBV in the tumefactive lesions (mean 2.89, range 1.98-6.74) was in the some high level as in gliomas (mean 2.77, range 1.43-6.22). 1H-MRSI revealed increased normalised choline concentrations in five of six examinations of autoimmune lesions (mean 1.4, range 1.06-1.8) and in eight of nine gliomas (mean 1.35, range 0.92-1.73). Tumefactive autoimmune inflammatory demyelinating lesions not only have imaging appearance of gliomas but may also imitate marked increase of rCBV and Cho in WHO grade II-III gliomas.