1HMRS 3T in vivo and in vitro and anatomopathological correlations in extracerebral tumours. A report of two cases.

We describe two patients with extracerebral tumours histologically diagnosed as metastasis with focal necrosis (case 1) and a meningioma with microcystic features (case 2) examined by proton magnetic resonance spectroscopy. Tumour metabolism did not fit leterature report as lipids were not detected in the metastasis but were found in the meningioma whose in vitro spectrum also showed metabolic abnormalities. This discrepancy may be due to the technique adopted in case 1 and the small amount of tumour necrosis, but it is difficult to account for in case 2. Some explanations are offered but long term follow-up scans will establish whether the abnormal metabolic features indicative of a negative prognosis are confirmed by the patients evolution. The cases described do not necessarily call other literature reports into question, but warrant caution in establishing a diagnosis on the basis 1HMRS findings. Spectrum acquisition techniques need to be standardized and short TE measurements are more reliable than those made with long TE.