Proceedings of the British Institute of Radiology

Dexamethasone is a steroid routinely used in the treatment of brain tumours and is widely believed to improve symptoms, often within the space of a few hours, by diminishing peritumoural oedema. However, no significant brain water changes have been shown to occur within even 6 days of administration. In an attempt to elucidate the mechanism for such rapid amelioration in vivo  1H MRS has been utilized.