Contribution of MRI to the diagnosis and post-therapeutic monitoring of brain stem tumours.

MRI has become indispensable to the positive diagnosis of brain stem tumours which develop preferentially in young people. The prognosis of these tumours, especially infiltrating gliomas, being relatively sombre, it is important to make a precise morphological diagnosis of the lesions (increase in size, signal abnormalities) which will help both neurosurgeons and radiotherapists. As regards post-therapeutic monitoring, MRI with gadolinium contrast injection is harmless and will make it possible to follow these patients regularly and to detect recurrences.