[Radiological aspects of acoustic neurinoma].

For a long time CT constituted the technique of choice for the investigation and pretreatment staging of acoustic neuroma. It is sometimes inadequate especially for defining the extra-axial site of a tumour or for identifying small lesions. Today, any case of suspected acoustic neuroma should undergo first-line MR studies. MR identifies almost all extra-axial lesions, clearly visualises small lesions and provides a satisfactory pretreatment staging in the majority of cases, acoustic neuroma presents a signal intensity identical to or lower than that of the brainstem with a high intensity signal on T2-weighted SE sequences and post-gadolinium T1-weighted SE sequences, generally with a mixed intra- and extra-meatal location and eccentric in relation to the anterior border of the porus.