Central nervous system disorders

II./4.4.: Diagnostic methods besides imaging

The demonstration of central nervous system tumours is performed with the help of a computed tomography (CT) scan with contrast material and/or magnetic resonance imaging (MRI). These diagnostic methods are being described elsewhere. Positron emission tomography (PET) helps to determine the grade of malignancy through assessing tumour metabolic activity. From the neurooncological point of view its most important role lays in the differentiation between malignant tumours and radionecrosis.

However, it is important to mention that not even the most modern technological methods are able to replace the histological diagnosis. If the surgical removal of the tumour can not be performed due to the localization of the tumour, or due to multiple tumours, or because of the age or neurological status of the patient then a CT- or MR-guided stereotactic biopsy is being performed. During the procedure the coordinates of the lesion are being defined under local anaesthesia with the help of a stereotactic frame secured to the scull, and then a biopsy is being performed. In our own sample morbidity was under 5%, and histological diagnosis was accurate in 96% of cases (9).