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Space-occupying lesions of the spinal cord and lower medulla oblongata still represent a clinical and diagnostic challenge to the neurosurgeon, and up until very recently a preoperative diagnosis of the tumor’s nature was impossible. This was because the conventional diagnostic neuro-radiological procedures such as myelography and computed tomography (CT) often fail to establish a diagnosis in the “problem” zones of the neu-raxis. These are areas with very close anatomical relations to surrounding bony structures, e.g., the temporobasal structures, the posterior fossa, and in particular the spinal cord. It is in these areas that the technique of magnetic resonance tomography (MRT) has revolutionized the neuroradiological workup and has been particularly helpful in diagnosing syringes and spinal cord tumors of various nature.

Significant progress in diagnosis of intracranial tumors has been made during the past decade. In the late 1970s, computed tomography (CT) became an established technique in neuroimaging, which had proven its diagnostic potential especially in regard to intracranial tumors [5]. In the early 1980s, magnetic resonance (MR) imaging was introduced into clinical practice [1]. Although MR is widely used nowadays and advances have been tremendous, a lot of difficulties still remain in interpreting MR data [1]. The correlation between histological diagnoses and tissue dignity on the one hand and ϱ, T1, and T2 parameters on the other hand is one area in which knowledge is limited [3, 4]: first results seem to be less promising than was hoped for at the beginning of the MR period [3, 4]. For these reasons, we reviewed some of our meningioma cases that were studied with MR and compared the very variable histological pattern of these tumors with their heterogeneous MR characteristics.

Soon after the introduction of computed tomography (CT), numerous reports documented its usefulness in detection of cerebral abnormalities in epileptic disease (e.g., 2, 3, 8, 10, 14). The total number of abnormal findings varies considerably (7, 17, 22). Magnetic resonance (MR) imaging is superior to CT in detecting cerebral demyelination, rivals CT in imaging of brain tumors, and has tremendous potential in evaluating structural disease of the central nervous system (5, 11, 21). Therefore, we investigated the value of MR in the examination of epileptic disease when CT has been normal.

During the past three years 27 patients with medullary and/or brainstem cavities were examined with MRI at the Institute of Roentgenology, and we report the radiological MRI correlative findings. Five patients were operated: postoperative MRI examinations were compared with preoperative studies.

The first images using magnetic resonance (MR) were realized in 1973 (12). Clinically useful MR scans of the head were published at the beginning of the current decade (9, 11, 16), and imaging quality has now attained high standards (3). At present the expensive MR technique is not only used in a research and university setting, but in private clinical practice too (2).

Two cases of colloid cyst of the third ventricle are reported. Their computed tomographic (CT), magnetic resonance (MR) and neuropathological features are presented. The MR findings were different in the two cases for reasons not yet fully explained, full biochemical and biophysical analyses of the cyst contents not being available. Neuropathologically, the only significant difference was the abundant presence of cholesterin crystals in the colloid of case 1 and their absence in case 2. One of our cases is also peculiar from a CT point of view, since it was primarily hypodense and did not enhance on intravenous contrast administration.