The importance of magnetic resonance tomography in the diagnosis of cerebral infections

Amongst 1.345 MR examinations of the skull 49 patients were suspected of a cerebral infection. With a knowledge of the clinical situation, the abnormal findings were classified according to their localization, number, extent and distribution. The final diagnoses included meningitis, meningoencephalitis, and abscesses of varying etiology. CT was carried out in 29 patients; it was found that MRI was more sensitive and able to show the lesion at an earlier stage (sensitivity 90% compared with 66%). Observations of proton density and relaxation time combined with morphological criteria and clinical history reduced differential diagnoses. On the other hand, the changes due to intracranial infections lead to an inflammatory reaction that may be similar to the findings in degenerative or even tumorous cerebral lesions. This explains why twelve patients with abnormal MRI findings were erroneously diagnosed as having cerebral infections.