The radiological diagnosis of meningiomas, the impact of EMI scanning

Abstract

A review of the impact of computerized axial tomography on the radiological diagnosis of meningiomas is presented. Seventy-one intracranial and eight orbital cases have been examined by this new method using the 160 X 160 matrix. The diagnostic accuracy of the method is compared with established neuroradiological methods of examination (plain X rays, angiography, pneumography and isotope scanning). The new non-invasive method is undoubtedly the most accurate diagnostic tool yet available. It provided a specific diagnosis of meningioma in 77% of the intracranial cases without contrast enhancement and diagnosed the presence of tumour in a further 19% giving an overall tumour diagnosis of 96%. There were three false negatives (4%). After intravenous injection of contrast medium specific diagnosis of meningioma was made in a further six cases raising the specific diagnostic rate to 86%. Specific identification of intra-orbital meningiomas is more difficult though the presence of retro-orbital tumour was correctly diagnosed in all eight cases examined (100%). In none of our cases was a false positive diagnosis of tumour made. However, there are areas where a specific diagnosis of meningioma can only be made as part of a wider differential diagnosis. Apart from the orbit these include the suprasellar area, the cerebello-pontine angle, and the intraventricular regions. Occasionally also supratentorial gliomas or secondaries can simulate meningiomas.

The reliability of computer tomography for the diagnosis and differential diagnosis of meningiomas, gliomas, and brain metastases

“…I-Iowever, an over-all rate of 85~o correct diagnoses (Table 8) with regard to the main histological groups is eneouragingi Even if the figures are small, the results are in accordance with our general experience and also with the experience of others. Thus, Claveria et al 3 reported 86% correct CT diagnoses in their 71 meningiomas. In Series 2 the diagnostic accuracy was largely the same in all types of tumours, although it was slightly lower for other gliomas and higher for metastases.…”

Cystic meninigioma

“…Cushing and Eisenhardt, in their series of meningiomas, report that cysts were present in 4.2% of patients. 5 Claveria et al found six cysts out of 71 patients with meningiomas, 12 and Russell et al reported six intratumoral and three arachnoid cysts in 131 patients with meningiomas. 7 The incidence may vary from 1.6% to 10%.…”

MRI in the diagnosis of cystic meningiomas: Surgical implications

“…Cystic meningiomas are quite rare, accounting for between 2% and 4% of all intracranial meningiomas [3,4,11,17].…”