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Prior to starting any kind of cerebral imaging examination, the detailed personal, anamnestic and physical examinational data should be provided, since e.g. various brain tumors develop in certain ages characteristically. In case of a metastatic tumor, knowledge on the primary tumor is important, furthermore, to what kind of cerebral localisations do the symptoms refer.
Either CT or MRI examination is performed to demonstrate brain tumor, the following questions must be answered:
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a.) Regarding localisation: Where is it located? : intra- or extraaxial, (in which compartment is it), supra- or infratentorial, is the midline respected or crossed?
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b.) Does the tumor produce pressure effect or structural distorsion on the adjacent structures? Is a space occupying effect present?
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c.) On CT examination: what kind of tissue characteristic features can be detected? E.g. intratumoral calcification, fat deposition, cystic degeneration.
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d.) On MRI examination: should the T1, T2 weighted and DWI sequences be performed, which sequences allow us to conclude on tissue features.
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e.) Pattern and degree of contrast enhancement must be observed (diffuse, patchy, annular).
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f.) Is there an edema and if so what extent?
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g.) Solitary or multiple lesion is visible?
Judgment of intra- or extraaxial localisation is important since (in adulthood) at least ¾ of the intraaxial tumors is a metastasis or astrocytoma, whilst 4/5 of the extraaxial tumors is principally a meningeoma, and secondly a schwannoma. Certain morphological signs can guide us in the decision of intra- or extraaxial localisation:
In extraaxially located tumors the subarachnoideal, superficially located vessels are displaced from their original localisation, and they are more internally located. The subarachnoideal space itself is also widened, displaced. A cortical ribbon can be observed between the tumor mass and the white matter.
A small, liquor containing spatium (space) is visible between the dura and the tumor. Dural insertion, wide based dural enhancement („dural tail”: characteristic for meningeoma), bone destruction (metastasis) and reactive bony lesion can develop by the tumor.
Contrast enhancement of extraaxial tumors is usually strong, since no rule of blood-brain barrier unpermeability does refer to these kind of tumors.
The chapter structure
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