الفهرس 
AstrocytomasOnly 14 pages are availabe for public view
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Abstract
A total of 53 cases of brain gliomas were studied in this series, 35 males and 18 females, aged
8-80 years to demonstrate the value of MRI as a diagnostic tool for intracranial
tumor as well as to throw light on the various capabilities of MRI to discriminate between
different types of brain gliomas by correlating the locations, shape, signal characteristics and
pattern of contrast enhancement.
Ail our cases were subjected to examination by MRl before and after IV injection of
GD-DTPA, and the collected data were analyzed (site, signal intensity, heterogeneity, border
definition, pattern of enhancement, presence of hemorrhage, edema and mass effect). The MRl
diagnosis was correlated in most of the cases with the pathology results.
The diagnosis of these cases were :
39 Fibrillary astrocytomas.
2 Pilocytic astrocytomas.
7 Brain stem gliomas.
I Subependymal giant cell astorcytoma.
1 Oligodendroglioma.
3 Ependymomas.
The findings at MR imaging in a group of 3 7 patholo gically verified fibrillary
astrocytomas were ana yzed and compared with the biopsy diagnosis to determine whether MR
imaging could be used to classify astrocytic series tumors into three tired system of
low grade astrocytoma, anaplastic
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astrocytoma, and GBM, and to evaluate MR imaging features that may aid in this classification.
The MR characteristics evaluated were tumor signal heterogeneity, border definition, edema, mass
effect, hemorrhage and contrast enhancement. Correct grading was reached in 28 out of 37
cases.
In the cases of diffuse or fibrillary astrocytomas we assume that the extent of edema,
intratumoral signal heterogeneity, marked heterogenous Gd-DTPA enhancement and mass effect
are more closely associated with increasing tumor grade. Tumor heterogeneity is demonstrated
best on T2WI. marked heterogenous Gd-DTPA enhancement was present in all high grade glioma
(grade 3 and 4) with the exception of one case of grade III astrocytoma.
Hemorrhage has been found in gliomas of all grades, however it is more likely to occur in high
grade tumors. The presence of hypointensity (hemosiderin) on T2 and PD images was though to
produce the largest difference between anaplastic astrocytoma and GBMs.
The high resolution of image quality produced by MRI in addition to the multiplanar capability
and absence of bony artifacts are needed in evaluating posterior fossa tumors. Sagittal
images are extremely helpful in evaluating midline lesions such as brain stem tumors,
ependymomas and vermian masses.
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MR also gives better appreciation as regard relation of the lesion to the surrounding structures
and extent of tumor infiltration.
Contrast enhancement was an important factor in MR studies and helped in the estimation of tumor
margin, size, multiplicity of lesion and detection of extension to the surrounding structures.
Spin echo MR imaging IS relatively insensitive to calcification, also precise separation of
the zone invaded by tumor from surrounding edema remain a drawback.
MR confirm the diagnosis of an intracranial mass lesion, in addition it provide information
regarding the location, size, extension and appearance of the mass. Based on this information an
initial estimation regarding therapy, specifically the feasibility of surgical resection or the
need for biopsy can be made.