الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
The goal of surgical treatment is to remove as much tumor tissue as possible, while in the same time preserving the integrity of eloquent cortical areas and/or white matter tracts, and thus avoid postoperative neurological deficits. However, tumor infiltration of eloquent cortical areas and/or white matter tracts may preclude safe gross total resection. Consequently, knowledge of the relationship between tumor and eloquent cortical and white matter regions might be helpful for preoperatively determining the extent to which a brain tumor can be surgically removed, and also for guiding the actual surgical procedure.
Diffusion-tensor magnetic resonance imaging (DTI) and fiber tractography are new methods that can demonstrate the orientation and integrity of white matter fibers in vivo and is considered a powerful method for characterizing changes in tissue microstructure associated with different brain disorders.
Before MR tractography, there was no other means of demonstrating the white matter tracts or having a 3 dimensional appreciation of their relations. Diffusion tensor tractography is the only imaging modality capable of generating realistic 3D maps of WMT in vivo.
28 patients with different types of intra-axial brain tumors were studied. Most of the studied cases were different types of gliomas. Conventional contrast enhanced MRI followed by MR Diffusion Tensor Imaging were acquired in all of the studied population.
White matter tracts involvement by a tumor was categorized into four patterns on DT mapping and Tractography, these are: edema, displacement, infiltration and disruption. Quantitative analysis was also obtained by measuring the FA and ADC values of each affected tract, with comparison with the contra lateral homologous tracts in the unaffected hemisphere.
We classified the patients into two groups: low grade group: including gliomas of grade I and II and, high grade group: including gliomas of grade III & IV and metastasis.
There was a statistically significant difference between these groups as regard the effect of edema and disruption, with prevalence of edema and infiltration effect among the high grade group with P value <0.05.
There was no statistically significant difference between the two groups regarding the effect of displacement and infiltration.
We could also discriminate between diffuse and focal brain stem gliomas, and elucidate the different tumor effects upon different white matter brain stem tracts.
In conclusion, the effect of cerebral neoplasm on white matter pathways is much better evaluated with the aid of DTI than on conventional MRI. There can be one or more of four distinct patterns of white matter tracts alteration by a tumor. In this small cohort of patients the information provided by DT imaging further defined precise relationships between the sub cortical white matter structures and the cerebral neoplasm. This potentially has a role in tumor characterization, and more importantly in surgical planning. MR Tractography offers the neurosurgeon an anatomical panoramic view and the opportunity for improved planning of surgical resection of intracranial lesions and in predicting the extent of safe resection.
Despite its limitations and potential pitfalls, DTI has proven to be the only clinically feasible method of demonstrating the white matter tracts in vivo.
This new technique should be considered an important step forward in modern neuro-radiological diagnostics for surgical planning of cerebral neoplasm.