الفهرس 
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Abstract
Gliomas are malignant neoplasms of glial cell origin. They account for 30-40% of all primary intra-cranial tumors. The peak age incidence is the middle adult life. In 2002, there were an estimated 17000 new cases of primary CNS tumor, most with WHO grades III or IV. Glioblastoma is a major health burden with poor outcome for most patients. It accounts for the second cancer-related deaths in adult males aged 20-39 years. This extremely poor prognosis has not changed despite 30 years of research, technological progress and clinical trials.
The Joint Section on Tumors of the American Association of Neurological Surgeons and Congress of Neurological Surgeons has provided practice guidelines, with the only firm recommendation being that biopsy is the standard of practice for the definite diagnosis and grading of CNS tumors, whether observation or further treatment is recommended.
However, there are some drawbacks for the sole dependence upon biopsy for definitive diagnosis and grading upon which the clinical decision is made. Glioblastoma is a highly heterogeneous tumor and in one tumor, all grades can be seen. This fact denotes that sampling errors are likely to occur, with consequent under-grading of the tumor and poor decision. Another important drawback is the occurrence of the tumor in high risk regions, e.g. brain stem, where biopsy is relatively contra-indicated and the need for non-invasive methods to give accurate and reliable diagnosis and grading are highly needed.
Our study had some limitations. Most important was the lack of biopsy from these invasive edges and targeted biopsy from the regions selected for pre-operative grading. Correlation with histopathology would have added greater value to our findings. We also didn’t look at some of the tumor-derived biomarkers, e.g. MGMT methylation status and IDH-1mutations; both factors are good prognostic factors.
We recommend performing more studies on a larger scale of patients with the inclusion of targeted biopsy and assessment of other tumor bio-markers before confirming this potential role for DTI to detect occult tumor extension.