Advanced MR diagnostic imaging in pediatric glial cell tumors: from morphological to pathophysiological evaluation

Full text: Introduction: The conventional MR imaging is important, and in most cases necessary imaging tool for studying the macroscopic structure, for localization and distribution of a glial brain tumor. It is an integral part of the optimal MR protocol, which further comprises a diffusion, perfusion techniques, techniques for the permeability and oxygenation assessment, as well as MR spectroscopy to the metabolism assessment. What you will learn: Glial brain tumors in children - incidence, histology, classification, diagnosis; Nature and principles of MR diffusion, perfusion, techniques for permeability and oxygenation assessment, MR spectroscopy; Contemporary techniques allowing to obtain not only MR morphological information but also to evaluate the tumor the pathophysiology: the cellular atypia, cellularity, tumor neovascularization, oxygen consumption, metabolism, status of the blood-brain barrier. This assessment determines the biological potential of the tumor, treatment options and prognosis. Discussion: The findings from conventional MR examinations, incl. administration of gadolinium contrast agents are associated with the degree of glioma and can be useful for their classification. Taking into account that from 20% to 45 % of the unenhanced supratentorial gliomas are malignant, some low-grade gliomas enhance (ganglioglioma, pilocytic astrocytoma, oligodendroglioma), 9% of malignant gliomas have no contrast enhancement, and in general, the contrast enhancement is not seen as a reliable indicator for the infiltration extent. The contemporary MR techniques improve the assessment of the pathophysiology of the tumor which is relevant to its histology and biological potential. Conclusion: Modern MR techniques besides purely diagnostic advantages (determine the extent and distribution of glioma), enable: differentiation of tumor recurrence from radiation necrosis; identification of optimal locations for biopsy or operative resection; prognosis, planning and following the effect of the treatment - determining the exact boundaries of the tumor, which are of great importance in the radiotherapy planning; development of new concepts and new therapeutic agents - anti-angiogenesis drugs and medications affecting tumor oxygenation