Positron emission tomography imaging in gliomas: applications in clinical diagnosis, for assessment of prognosis and of treatment effects, and for detection of recurrences.

Neuroimaging plays a significant role in the diagnosis of intracranial tumours, especially brain gliomas, and must consist of an assessment of location and extent of the tumour and of its biological activity. Therefore, morphological imaging modalities and functional, metabolic or molecular imaging modalities should be combined for primary diagnosis and for following the course and evaluating therapeutic effects. Magnetic resonance imaging (MRI) is the gold standard for providing detailed morphological information and can supply some additional insights into metabolism (MR spectroscopy) and perfusion (perfusion-weighted imaging) but still has limitations in identifying tumour grade, invasive growth into neighbouring tissue and treatment-induced changes, as well as recurrences. These insights can be obtained by various positron emission tomography (PET) modalities, including imaging of glucose metabolism, amino acid uptake and nucleoside uptake. Diagnostic accuracy can benefit from coregistration of PET results and MRI, combining high-resolution morphological images with biological information. These procedures are optimized by the newly developed combination of PET and MRI modalities, permitting the simultaneous assessment of morphological, functional, metabolic and molecular information on the human brain.