**Acknowledgements**

**Radiotracer Mechanism Advantages Disadvantages**

FET Artificial amino acid transported

198 Neurooncology - Newer Developments

FDOPA Fluorinated form of L-DOPA, the

FLT Thymidine analogue and substrate

thymidine kinase 2

Choline Water-soluble B-complex vitamin

phospholipids

FMISO First-generation nitroimidazole;

tension

Somatostatin analogues

enters cells by diffusion and subsequently reduced at a rate inversely proportional to oxygen

Bind with high affinity to somatostatin receptors expressed richly by neuroendocrine tumours and some non-neuroendocrine tumours including meningiomas

into glioma

precursor of dopamine that is transported physiologically into brain and abnormally (increased)

for cellular thymidine kinase 1 but poor substrate for mitochondrial

phosphorylated and subsequently integrated into lecithin, a component of cell membrane

into upregulated glioma cells but not incorporated into proteins

radiotherapy planning, and detection of tumour recurrence in PET

> Use in grading of gliomas requires dynamic analysis of activity over time since not incorporated into proteins

Limited data outside of use for initial diagnosis of glioma

May accumulate in benign brain lesions with disrupted blood–brain barrier

May accumulate in benign inflammatory lesions

Requires venous blood sampling for quantification

Requires venous blood sampling for quantification

Limited data for use in radiotherapy planning

of hypoxia

of hypoxia

Overall accuracy for diagnosis of glioma comparable to MET; can distinguish active tumour from radiation necrosis; late phase FET PET

may be useful for grading

Uptake correlates with tumour proliferation and grade; more accurate than FDG for evaluating low-grade tumours and distinguishing tumour recurrence from radiation necrosis

More sensitive than FDG for detection of recurrent high-grade glioma; correlates better with tumour progression and survival

Can be radiolabelled with C-11 and F-18; higher uptake generally corresponds with higher grade; more accurate than FDG for distinguishing tumour recurrence from radiation

Permits quantification of hypoxia which has been shown to predict worse prognosis; can differentiate low

Excellent tumour-to-background contrast for neuroendocrine tumours; appears promising for tumour delineation in radiotherapy planning

from high grade gliomas

meningiomas

necrosis

than FMISO

FAZA Second-generation nitroimidazole Better hypoxia-to-normoxia contrast

**Table 2.** Summary of radiotracers most commonly used in PET imaging of brain tumours.

W.P.L is supported by a Princess Alexandra Hospital Research Foundation grant.
