FET PET-CT is a scan that can detect brain tumours – both primary and metastatic. FET PET-CT is indicated in the use of imaging of brain metastases as follows
Detection of viable tumour tissue; Radiolabelled amino acid imaging is superior to FDG PET, CT and MRI for differentiation of viable tumour tissue from treatment induced non-malignant changes such as post-operative change, oedema or radiation necrosis. FET PET is also superior to FDG PET for low grade recurrence.
Tumour Delineation; superior for estimation of true tumour extension in both low and high-grade gliomas.
Selection of biopsy site; FET is recommended to guide stereotactic biopsy for classification and grading of glioma.
Non-Invasive tumour grading; FET PET may aid in differentiating high grade gliomas from histologically benign brain tumours or non-neoplastic lesions. Oligodendroglioma and oligo-astrocytoma could have greater uptake than high grade gliomas.
Therapy Planning; FET PET used in conjunction with anatomical imaging may better define tumour volumes for resection of radiation therapy.
Tumour response; FET PET may predict the response to chemo and radiation therapy as it allows for earlier detection of residual tumour post-surgery.
Radiolabelled amino acids offer improvement over anatomical imaging (CT/MRI) as well as FDG PET-CT due to the low uptake of amino acids in normal brain tissue and therefore may be more tumour specific as uptake is less impacted by inflammation (1,2)
1.EANM Procedure Guidelines for Brain Tumour Imaging using Radiolabelled Amino Acid Analogues, Vander Borght et al 2006
2.Impact of F18-Fluoro-ethyl-tyrosine PET Imaging on target definition for radiation therapy of high-grade glioma, Rosenschold et al, Neuro-Oncology, Vol 17, Issue 5, May 2015.