PO2818F- FLUOROMETHYLCHOLINE (18F-FMC) PET/CT AND MAGNETIC RESONANCE SPECTROSCOPY (MRS) IMAGING AND TISSUE BIOMARKERS OF CELL MEMBRANE TURNOVER IN PRIMARY BRAIN GLIOMAS- A PILOT STUDY.

INTRODUCTION: Standard contrast enhanced MRI is not reliable for characterising glioma. Choline is a key component of cell membranes; its levels are increased in primary brain tumours, indicating how rapidly tumour cells are dividing. Imaging with 18F-FMC PET and MRS allow choline to be assessed non-invasively, although these imaging biomarkers have not previously been validated against tissue markers of choline metabolism, such as choline kinase (CHK±) from tumour specimens. METHOD: A prospective pilot study of 12 subjects, aged 18-80, with suspected primary supratentorial glioma suitable for biopsy and/or resection and a lesion diameter >2cm, recruited from Neuro-oncology MDT. The MRI protocol was performed at 3T, using a 32 channel head coil. PET/CT was then performed with 285MBq of 18F-FMC injected followed by dedicated brain dynamic list mode acquisition for 45 minutes. During surgery, 4-6 routine stereotactic biopsies were obtained. CHK± immunohistochemistry data is pending and will be presented in full at the conference. RESULTS: Preliminary data from 6 patients suggests spatial concordance between high 18F-FMC uptake on PET and more elevated choline/creatine ratio. Tissue data from 4 patients (2 low grade, 2 transforming gliomas) shows areas of high choline on imaging correlate with gliosis and macrophage infiltration, but not proliferative indices. CONCLUSION: Preliminary findings suggest choline PET and MRS detect inflammatory infiltrates rather than regions of high cellular proliferation.