E1223. 18F-Fluoroethyl-L-Tyrosine PET/MRI Assessment of Treatment Response in Brain Malignancies
Princess Alexandra Hospital
18F-Fluoroethyl-L-Tyrosine (FET) is an artificial amino acid, which is taken up by malignant cells. FET is particularly useful due to the low uptake in normal brain tissue; however, research of FET in treatment response is limited. Animal experiments have shown that FET exhibits no uptake in inflammatory cells and macrophages. Theoretically, this would allow for high specificity in residual tumor detection.
Materials and Methods:
This pilot trial recruited 35 patients with pathologically or radiologically proven brain malignancy. Patients were then treated with either gamma-knife or surgery. Following treatment, patients underwent FET PET/MRI with secondary MRI processing, which included perfusion, permeability, and spectroscopy. Assessment of disease progression versus treatment response was undertaken with MRI at one and three months.
Thirty patients have undergone assessment to date. FET-PET has shown similar sensitivity and specificity to MRI, but only when used in conjunction with perfusion, permeability, and spectroscopy. In two patients, FET-PET suggested residual disease, whereas MRI suggested treatment response. On follow-up, this was shown to be disease progression. Complete results will be provided for the scientific presentation.
Research with FET-PET in treatment response is limited; however, FET-PET has shown promise to differentiate residual tumor from treatment response in problematic cases.