Differentiation of residual or recurrent tumors from post-treatment changes with F-18 FDG PET.

Pseudoprogression, radionecrosis, inflammation or true tumor progression? challenges associated with glioblastoma response assessment in an evolving therapeutic landscape

“…Studies using radiolabeled fluorodeoxyglucose ( 18 F-FDG), a surrogate of glucose metabolism, have demonstrated significantly higher uptake in recurrent disease compared with pseudoprogression with high sensitivity and specificity [42,43]. PET imaging of neutral amino acid transport or metabolism, including 11 C-methionine ( 11 C-MET) [44], 18 F-fluorodopa ( 18 F-FDOPA) [45], and 18 F-fluoro-ethyltyrosine ( 18 F-FET) [46,47], have also shown value in differentiating pseudoprogression from tumor with higher lesion conspicuity due to lower background activity in normal brain.…”

Imaging in neurooncology

“…145,146 Similar to structural imaging, the effects of radio-and chemotherapy can be visualized by [ 18 F]FDG-PET only after several weeks 147 with a possible transient increase of [ 18 F]FDG-uptake in the initial phase which is most likely due to infiltration of macrophages consuming [ 18 F]FDG. 148 -150 At further followup, however, recurrent tumor and progression from lowgrade to high-grade glioma can be visualized by a newly appearing hypermetabolism.…”

Oncological applications of positron emission tomography with fluorine-18 fluorodeoxyglucose

“…Differentiation of scar and residual or recurrent disease is a frequent indication for PET and one of the first to be documented [88]. In 1988, Di Chiro et al showed the value of FDG PET in distinguishing radiation necrosis from recurrent tumour in the brain [89,90].…”