18f-faza and Glioblastoma

Glioblastoma (GB) is the most common primary malignant brain tumor. Standard medical treatment consists of a maximal safe surgical resection, subsequently radiation therapy (RT) and chemotherapy with temozolomide (TMZ). An accurate definition of the tumor volume is of utmost importance for guiding RT. In this project we investigated the feasibility and treatment response of subvolume boosting to a PET-defined tumor part.. F98 GB cells inoculated in the rat brain were imaged using T2- and contrast-enhanced T1-weighted (T1w) MRI. A dose of 20 Gy (5 × 5 mm. When comparing the dose volume histograms, a significant difference was found exclusively between the D. In this study we showed the feasibility of PET guided subvolume boosting of F98 glioblastoma in rats. No evidence was found for a beneficial effect regarding tumor response. However, improvements for dose targeting in rodents and studies investigating new targeted drugs for GB treatment are mandatory.

Topics: Animals; Brain Neoplasms; Cell Line, Tumor; Disease Models, Animal; Feasibility Studies; Female; Glioblastoma; Nitroimidazoles; Positron-Emission Tomography; Radiopharmaceuticals; Radiotherapy Dosage; Radiotherapy, Image-Guided; Rats, Inbred F344; Treatment Outcome; Tumor Burden; Tyrosine

The prognosis of malignant gliomas remains largely unsatisfactory for the intrinsic characteristics of the pathology and for the delayed diagnosis. Multimodal imaging based on PET and MRI may assess the dynamics of disease onset and progression allowing the validation of preclinical models of glioblastoma multiforme (GBM). The aim of this study was the characterization of a syngeneic rat model of GBM using combined in vivo imaging and immunohistochemistry.. Four groups of Fischer rats were implanted in a subcortical region with increasing concentration of rat glioma F98 cells and weekly monitored with Gd-MR, [(18)F]FDG- and [(18)F]FAZA-PET starting one week after surgery. Different targets were evaluated on post mortem brain specimens using immunohistochemistry: VEGF, GFAP, HIF-1α, Ki-67 and nestin.. Imaging results indicated that tumor onset but not progression was related to the number of F98 cells. Hypoxic regions identified with [(18)F]FAZA and high-glucose metabolism regions recognized with [(18)F]FDG were located respectively in the core and in external areas of the tumor, with partial overlap and remodeling during disease progression. Histological and immunohistochemical analysis confirmed PET/MRI results and revealed that our model resumes biological characteristics of human GBM. IHC and PET studies showed that necrotic regions, defined on the basis of [(18)F]FDG uptake reduction, may include hypoxic clusters of vital tumor tissue identified with [(18)F]FAZA. This last information is particularly relevant for the identification of the target volume during image-guided radiotherapy.. In conclusion, the combined use of PET and MRI allows in vivo monitoring of the biological modification of F98 lesions during tumor progression.

Topics: Animals; Cell Differentiation; Cell Line, Tumor; Disease Models, Animal; Fluorodeoxyglucose F18; Glioblastoma; Humans; Magnetic Resonance Imaging; Male; Nitroimidazoles; Positron-Emission Tomography; Rats; Survival Analysis