Clinical And Animal Experimental Study On Multiple Imaging In Brain Tumor

PartⅠ Clinical Study on18F-FLT and18F-FDG PET/CT in Brain TumorObjective: The aim of this study was to evaluate the feasibility of using18F-2-fluoro-2-deoxy-D-glucose(18F-FDG) and3-deoxy-3-18F-fluorothymidine(18F-FLT)positron emission tomography (PET) for the diagnosis and grading of brain tumors.Methods: The patient population comprised24patients with brain tumors ornontumorous lesions.18F-FDG and18F-FLT PET/CT images were obtained. Uptake of18F-FDG and18F-FLT were analyzed semiquantitatively using the maximal standardizeduptake value (SUVmax), lesion to normal(T/N), lesion to gray matter(T/G), lesion towhite matter(T/W).Results:Of24brain lesions, SUVmax and L/W of FLT between high and low gradetumors were significantly different.However,the L/N、L/G of FLT and the SUVmax、L/N、L/G and L/W of FDG had no differences.The SUVmax、 L/G and L/W of FLT weresignificantly different between high grade tumors and nontumorous lesions,but L/N ofFLT and SUVmax、L/N、L/G、L/W of FDG had no differences.The SUVmax、L/N、L/G and L/W of both tracers were not different between nontumorous lesions and lowgrade tumors,neither between high grade glioma and metastatic tumor.Conclusion: These findings indicate that FLT PET is useful for evaluating tumor gradeand cellular proliferation in brain tumors.Part II Study on early radiation-induced brain injury in rats and ratC6glioma model by using PET and MRIObjective: To investigate normal MRI,DWI,MRS and18F-FDG,18F-FLT PET/CTfeatures of rat early radiation-induced brain injury and rat C6glioma model.Material and Methods: Twenty five male Sprague-Dawley rats receive irradiation of55 Gy to the left hemibrains with a single highly collimated (square field of1cm×1cm，SSD100cm)6MV photon beam from a linear accelerator under anesthesia. All rats werescanned with FSE T2WI,DWI, and MRS sequences at the end of1,2,6,12and16weeks.Parameters were compared with normal group and the pathology of rat brains.SD ratswere stereotaxically implanted into the both side inguinal regions and received18F-FDG,18F-FLT PET/CT3weeks later.Results:Mean ADC values of bilateral parietal lobe decreased gradually. At the end of the6th week, they were lowest,then rise at the end of the12thweek. MRS showed that afterradiation, Cho/Cr increased and NAA/Cr decreased.The SUVmax of18F-FDG PET/CTbetween tumor and muscle was different,but the SUVmax of18F-FLT PET/CT has nodifference.Conclusion：The model of radiation-induced brain injury in this experiment is simple,rats can tolerate, but still need to strengthen the accurate positioning, can be appropriatelyincreased exposure dose, longer observation time.DWI and MRS can be more sensitivemethod of MRI can display the seemingly normal parenchymal tiny lesions, fromdifferent angles reflects the change of early radiation brain injury.18F-FDG,18F-FLTPET/CT for differentiating radiation brain injury and normal brain tissue no significanteffect, but can be a very good to identify tumor and surrounding normal tissues.