3'-Deoxy-3'-[18F]fluorothymidine positron emission tomography for target delineation in resected malignant gliomas before radiotherapy

1838 Objectives To analysis the FLT PET image feature of malignant gliomas and evaluate the usefulness in the visualization of residual tumor volume compared with MRI. Methods Patients with postoperative residual malignant gliomas were enrolled on this prospective trial. MRI and PET were performed in the same week, 1-4 weeks after surgical resection.,we compared the SUVmax of tumor and the T/N ratio between the grade III and IV gliomas and the residual tumor volume and the geometric position defined by FLT uptake and the abnormalities signals on MRI were compared using FLT PET/MRI fusion images. Results 19 patients were analyzed . The SUVmax were 0.86±28 for grade III gliomas , and 2.68±2.22 or 2.05±0.44(with or without one gliosarcoma whose SUVmax was as high as 9.6) for grade IV gliomas (P 0.05). The areas between the increased FLT PET activity and abnormality in MRI were imperfectly correlated .In 13 (68.4%) and 11 patients(57.90%) , the FLT uptake regions exceeded the area of contrast enhancement and the area of hyperintensity areas on the MRI. In 5 (26.3%) and 4(21.05%) of 19 patients, FLT uptake extended 25 mm from the margin of Gd enhancement and hyperintensity areas. And the FLT uptake was measured up to 43mm and 39mm outside of the Gd enhancement and hyperintensity areas on MRI. Conclusions FLT PET was found to be useful in assessment of grade in malignant gliomas. FLT PET can provide complement information to the MRI for defining the remaining tumor volume accurately in patients with malignant gliomas postoperative residual.