An automated voxel-based method for calculating the reference value for a brain tumour metabolic index using 18F-FDG-PET and 11C-methionine PET

Abstract

ObjectiveThe tumour-to-normal ratio (T/N) is a representative index reflecting brain tumour activity by 18F-fluorodeoxyglucose (FDG) and 11C-methionine (MET) PET. We proposed a new automated method of calculating the normal reference value (N-value) for use as the denomination of T/N. This method uses voxel-based analysis of FDG- and MET-PET images. We compared the results of this method with those of the standard region-of-interest (ROI) method.MethodsData sets were obtained from 32 patients with newly diagnosed glioma and 13 patients with recurrent brain tumour. Our methods were as follows: (1) FDG-PET and MET-PET images were co-registered. (2) The areas where the FDG uptake was higher than a set threshold were selected. (3) For the corresponding areas of MET-PET images, mode and mean voxel values were calculated as tentative MET N-values. (4) Applying the same coordinates to FDG-PET, the voxel values were averaged and used as tentative FDG N-values. (5) The threshold of FDG-PET and whether to use the mode or the mean voxel values were computationally optimized using learning data sets. (6) Applying the optimal threshold and either the mode or mean, N-values of FDG and MET were finally determined.ResultsN-values determined by our automated method showed excellent agreement with those determined by a manual ROI method (ICC(2,1) > 0.78). These values were significantly correlated with mean manual N-values (p < 0.001).ConclusionsOur new method shows sufficiently good agreement with the standard method and can provide a more objective metabolic index.Electronic supplementary materialThe online version of this article (doi:10.1007/s12149-017-1153-8) contains supplementary material, which is available to authorized users.

A Non-invasive Radiomic Method Using 18F-FDG PET Predicts Isocitrate Dehydrogenase Genotype and Prognosis in Patients With Glioma

“…This imaging method provides additional insight beyond MR imaging (MRI) into the biology of gliomas, which facilitates the analysis of the tumor from the perspective of glucose metabolism. In glioma research, 18 F-FDG PET is widely applied, for example for tumor grading (24), determination of tumor extent (25), surgical planning (26), differentiation of tumor progression and necrosis (27), and prognosis prediction (28). However, to the best of our knowledge, few studies have used 18 F-FDG PET images and the radiomic method to predict IDH genotype.…”