Objective: This study evaluates the relation between 2-deoxy-2-[18F]fluoro-D: -glucose (FDG) uptake using positron emission tomography/CT and the apparent diffusion coefficient (ADC) in patients with glioma and malignant lymphoma.
Methods: For 36 patients (30 with glioma and 6 with malignant lymphoma), the standardized uptake value (SUV) ratio was calculated to assess the FDG uptake. Pearson's correlation analysis was used to assess the relation between the SUV ratio and the ADC value: those of low-grade glioma and high-grade glioma were compared, as were those of glioblastoma and malignant lymphoma.
Results: Inverse correlation between the SUV ratio and the minimum ADC was found for all cases (P < 0.0001, r = 0.68) and for glioma cases (P < 0.0001, r = 0.67). High-grade gliomas showed a significantly higher SUV ratio than low-grade gliomas did (P < 0.0001); they also showed significantly lower minimum ADC than low-grade gliomas did (P < 0.001). Cut-off values used for the SUV ratio of 0.9 and for the minimum ADC of 0.99 × 10(-3 )mm(2)/s were used to differentiate high-grade from low-grade gliomas, with high accuracy. Malignant lymphoma showed a significantly higher SUV ratio than glioblastoma (P < 0.0001). No significant difference in the ADC value was found between glioblastoma and malignant lymphoma (the minimum ADC: P = 0.13, the mean ADC: P = 0.084, respectively).
Conclusions: An inverse correlation was found between the SUV ratio and the minimum ADC in glioma and malignant lymphoma. The SUV ratio and the minimum ADC are useful to evaluate the grading of gliomas. The SUV ratio might be more useful for differentiating malignant lymphoma from glioblastoma than the ADC value is.