Correlation between functional imaging markers derived from diffusion-weighted MRI and 18F-FDG PET/CT in esophageal cancer

OBJECTIVE: Both the apparent diffusion coefficient (ADC) acquired by diffusion-weighted magnetic resonance imaging (DW-MRI) and the standardized uptake value (SUV), acquired by F-fluorodeoxyglucose positron emission tomography/computed tomography (F-FDG PET/CT), are well-established functional parameters in cancer imaging. Currently, it is unclear whether these two markers provide complementary prognostic and predictive information in esophageal cancer. The aim of this study was to evaluate the correlation between ADC and SUV in patients with esophageal cancer. MATERIALS AND METHODS: This prospective study included 76 patients with histologically proven esophageal cancer who underwent both DW-MRI and F-FDG PET/CT examinations before treatment. The minimum and mean ADC values (ADCmin and ADCmean) of the primary tumor were assessed on MRI. Similarly, the glucose metabolism was evaluated by the maximum and mean SUV (SUVmax and SUVmean) in the same lesions on F-FDG PET/CT images. Spearman's rank correlation coefficients were used to assess the correlation between tumor ADC and SUV values. RESULTS: The tumor ADC and SUV values as measures of cell density and glucose metabolism, respectively, showed negligible nonsignificant correlations (ADCmin vs. SUVmax: r=-0.087, P=0.457; ADCmin vs. SUVmean: r=-0.105, P=0.369; ADCmean vs. SUVmax: r=-0.099, P=0.349; ADCmean vs. SUVmean: r=-0.111, P=0.340). No differences in tumor ADC and SUV values were observed between the different histologic tumor types, stages, and differentiation grades. CONCLUSION: This study indicates that tumor cellularity derived from DW-MRI and tumor metabolism measured by F-FDG PET/CT are independent cellular phenomena in newly diagnosed esophageal cancer. Therefore, tumor ADC and SUV values may play complementary roles as imaging markers in the prediction of survival and evaluation of response to treatment in esophageal cancer.