Can diffusion weighted magnetic resonance imaging (DW-MRI) be an alternative to 18f-FDG PET/CT (18f fluorodeoxyglucose positron emission tomography) in nasopharyngeal cancers?

Objective: This study aimed to evaluate correlations, if any, between the ADC (Apparent Diffusion Coefficient) measurements in MRI (Magnetic Resonance Imaging) and SUV max (Standardized Uptake Value) in F-18-FDG PET/CT in patients with nasopharyngeal cancers and to investigate whether DW-MRI (Diffusion Weighted MRI) can be an alternative to F-18-FDG PET/CT in the evaluation of the response to treatment and prognosis in those patients. Methods: This study was performed between January 2015 and February 2016 at Inonu University Medical Faculty, Department of Radiology on 22 patients who were diagnosed with nasopharyngeal cancer by histopathological evaluation at Department of Pathology of the same faculty. Diffusion weighted images were obtained using 1.5 T MRI in all patients. F-18-FDG PET/CT images were obtained approximately 1-2 weeks after the diffusion-weighted images. Results: Two groups were created according to the histological subtypes as keratinized (n: 8) and non-keratinized (n: 14) among the 22 cases with a definitive histopathological diagnosis of nasopharyngeal cancer. No statistical difference was found between the groups in terms of SUVmax, SUVmean and ADC mean values (p> 0.05). ADC mean values measured in patients with nasopharyngeal cancer were statistically significantly and negatively correlated with SUV max (r=-0.619, p< 0.001) and SUV mean values (r=-0.677, p< 0.001). Conclusion: Even though there are anatomic and patient-related limitations of the DW-MRI in nasopharyngeal cancers, we suggest that it may be a complementary and alternative method of F-18-FDG PET/CT in the evaluation of treatment response and prognosis detection in nasopharyngeal cancers.