Background:In differentiated thyroid cancer (DTC) patients, cervical nodal metastasis is a negative prognostic factor. Preoperative imaging plays an important role in treatment planning for nodal metastasis and recurrence.The aim of the study is to compare the diagnostic performance of the diffusion-weighted magnetic resonance imaging (DW-MRI) and the F-18 flurodeoxyglucose positron emission computed tomography ([ 18 F]FDG PET/CT) in detection of cervical nodal deposits in DTC patients. Materal and methods:The study was conducted on 30 patients, each performed both modalities just before the surgery. The gold standard was the pathological specimens with post-operative clinico-radiological follow-up, to assess the diagnostic performance of each modality. Results:Based on pathological and post-operative clinico-radiological follow up data. Sensitivity, specificity, negative predictive value (NPV), positive predictive value (PPV) and accuracy were 84%, 80%, 50%, 95% and 83% for PET/CT compared to 84%, 60%, 42.8%, 91.3% and 80% for DW-MRI.On comparing the diagnostic performance of combined DW-MRI and PET/CT to each modality alone, the sensitivity and NPV were improved to 96% and 80% respectively.Conclusions: [ 18 F]FDG PET/CT study is a valuable diagnostic modality for the assessment of cervical nodal deposits in DTC patients, surpassing DW-MRI. Combined PET/CT and DW-MRI techniques seemed to have synergistic performance, mainly in terms of sensitivity and NPV, for detection of nodal metastases.