In metastatic differentiated thyroid cancer (MDTC) the radioiodine treatment is a consolidated approach. The effectiveness of the therapy can be verified on post administration tomography imaging. Aim of this study is to evaluate the feasibility and prognostic impact of 131I SPECT-CT images features analysis (FA) performed on metastatic lesion in MDTC patients. FA is performed on SPECT-CT images with a free software (LIFEx, CEA 2017) taking into account texture features (TF) and first-order features (FF). TF include Gray-Level Occurrence Matrix GLCM (e.g. homogeneity, contrast) and Gray-Level Zone Length Matrix GLZLM (e.g. HGZE); FF include histograms indices (e.g. skewness, kurtosis and entropy).