18F-FDG PET/CT Prognostic Parameters in Patients with Head and Neck Cancer.

In head and neck cancer, computed tomography (CT) magnetic resonance (MR) imaging are routinely used. However 18F FDG PET-CT has been shown to have higher sensitivity and a high negative predictive value for identification of small lymph nodes of the neck especially using the volume of 18F-FDG - avid disease (MTV) and the total lesion glycolysis (TLG) as a prognostic indicator. Metastasis in HNSCC is relatively low and it implies a poor prognosis and has a major impact on patient management. Additionally, patients with HNSCC have a higher prevalence of synchronous and metachronous primary tumors, which can be detected at FDG PET/CT. 18F-FDG PET is the most sensitive noninvasive modality presently available for differentiating post-treatment changes regardless of the primary treatment modality used from residual or recurrent disease as compared to CT and MR. PET-CT hypoxic imaging is a growing diagnostic modality as Hypoxia represents a negative prognostic factor for radiation treatment where it is associated with a significant resistance to radio-chemotherapy. Several PET tracers have emerged for this purpose like (18F-FMISO), (18F-FAZA). Radiomics as an emerging technology concerned with extraction of numerous quantitative parameters by extraction features from different imaging modalities (CT, MRI, and PET-CT). Radiomics commonly describe shape; intensity and texture characterization and it provide fast, cost-effective non-invasive comprehensive tissue characterization that offer complementary information to conventional clinical and imaging modalities.