Figure 2. The extraction process and general characteristics of pre-treatment PET signatures with HNSCC patients. (A) The segmentation and reconstruction process of PET/CT images. (B) Demonstration of the varies of Lasso coefficient in different log (λ) sequence. A 15-fold cross validation were used to select the most optimal penalty parameter λ via minimum criteria. The minimum λ (λ = 0.05209914) were chose according to the criteria. Abbreviations: OS: overall survival. DFS: disease free survival.