<qa>  What is the importance of FDG-PET imaging in accurately characterizing disease?Cancer treatment and outcome depend largely on the accurate diagnosis and staging of disease. There is extensive data in the literature indicating the importance of FDG-PET imaging in accurately characterizing disease, as well as determining stage and sites of recurrent disease in many cancer types. For these indications, functional imaging with PET provides unique information which is not available from standard medical imaging modalities such as ultrasound, X-ray, computerized tomography CT or magnetic resonance imaging MRI. 