**3. In Vivo Imaging**

In clinical practice, CT, PET, ultrasonography, and MRI are essential for the diagnoses and monitoring of neoplastic diseases. In preclinical experimental models, these modalities provide functional and metabolic imaging and pathophysiological information beyond morphology, as well as the ability to study molecular events. In both clinical and preclinical areas, imaging modalities contribute to the oncology field by being reliable indicators for early tumoral responses to therapy, and they can guide effective therapies, or stratify patients [79,80]. General anesthesia is usually needed, in the case of imaging, to obtain immobility of the mouse, and to abolish the stress due to the loud noise, especially that produced by MRI [20].
