[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] Non-invasive imaging techniques have been recently developed to characterize animal models of disease. The overarching hypothesis of this work explores the use of three micro-imaging modalities, including Micro-CT, PET and SPECT, to characterize tumor anatomical progression, metabolism, bone lesion remodeling, and/or gastrin releasing peptide receptor expression in mouse models of metastatic melanoma and prostate and breast cancer bone metastasis. Micro-CT was shown to provide excellent anatomical information about tumor progression in several different tissues including lung, bone, and subcutaneous tissues. Micro-PET imaging demonstrated increased tumor metabolism in melanoma tumors, but was not able to discern bone remodeling in breast cancer bone lesions. Micro-SPECT imaging demonstrated gastrin-releasing peptide receptor expression in a prostate cancer bone metastasis model. The results from this work demonstrate the ability of micro-imaging technologies to non-invasively probe mouse models of disease to obtain information in vivo that is not possible with ex vivo experimental techniques.