In vivo imaging has become an essential tool in cancer research, clinical trials, and medical practice. Recent advances in high-resolution fluorescent imaging and MR/PET/CT image registration, combined with new molecular probes, allow bridging of physical scales from single cells to macroscopic levels. This enables translation of basic science insights to clinical applications. The article discusses recent advances in imaging at macro- and micro-scales, highlighting how these advances are synergistic with new imaging agents, reporters, and labeling schemes. Examples of new insights from different imaging scales are discussed in the context of cancer progression and metastasis. Macroscopic imaging technologies such as MRI, PET, SPECT, and CT are widely used in clinical practice for anatomic and physiological imaging. These technologies have been adapted for use in experimental mouse models, enabling the development of new translational imaging probes. Hybrid imaging platforms like PET-CT, FMT-CT, and PET-MRI are being developed to improve data reconstruction and visualization. MRI provides excellent soft tissue contrast and is used for imaging many cancers. PET imaging detects positrons from radiotracers and is used for cancer staging and treatment response monitoring. Fluorescence imaging systems, including FMT and FPT, are used for molecular imaging and can provide quantitative data. Bioluminescence imaging is useful for small animal studies and can detect gene expression and therapy responses. Microscopic imaging techniques such as confocal and multiphoton microscopy allow for high-resolution imaging of tumor cells and their interactions with the microenvironment. These techniques have been adapted for in vivo imaging, enabling the study of tumor progression and metastasis at the single cell level. New techniques have extended the duration of intravital imaging, allowing for the study of cell-cell and cell-extracellular matrix interactions. The development of new multiphoton microscope designs has enabled the visualization of far-red fluorescent proteins and other probes, improving deep tissue imaging. Support software for multiphoton 4D imaging has been developed to facilitate the analysis of cell movement and interactions. Genetic reporter strategies, radiotracer, fluorochrome, and biorthogonal labeling techniques are used to label cells and molecules for in vivo imaging. These techniques allow for the visualization of tumor cells and their interactions with the microenvironment. Applications in cancer biology and clinical oncology include the study of invasion and metastasis, the correlation of tumor cell behavior with gene expression and clinical markers of metastatic risk, and the fate mapping of tumor cells at high resolution in vivo. These advances have significant implications for the understanding of cancer progression and the development of new therapeutic strategies.In vivo imaging has become an essential tool in cancer research, clinical trials, and medical practice. Recent advances in high-resolution fluorescent imaging and MR/PET/CT image registration, combined with new molecular probes, allow bridging of physical scales from single cells to macroscopic levels. This enables translation of basic science insights to clinical applications. The article discusses recent advances in imaging at macro- and micro-scales, highlighting how these advances are synergistic with new imaging agents, reporters, and labeling schemes. Examples of new insights from different imaging scales are discussed in the context of cancer progression and metastasis. Macroscopic imaging technologies such as MRI, PET, SPECT, and CT are widely used in clinical practice for anatomic and physiological imaging. These technologies have been adapted for use in experimental mouse models, enabling the development of new translational imaging probes. Hybrid imaging platforms like PET-CT, FMT-CT, and PET-MRI are being developed to improve data reconstruction and visualization. MRI provides excellent soft tissue contrast and is used for imaging many cancers. PET imaging detects positrons from radiotracers and is used for cancer staging and treatment response monitoring. Fluorescence imaging systems, including FMT and FPT, are used for molecular imaging and can provide quantitative data. Bioluminescence imaging is useful for small animal studies and can detect gene expression and therapy responses. Microscopic imaging techniques such as confocal and multiphoton microscopy allow for high-resolution imaging of tumor cells and their interactions with the microenvironment. These techniques have been adapted for in vivo imaging, enabling the study of tumor progression and metastasis at the single cell level. New techniques have extended the duration of intravital imaging, allowing for the study of cell-cell and cell-extracellular matrix interactions. The development of new multiphoton microscope designs has enabled the visualization of far-red fluorescent proteins and other probes, improving deep tissue imaging. Support software for multiphoton 4D imaging has been developed to facilitate the analysis of cell movement and interactions. Genetic reporter strategies, radiotracer, fluorochrome, and biorthogonal labeling techniques are used to label cells and molecules for in vivo imaging. These techniques allow for the visualization of tumor cells and their interactions with the microenvironment. Applications in cancer biology and clinical oncology include the study of invasion and metastasis, the correlation of tumor cell behavior with gene expression and clinical markers of metastatic risk, and the fate mapping of tumor cells at high resolution in vivo. These advances have significant implications for the understanding of cancer progression and the development of new therapeutic strategies.