<unk>  is the visualization of living animals for research purposes, such as drug development.<unk>  modalities have long been crucial to the researcher in observing changes, either at the organ, tissue, cell, or molecular level, in animals responding to physiological or environmental changes.<unk>  modalities that are non-invasive and in vivo have become especially important to study animal models longitudinally. Broadly speaking, these<unk>  systems can be categorized into primarily morphological/anatomical and primarily molecular<unk>  techniques. Techniques such as high-frequency micro-ultrasound, magnetic resonance<unk>  (MRI) and computed tomography (CT) are usually used for anatomical<unk> , while optical<unk>  (fluorescence and bioluminescence), positron emission tomography (PET), and single photon emission computed tomography (SPECT) are usually used for molecular visualizations. These days, many manufacturers provide multi-modal systems combining the advantages of anatomical modalities such as CT and MR with the functional<unk>  of PET and SPECT. As in the clinical market, common combinations are SPECT/CT, PET/CT and PET/MR.
Preclinical imaging
Animal testing
Acoustic epidemiology
Disease surveillance
Ultrasound research interface
ReSPECT process
Clinical epidemiology
Imaging biomarker