Magnetic Resonance Imaging (MRI): A noninvasive medical imaging technique that uses strong magnetic fields, magnetic field gradients and radio waves to generate images of the internal structures of the body.  

*When to consider using MRI: MRI is considered the gold standard for soft tissue imaging.  It has relatively high spatial resolution and does not suffer from depth of penetration, allowing all soft tissues of body to be imaged.  This modality is ideally suited for the study of cancer biology, neurology and those studying various organs such as the kidneys, liver and reproductive organs.

Computed Tomography (CT) Imaging: A medical imaging technique that uses a combination of x-rays and computer technology to produce images of the internal structures of the body.

*When to consider using CT: CT imaging has poor soft tissue contrast and is therefore us typically  recommended for bone imaging and lung imaging.  It is best suited for those wanting skeletal structure imaging and those studying diseases of the lung.

Bioluminescence and Fluorescence Imaging: Highly sensitive optical imaging techniques.  Bioluminesce imaging typically takes advantage of the enzymatic reaction that occurs when a  luciferin substrate is injected into a subject expressing the luciferase enzyme.  The resulting reaction produces light and can be useful in the detection and tracking of tumor cells.  Fluorescence imaging requires that either a fluorophore is expressed by specific cells or that a fluorescent agent is introduced.  Autofluorescence from tissues, bone, fur, etc, can be an issue, reducing the sentitivity and usefulness of this technique in whole animal models.

*When to consider using bioluminescence imaging: Bioluminescence imaging is mostly widely use in tumor models.  Once cells expressing the enzyme are introduced into an animal they can be detected with a high level of sensitivity.  Models may be subcutaneouos, orthotopic and/or metastic in nature.

*When to consider using fluorescence imaging: In vivo fluorescence imaging is most successful when a long fluorophore wavelength is employed and detection is needed at the subcutaneous level.  Autofluorescence makes deep signals difficult to detect and reduces overall sensivity of this imaging technique.