There are different modalities of non-invasive imaging, we can make a first classification according to the type of information we can obtain with them, anatomical or functional. Imaging modalities can be combined in order to answer different questions. However a lot of expertise is required to be able to choose the appropriate modality and the imaging agents.
The different modalities include:
- Ultrasound Imaging (US): US provides 2D anatomical information. Combined with Doppler analysis, it allows evaluation of functional parameters, particularly in the cardiovascular and muscular fields. The spatial resolution ranges from 30 to 100 µm.
- X-ray Computed Tomography (CT): CT is well-suited for in vivo 3D analysis of bone tissue at a high level of spatial resolution (10 µm). Using specific contrast media, it can be used for anatomical, and, in some conditions, functional analysis of soft tissues. CT provides 3D anatomical images with spatial resolution ranging from 10 to 100 µm.
- Magnetic Resonance Imaging (MRI)
- Optical Imaging: Using fluorescent and bioluminescent probes, in vivo whole-body imaging provides images related to specific biochemical pathways. It is also well suited for biodistribution analysis, cell trafficking and functional genomics studies.
- Positron Emission Tomography (PET): The system detects pairs of gamma rays emitted indirectly by a positron-emitting radionuclide (tracer), which is introduced into the body on a biologically active molecule. Images of tracer concentration in 3-dimensional space within the body are then reconstructed by computer analysis.
- Single Photon Emission Tomography (SPECT): An increasing number of radioactive tracers are available (positron or „-emitters), permitting 3D whole-body evaluation of energy metabolism, biochemical pathways, ligand-receptor binding and antibody-antigen distribution. Spatial resolution is close to 1 mm.
- Photo Acoustic (Computed) Tomography (PAT/PACT): —-