Molecular imaging is a new biomedical research discipline enabling the visualization, characterization, and quantification of biologic processes taking place at the cellular and sub-cellular levels within intact living subjects including patients.
Molecular imaging includes the field of nuclear medicine along with various other fields that together offer an array of different strategies to produce imaging signals. Whereas nuclear medicine uses radio-labeled molecules (tracers) that produce signals by means of radioactive decay only, molecular imaging uses these as well as other molecules to image via means of sound (ultrasound), magnetism (MRI or magnetic resonance imaging), or light (optical techniques of bio-luminescence and fluorescence) as well as other emerging techniques.
The main limitation of most of these specific approaches is that a new substrate must be discovered and radio-labeled to yield a different probe for each new protein target. With the significant difficulty, cost, and effort involved in radio-labeling new substrates, along with the requirement for in vivo characterization of every such substrate under investigation, more generalizable methods are preferred.
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