29 - Radionuclide Imaging of Reporter Gene Expression

Abstract

This chapter reviews the instrumentation for molecular imaging focusing on the approaches to using reporter gene technology with radionuclide imaging technologies such as positron emission tomography (PET) and single-photon-emission computed tomography (SPECT). In many of the imaging applications, reporter genes have been driven by a constitutive exogenous promoter such as the cytomegalovirus (CMV) promoter, which allows for continuous transcription of the reporter gene, but does not allow for tracking of endogenous gene expression. A reporter gene can be linked to any endogenous promoter of choice and, therefore, the endogenous gene promoter can modulate expression of the reporter gene. PET reporter gene imaging in transgenic animals and assessment of the transcriptional regulation of such an endogenous gene through imaging the suppression and induction of reporter gene expression demonstrated the feasibility of indirectly imaging endogenous gene expression. Imaging mRNA levels with antisense reporter probes may be a very useful approach for many applications. The use of antisense reporter probes would be particularly useful for endogenous genes, because unlike the reporter gene imaging approach it is not necessary to introduce any reporter vectors.