Single Photon Emission Computed Tomography
Unlike positron emission tomography (PET), which relies on 511 KeV coincidences resulting from positron and electron annihilations, single photon emission computed tomography (SPECT) detects a wide range of gamma rays from 10 KeV to 300 KeV (the range can be broadened by specific aperture as necessary). Simply put, it provides a “spectrum-like” readout, which enables in vivo imaging of multiple biological events or different components of a single injection.
Of course, distinct radioisotopes with differentiable gamma ray emission energies are required for the “multi-isotope” imaging. (The gamma energy resolution of our NanoSPECT/CT Plus system is 14-KeV.) These radioisotopes include: 99mTc (t1/2= 6.01 h; γ (89%): 141 KeV); 125I (t1/2= 59.4 d; γ (7%): 36 KeV); 123I (t1/2= 13.2 h; γ (83%): 159 KeV); 111In (t1/2= 2.8 d; γ (94%): 245 KeV); 67Ga (t1/2= 3.3 d; γ (38%): 93 KeV); and 198Au (t1/2= 2.7 d; γ (7%): 412 KeV). “Multi-isotope” imaging is of special value to in vivo identification of cancer stem cells, monitoring nanomedicine integrity or payload release, and evaluating correlations of seemingly “distinctive” biological events in the metabolic milieu of live subjects.
It is the research interest of the Preclinical Nuclear Imaging Laboratory to design and synthesize novel and existing SPECT probes. However, a cost-sharing arrangement must be made if non-commercially available probes are needed.