“…Positron emission tomography (PET) and single-photon emission computed tomography (SPECT) employ radiopharmaceuticals to provide three-dimensional images of the tracer molecules. , Both imaging techniques have the capability to track chemical changes, such as sugar metabolism and antisense recognition, with significant depth penetration. The distinction lies in the detection mechanism: in PET, two oppositely directed photons are detected by the scanner, which offers picomolar sensitivity but is constrained by the limited availability of imaging reagents, such as 18 F. In SPECT, however, the detectors can capture γ rays emitted from various radiolabeled tracers with a corresponding decrease in imaging precision …”