Spect Imaging

Single-photon emission computed tomography

  • True 3D information
  • Delivery of a gamma-emitting radioisotope
    • Radioisotope of gallium
    • Most of the time in SPECT, a marker radioisotope, which is of interest only for its radioactive properties, has been attached to a specific ligand to create a radioligand, which is of interest for its chemical binding properties to certain types of tissues.
    • Then (due to the gamma-emission of the isotope) allows the ligand concentration to be seen by a gamma-camera.
  • Use of radioactive materials (radiotracers) to assess the physiologic properties of organ systems (e.g. blood flow, glucose metabolism, or protein aggregates).
  • While planar single photon emission displays a single view of radiotracer distribution in patients (thyroid, ventilation/perfusion, or whole-body bone images); SPECT can display slice (2-dimensional) or volume (3-dimensional) images of radiotracer distribution, which is computed from multiple images taken with multiple cameras.
  • Radiotracers for brain SPECT scan:
    • Tc-99m HMPAO (Hexamethyl propyleneamine oxime)
    • Tc-99m ECD (ethyl cysteinate dimer)
    • I-123 isopropyliodoamphetamine (IMP)
    • Thallium-201 diethyldithiocarbamate (T1-DDC).