Gallium-67 (Ga-67) is a photon-emitting radiotracer used for scintigraphy which is used in the form of various salts like citrate and nitrate. Once administered, imaging may consist of planar (2 dimensional), SPECT, and SPECT-CT acquisitions. Once injected it binds to plasma proteins (especially transferrin and lactoferrin), and has a predilection to sites of inflammation. It binds to inflammatory proteins and thus it pools up at the sites of various inflammatory and granulomatous reactions.
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Radionuclide profile
emits a spectrum of gamma rays (93, 185, 288, 394 KeV energy)
half life is about 78 hours
critical organ: bone surfaces (ICRP 128)
normal distribution is seen in the liver, bone marrow and spleen
Uses
localization of source of fever in cases of fever of unknown origin (FUO)
bleomycin and amiodarone induced pulmonary toxicity
spinal osteomyelitis
non-specific tumor imaging agent (used in lymphomas in the past, before advent of F-18 FDG PET-CT)
Technique
imaging can be done at 24, 48, and 72 hours.
study may include planar, SPECT and SPECT-CT imaging
has largely been replaced by 18-F FDG PET-CT imaging which has the advantage of earlier scan, better image quality, and SUV quantification
Advantages and disadvantages
Advantages
better in evaluation of spinal infection than other tagged WBC radiotracers
gallium citrate usually shows a negative scan earlier than other radionuclide like technetium used in bone scanning
Disadvantages
higher radiation dose than other WBC radiotracers
poor image quality
cannot differentiate between osteomyelitis and cellulitis