Tc-99m sulfur colloid

Last revised by Andrew Murphy on 03 Apr 2020

Technetium-99m sulfur colloid is one of the technetium radiopharmaceuticals.


  • photon energy: 140 keV
  • physical half-life: 6 hours
  • biological half-life
  • normal distribution:
    • liver: 85%
    • spleen: 10%
    • bone marrow: 5%
  • excretion: hepatic
  • target organ: liver, spleen
  • pharmacokinetics:
    • rapid extraction by liver, spleen, and bone marrow
    • active bleeding increases in conspicuity as background clears
    • small colloid particles (0.1-1.0 micrometer) extracted by reticuloendothelial system (RES)
    • localization is flow-dependant
    • taken up by Kupffer cells in the liver
  • miscellaneous facts

Uses, dosages and timings

  • dose: 4-8 injections of 3.7 MBq (100 μCi) injected intradermally
    • encircling the lesion site for a melanoma study
    • in the webs of the fingers and toes for a lymphatic mapping study
  • time of imaging: immediately after the last injection
Gastric emptying scan
  • adult dose: 37MBq (1 mCi) in meal
    • a meal of chicken liver was the original gold standard, but it is more common to use a scrambled egg, oatmeal, pancake, or an egg sandwich; many things have been used and each facility decides what should be defined as a normal meal for their patients
  • pediatric dose: 1.11-1.85 MBq/kg (30-50 μCi/kg), minimum 18.5 MBq (500 μCi)
  • time of imaging: immediate
  • length of imaging: 2-4 hours
Liver / spleen scan
  • adult dose: 148-296 MBq (4-8 mCi) IV
  • pediatric dose: 1.11-1.85 MBq/kg (30-50 μCi/kg) minimum 11.1 MBq (300 μCi)
  • time of imaging: 20 min
Gastrointestinal tract bleeding
  • adult dose: 370 MBq (10 mCi) IV
  • time of imaging: immediate (1 sec frames x 60 sec; 1-2 min frames x 20 min)

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Cases and figures

  • Splenosis mimicking metastatic prostate cancer
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  • Intrathoracic splenosis
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