Tc-99m sulfur colloid

Last revised by Travis Fahrenhorst-Jones on 21 Dec 2022

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

Characteristics

  • photon energy: 140 keV

  • physical half-life: 6 hours

  • biological half-life: 2 to 3 minutes

  • 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

    • colloid shift in severe liver dysfunction

    • all hepatic masses except focal nodular hyperplasia (FNH) are cold

    • technetium-99m sulfur colloids may be prepared from sodium thiosulphate in an acidic medium, or sodium dithionite in a neutral medium via reduction of technetium at an elevated temperature 1

    • technetium-99m-rhenium-sulphide can also be prepared at an elevated temperature from sodium thiosulphate in the presence of hydrocholic acid and potassium perrhenate 1

Uses, dosages and timings

Lymphoscintigraphy
  • 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

  • Case 1: splenosis mimicking metastatic prostate cancer
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  • Case 2: intrathoracic splenosis
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