Successful lymphoscintigraphy requires only the very smallest colloid particles (<0.1 mm). Unfiltered Tc-99m SC prepared by conventional methods results in unfavorable particle distribution- most particles are in range of 0.5-2.0 mm.

Preparation Methods

• Preparation Techniques for Sulfur Colloid 

  • boiling water bath for 5-10 min

  • microwave oven for 15-30 sec  

  • room temperature incubation for 1 hr
    

• Particle Size as f (Preparation Method)

  • boiling water bath:  mostly larger particles

  • microwave oven: wide range of particles, many small
    

  • room temperature incubation for 1 hr: mostly larger particles  

  
  

• General Preparation Method of Filtered Tc-99m SC

  • Reaction mixture heated in microwave oven with 28 sec heating cycle at 1/2 power (275 watts) OR in boiling water bath with 5 min heating cycle at 100^oC

  • Reaction mixture buffered, cooled 5-10 min

  • Tc-99m SC drawn into 10 ml syringe and filtered through two piggybacked  0.2 mm terminal filters into a sterile evacuated vial.  

    • Removal of Large Particles

    • Preferred method: Terminal filtration through a 0.2 mm disposable filter. Manufacturers: Burron Medical, Gelman, Millipore

  

  • Filtration step is repeated to remove particles missed by first filtration  

• Optimal Parameters for Routine Preparation for Tc-99m SC

  • In microwave oven, RCP > 98% routinely obtained with 28 sec heating cycle at 1/2 power (275 watts)

  • In boiling water bath, RCP > 98% routinely obtained with 5 min heating cycle at 100^oC

  •  Our in-house specification: RCP > 96%

• Optimal Preparation of 99mTcSC for Lymphoscintigraphy

  • Microwave 5 ml of reaction mixture containing 25 mCi ^99mTcO₄^- for 28 sec at 1/2 power (275 watts)

  • Add 1 ml of buffer, then cool for 5-10 min  

  • Draw Tc-99m SC into 10 ml syringe  

  • Filter through two 0.2 mm filters (piggy-backed) into sterile evacuated vial