Sn (II) ion requirement for in vitro 99mTc labelling of Erythrocytes

  • Mr Mohamed Abushhiwa, Faculty of Veterinary science, The University of Melbourne, Werribee, Victoria 3030, Australia, Australia
  • Mr Greg Wilton, Department of Nuclear Medicine, the Royal Melbourne Hospital, Parkville, Victoria 3052, Australia, Australia
  • Ms Dimitria Papadopoulos, Department of Nuclear Medicine, the Royal Melbourne Hospital, Parkville, Victoria 3052, Australia, Australia
  • Ms Karina Rodset, Department of Nuclear Medicine, the Royal Melbourne Hospital, Parkville, Victoria 3052, Australia, Australia
  • Ms Ingrid Wallner, Department of Nuclear Medicine, the Royal Melbourne Hospital, Parkville, Victoria 3052, Australia, Australia
  • Dr Meir Lichtenstein, Department of Nuclear Medicine, the Royal Melbourne Hospital, Parkville, Victoria 3052, Australia, Australia
  • Dr Nouria Salehi, Department of Nuclear Medicine, the Royal Melbourne Hospital, Parkville, Victoria 3052, Australia, Australia

    • Aim: To determine the ideal concentration of Sn(II) Ion to reduce 99mTc for in-vitro radiolabelling of erythrocytes in CGBP imaging. The method should be cost-effective and readily available alternative to the in-vivo radiolabelling of erythrocytes.

    Materials and Methods: 20mLs blood collected from four volunteers into sterile syringes containing 10IU of heparin. Each sample was divided into 2mls, (total of 40 samples). Concentrations of 1, 5, 10, 20 and 50µg /100µl of Sn(II) ion from stannous pyrophosphate kits was added (8 samples of each), mixed and incubated for 15mins at room temperature (RT). The samples were divided into 2 groups: Half were pre-washed with 2mls of 0.9% NaCl2(A) and half were un-washed(B). To each sample 800MBq of 99mTc was added, incubated for 20mins at RT and centrifuged for 5mins at 2000rpm. The supernatant was removed and labelling efficiency (LE) determined by measuring the supernatant and sediments. Each sediment was resuspended in 1ml normal saline and incubated for 2hrs at RT. The samples were centrifuged at 2000rpm for 5min and in-vitro labelling stability estimated.

    Results: The highest LE was obtained with 1µg/100µl concentration of Sn(II) ion.
    LE in group A was 97.50 % (ranging 95-99), ± 2.6 and group B was 88.9 % (ranging 88-90) ± 1.9. The red-cell labelling retention in all samples after 2hr incubation post-labelling was 95-97%.

    Conclusion: In-vitro radiolabelling of human erythrocytes using 1µg/100µl of Sn(II) Ion is an effective, simple, safe and cost-effective alternative to in-vivtro radiolabelling when the kit for the latter technique isn’t available.