Abstract for presentation at 38th Annual Scientific Meeting of the Australian and New Zealand Society of Nuclear Medicine 2008

In patients with difficult venous access presenting for radionuclide scans, long-line cannulas may occasionally be used as an intravenous port of last resort for administration of radionuclide tracer. Binding of tracer to the cannula can compromise the quality of subsequent imaging. We set out to determine if preloading long-line cannulas with 'cold' tracer would reduce the amount of activity bound after a subsequent dose of radio-labelled tracer.
Methods:
Two experiments were performed:
1. Four long-line cannulas were obtained and loaded with different concentrations of Glucose ranging from 5% to 50%. The cannulas were subsequently flushed with F18FDG Glucose which was left in-situ for 60 seconds. Subsequently the cannulas were flushed with saline and the cannula residual activity measured using a Capintec well counter.
2. Four long-line cannulas were obtained and loaded with a standard concentration of 'cold' MDP. The cannulas were subsequently flushed with Tc^99mMDP which was in left situ for times varying from one to 10 minutes. Subsequently the cannulas were flushed with saline and the cannula residual activity measured using a Gamma Camera and the well counter.
Results: There was significantly lower activity in the cannulas preloaded with 'cold' tracer compared to controls. The reduction in activity bound by the cannulas exceeded 20%. Further experiments are continuing to determine whether the activity bound could be decreased further using different protocols.
Conclusion: Preloading a long-line cannula with 'cold' tracer potentially may reduce the amount of activity bound after a subsequent dose of radio-labelled tracer.