Descamps, Benedicte

Keereman, Vincent

Raedt, Robrecht

van Mierlo, Pieter

Vandenberghe, Stefaan

Vanhove, Christian

English

Ghent University Academic Bibliography

Continuous infusion PET with constant input functionVincent Keereman, Pieter van Mierlo, Benedicte Descamps,Stefaan Vandenberghe, Robrecht Raedt, Christian VanhoveJanuary 2, 2013INTRODUCTION Dynamic PET imaging can be used to study the pharmacoki-netic behaviour of administered radiotracers. This requires knowledge of the arterialblood concentration of the radiotracer, usually determined using blood sampling. How-ever, this is a cumbersome procedure, especially in small animal experiments. We havedeveloped a method which yields a constant arterial blood concentration of radiotracer,thereby rendering the use of arterial blood sampling unnecessary.MATERIALS AND METHODS The method was developed for 18F-FDG PETimaging of rats. First a bolus injection of 300 uCi of radiotracer is performed over 1min. Continuous infusion of radiotracer is then started. The infusion rate is adjustedcontinuously so that during each unit of time the amount of infused radiotracer is equalto the amount of radiotracer that has decayed inside the animal. In stable physiologicalconditions, a steady state with constant blood concentration will be reached after a timeinterval. We tested our method on 3 control rats. A PET acquisition of 3 hours wasperformed and reconstructed in 10 min frames. The average reconstructed PET valueinside a VOI on the cerebral cortex was calculated. Arterial blood samples were takenevery second and the average arterial blood radioactivity concentration was calculatedin each frame. The coefficient of variation (CoV) of the reconstructed PET value andarterial blood concentration was calculated over all frames after steady state was reached.To demonstrate a possible application of our method it was used to visualize the effectof intrahippocampal kainic acid (KA) injection (a model for epileptogenesis) on cerebralglucose metabolism in 1 rat’.RESULTS In all animals steady state was reached after less than 60 min. CoV ofthe arterial blood concentration between 60 and 180 minutes was approximately 10%in all controls. CoV of the average reconstructed PET value was approximately 5%. Inall controls no clear upward or downward trend was observed. In KA animals a strongincrease of glucose uptake was observed in the ipsilateral hippocampus after injectionof KA.CONCLUSION We have demonstrated the feasibility of using continuous infusionof radiotracer to obtain a constant arterial input function. This method allows dynamicPET imaging with knowledge of the arterial input function without the need for arterialblood sampling. Dynamic imaging of the effect of intrahippocampal KA injection wasdemonstrated as an application.FigureFigure 1: Arterial blood radioactivity concentration and reconstructed PET value in 3control rats as well as reconstructed PET value in the right and left hippocampus of a ratin which injection of kainic acid into the right hippocampus was performed at 80 min.

Continuous infusion PET with constant input function

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Continuous infusion PET with constant input function

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Ghent University Academic Bibliography