Impact of contamination with long-lived radionuclides on PET kinetics modelling in multitracer studies
Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
Introduction: An important issue in multitracer studies is the separation of signals from the different radiotracers. This is especially the case when an early tracer has a long physical half-life and kinetic modelling has to be performed, because the early tracer can confer a long-lived contaminating background not only to images but also to a measured input function derived from blood samples. In this study, we examined data from a sequential multitracer infection study involving 111In (t1/2=2.8 days), investigating the influence on gamma counting of blood samples and on the kinetic modelling of subsequent PET tracers. Blood sample counts were corrected by recounting the samples a few days later. A more optimal choice of energy window was also explored. The effect of correction versus noncorrection was investigated using a two-tissue kinetic model with irreversible uptake (K1, k2, k3).
Results: K1 was least affected and k3 was most affected by the contamination, corresponding to the effect being relatively larger on the late part of the blood input function. A narrower energy window reduced the problem, but this will not be possible for all types of contaminating background.
Conclusion: Gamma counting of blood samples can lead to a contaminating background not observed in PET imaging and this background can affect kinetic modelling. If the contaminating tracer has a much longer half-life than the foreground tracer, then the problem can be solved by late recounting of the samples.
Results: K1 was least affected and k3 was most affected by the contamination, corresponding to the effect being relatively larger on the late part of the blood input function. A narrower energy window reduced the problem, but this will not be possible for all types of contaminating background.
Conclusion: Gamma counting of blood samples can lead to a contaminating background not observed in PET imaging and this background can affect kinetic modelling. If the contaminating tracer has a much longer half-life than the foreground tracer, then the problem can be solved by late recounting of the samples.
Originalsprog | Engelsk |
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Tidsskrift | Nuclear Medicine Communications |
Vol/bind | 37 |
Udgave nummer | 8 |
Sider (fra-til) | 818-824 |
Antal sider | 7 |
ISSN | 0143-3636 |
DOI | |
Status | Udgivet - aug. 2016 |
ID: 165393142