Quantification aspects of patient studies with 52Fe in positron emission tomography

Quantification accuracy in positron emission tomography (PET) using non-pure positron emitters, such as 52Fe, may be influenced by gamma radiation emitted in the decay of these isotopes. High-energy positrons, emitted in the decay of the 52Fe-daughter 52mMn, also affect the quantification accuracy. A specific problem of the 52Fe/52mMn decay chain in vivo is that the kinetics of iron and manganese are different, and that PET cannot discriminate between the two nuclides. The effect of the decay properties of 52Fe/52mMn on the performance of PET was investigated using phantoms. Minor degradation in PET performance was found for 52Fe/52mMn compared to the pure low-energy positron emitter 18F. A method is presented to obtain a correction factor for the 52mMn radioactivity in blood. A model for correction of 52mMn-radioactivity in organs, based on existing data on manganese kinetics, is given. The presented corrections are discussed and illustrated in a patient study.