Modelling the tracer kinetics of [18F]-Fluor-Ethyl-Tyrosine (FET)

The kinetic analysis of FET uptake provides information on tumour grade in cerebral gliomas. High-grade gliomas, classified according to of the World Health Organization 2007 (WHO 2007) as grades III or IV, are characterised by an early peak around 10–15 min after injection followed by a decrease of FET uptake. In contrast, time-activity curves in low-grade diffuse gliomas, classified as grade II, increase slightly and steadily. Previous methods suggested by other groups evaluated the kinetics of the entire tumour or just the spot of maximum uptake. In contrast, we have developed a simple method to generate parametric images of FET kinetics by fitting the time-activity curves in each voxel by linear regression lines. The use of this method makes a detailed analysis within the entire tumour area possible. Further research is underway to improve the method by using empirical, non-linear models that are able to reproduce the time activity curves for all time frames of the dynamic PET image data.