Parametric imaging: a promising approach for the evaluation of dynamic PET-18F-FDG studies - the DKFZ experience.

Dynamic positron emission studies (dPET) with fluorine-18-fluoro-deoxyglucose ((18)F-FDG) were performed in oncologic patients. The primary aim was to evaluate the impact of parametric imaging and assess its feasibility with regard to diagnostics and treatment management. Parametric PET images based on different algorithms have been calculated. Regression-based images, influx images according to Patlak, two-tissue compartment images as well as non-compartmental approaches, based on the fractal dimension, principal component images, and similarity mapping have been used. Our results showed that the use of parametric images is helpful to visualize quantitative parameters of the tracer kinetics and adds a new dimension to the existing conventional PET or PET/computerized tomography (CT) images. Especially, non-compartment models are computationally fast and can be applied in daily routine to gain more detailed information about the distribution of a tracer over time and space. In conclusion, it is our opinion that parametric images will gain increasing importance and find their way into clinical routine due to the improvement of the technical equipment, like computer power, faster data acquisition by new generations of PET/CT scanners and more sophisticated software for data evaluation.