Quantitative dynamic ¹⁸FDG-PET and tracer kinetic analysis of soft tissue sarcomas

Abstract

Purpose. To study soft tissue sarcomas using dynamic positron emission tomography (PET) with the glucose analog tracer [¹⁸F]fluoro-2-deoxy-D-glucose (¹⁸FDG), to investigate correlations between derived PET image parameters and clinical characteristics, and to discuss implications of dynamic PET acquisition (D-PET). Material and methods. D-PET images of 11 patients with soft tissue sarcomas were analyzed voxel-by-voxel using a compartment tracer kinetic model providing estimates of transfer rates between the vascular, non-metabolized, and metabolized compartments. Furthermore, standard uptake values (SUVs) in the early (2 min p.i.; SUV_E) and late (45 min p.i.; SUV_L) phases of the PET acquisition were obtained. The derived transfer rates K₁, k₂ and k₃, along with the metabolic rate of ¹⁸FDG (MR_FDG) and the vascular fraction ν_p, was fused with the computed tomography (CT) images for visual interpretation. Correlations between D-PET imaging parameters and clinical parameters, i.e. tumor size, grade and clinical status, were calculated with a significance level of 0.05. Results. The temporal uptake pattern of ¹⁸FDG in the tumor varied considerably from patient to patient. SUV_E peak was higher than SUV_L peak for four patients. The images of the rate constants showed a systematic pattern, often with elevated intensity in the tumors compared to surrounding tissue. Significant correlations were found between SUV_E/L and some of the rate parameters. Conclusions. Dynamic ¹⁸FDG-PET may provide additional valuable information on soft tissue sarcomas not obtainable from conventional ¹⁸FDG-PET. The prognostic role of dynamic imaging should be investigated.

Acknowledgements

Dr. Trond Velde Bogsrud is gratefully acknowledged for contributing to the initiation of the project.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.