Parametric PET of Genitourinary Cancer

Whole-body 18F- fluorodeoxyglucose (FDG) PET is widely used for metabolic imaging in clinical oncology. However, FDG-PET has been rarely used for imaging genitourinary cancer  (GUC, e.g., renal cell carcinoma, urothelial bladder carcinoma) because physiological excretion of FDG into the urinary system contaminates image quality for primary GUC evaluation (Fig. 1A).

We are developing a parametric PET solution to this problem to further push the applicability of FDG-PET in clinical oncology.  Standard clinical use of FDG-PET acquires a static three-dimensional image of FDG uptake at a late time point (commonly one-hour post injection) and the image quality suffers from urinary excretion. In comparison, the parametric PET method employs dynamic scanning to capture both 3D spatial and 1D temporal distributions of the early-phase of FDG uptake in the genitourinary system. While the late-time uptake image by standard FDG-PET is commonly contaminated by FDG excretion, the early-time phase data of dynamic PET are much less affected. Figure 1B shows an example of better visualization of renal cortex by the parametric PET method.

While standard FDG-PET characterizes steady-state glucose metabolism, our parametric PET method extract the information of glucose transport. The method would have to be restricted to either primary GUC or metastasis if a conventional PET scanner of limited field-of-view (~20cm) is used. The advent of 2-meter total-body PET scanner EXPLORER allows the parametric evaluation for both primary GUC and distant metastases. We are conducting a pilot clinical trial to explore the potential of this parametric PET technique for early therapeutic response assessment in targeted therapy and immunotherapy of GUC.

The pilot research of this project is supported by a UC Cancer Research Coordinating Committee Award and also supported by a NIH K12 Scholar Award in the UC Davis Comprehensive Cancer Center.