The tracer used in PET is 18F-fluoro-2-deoxy-d-glucose. Generally cancer cells are thought to have low or absent G6Pase expression compared to normal cells and cancer cells have increased expression of GLUT (especially GLUT1) and hexokinase (especially HK2), which further leads to intracellular trapping of FDG-6-phosphate in malignant cells and there by yielding high maximum standardized uptake value (SUVmax). But ovarian cancers have found to have a relatively low ratio of hexokinase/phosphatase maybe explaining the low/absent rise in FDG-uptake. The amounts of GLUT, hexokinase and G6Pase are responsible for the FDG trapping intracellular and the retention on the late scans.