Figure 15c. Misregistration due to physiologic activity in a 57-year-old woman with a history of moderately differentiated ovarian carcinoma with serous and endometrioid features (same patient as in Fig 6). (a) PET scan shows increased uptake in the left side of the abdomen (arrow). (b) CT scan shows a small peritoneal implant in the left paracolic gutter (arrow). (c) Fused PET-CT scan shows activity superimposed on the stomach (arrow) and just medial to the actual location of the implant (arrowhead). The misregistration is due to peristalsis or respiratory motion. Activity in the right kidney is normal.