FIGURE 6.  ¹⁸F-FDG and ¹⁸F scans of metastatic colon cancer fused to same "isoaligned" CT scan. (A) Large lesions dominating right lobe of liver. (B) Faint tracer uptake (arrow) in right upper quadrant in otherwise negative PET bone scan. (C) Transaxial CT slice of larger lesion showing calcifications in tumor. (D) Prospective fusion of ¹⁸F-FDG PET and CT showing peripheral hypermetabolic margin of tumor with decreased metabolism in center of mass. (E) Retrospective fusion of ¹⁸F-FDG PET and previous CT delineating extent of tumor calcifications and central necrosis.