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FIGURE 1. PET/CT precisely localizes suspected foci of abnormal 18F-FDG uptake for diagnosis and estimation of extent of recurrence. A 66-y-old man with colon cancer, stage C, after surgical removal of primary tumor, was assessed for recurrence suggested by elevated levels of CEA serum marker. Results of CT scan performed 2 wk before present examination were negative. (A) 18F-FDG PET study (coronal slices) demonstrates foci of abnormal 18F-FDG uptake in right and middle abdomen. (B) Transaxial slices at level of these findings show paramedian left and right abnormal 18F-FDG foci seen on PET (left), localized by PET/CT (center) to slightly enlarged para-aortic lymph nodes, as demonstrated on CT (right), consistent with metastatic lymphadenopathy. (Focus of increased 18F-FDG uptake in right abdomen is localized by PET/CT to physiologic bowel activity.) On basis of these findings, chemotherapy regimen was changed from adjuvant protocol to drug combination used for treatment of metastatic disease. At follow-up 5 mo later, tumor markers had returned to normal, and repeat PET/CT results were negative. Patient is being reevaluated for consideration of consolidation radiotherapy to area of involved lymph nodes.
