FIGURE 4. Precise anatomic localization of malignant ¹⁸F-FDG uptake and retrospective lesion detection on CT, after PET/CT. A 33-y-old man with Hodgkin’s disease in left cervical region was referred for ¹⁸F-FDG PET for staging. No other sites of disease were reported on CT. (A) PET images show infradiaphragmatic focus of abnormal ¹⁸F-FDG uptake in medial border of liver, consistent with either liver involvement (stage IV disease?) or nodal disease in porta hepatis (stage III disease?). (B) Hybrid PET/CT axial image (top) precisely localizes ¹⁸F-FDG uptake to adenopathy at porta hepatis, only retrospectively detected on corresponding CT image (bottom) (arrow). Patient was treated as having stage III disease and achieved complete response, showing no evidence of disease for follow-up of 12 mo.