AIM: Positioning of interventional devices in liver lesions is a challenging task if only CT is available. We investigated the potential benefit of combined PET/CT images for localization of interventional devices in interventional liver studies. METHODS: Thirty lesions each of hyperdense, isodense and hypodense attenuation compared to normal liver parenchyma were injected into 15 ex-vivo pig livers. All lesions were composed of the same amounts of gelatine containing 0.5 MBq of 18F-FDG. Following lesion insertion, an interventional needle was placed in each lesion under CT-guidance solely. After that, a PET/CT study was performed. The localization of the needle within the lesion was assessed for CT alone and PET/CT and the root mean square (RMS) was calculated. Results were compared with macroscopic measurements after lesion dissection serving as the standard of reference. RESULTS: In hypo- and isodense lesions PET/CT proved more accurate in defining the position of the interventional device when compared with CT alone. The mean RMS for CT and PET/CT differed significantly in isodense and hypodense lesions. No significant difference was found for hyperdense lesions. CONCLUSION: Combined FDG-PET/CT imaging provides more accurate information than CT alone concerning the needle position in FDG-PET positive liver lesions. Therefore combined PET/CT might be potentially beneficial not only for localization of an interventional device, but may also be beneficial for guidance in interventional liver procedures. AIM: Positioning of interventional devices in liver lesions is a challenging task if only CT is available. We investigated the potential benefit of combined PET / CT images for localization of interventional devices in interventional liver studies. METHODS: Thirty lesions each of hyperdense, isodense and All lesions were composed of the same amount of gelatine containing 0.5 MBq of 18F-FDG. Following lesion insertion, an interventional needle was placed in each lesion under CT- guidance than. After that, a PET / CT study was performed. The localization of the needle within the lesion was evaluated for CT alone and PET / CT and the root mean square (RMS) was calculated. Results were compared with macroscopic measurements after lesion dissection serving as the standard of reference. RESULTS: In hypo- and isodense lesions PET / CT proved more accurate in defining the position of the interventional device when compared with CT alone. The mean RMS for CT and PET / CT differed significantly in isodense and hypodense lesions. No significant difference was found for hyperdense lesions. CONCLUSION: Combined FDG-PET / CT imaging provides more accurate information than CT only concerning The combined position of PET / CT positive for lesions in an interventional device, but also for guidance in interventional liver procedures.