Respiratory Artefact Causing Malpositioning of Liver Dome Lesion in Right Lower Lung

The new combined positron emission (PET)/computed tomographic (CT) scanners have many advantages over PET scanners alone. However, physicians must be aware of the potential artefacts observed in PET/CT scanners. A body PET/CT was performed on an 81-year-old man with colorectal cancer. The CT-based, attenuation-corrected PET image showed a right lower lung lesion. However, there was no lung lesion on the transmission CT image. Nonattenuation-corrected PET, and rod source-based, attenuation-corrected PET images demonstrated focal uptake in the dome of the liver. Dedicated CT with intravenous contrast confirmed that the lesion was in the liver dome and not in the right lower lung. The liver lesion was misplaced to the right lower lung in the CT-based, attenuation-corrected PET image because of a respiratory artefact. To overcome this respiration artefact the authors suggest a routine review of the nonattenuation-corrected PET images, particularly when evaluating liver dome and lower lung lesions.