• Michael J Gelfand and Susan E Sharp.
• Department of Radiology, Nuclear Medicine Division, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave., Cincinnati, OH, 45229-3026, USA, michael.gelfand@cchmc.org.
• Pediatr Radiol. 2015 Jul 1; 45 (8): 1182-8.

BackgroundMetal endoprostheses and internal fixation devices cause significant artifacts on CT after limb salvage surgery; positron emission tomography (PET) images should be evaluated for artifacts.Objective(1) To describe [F-18]2-fluoro-2-deoxyglucose (FDG) PET uptake patterns after limb salvage surgery. (2) To determine whether metal endoprostheses and fixation hardware cause significant artifacts on CT attenuation-corrected PET that interfere with diagnostic use of PET/CT after limb salvage surgery.Materials And MethodsWe reviewed 92 studies from 18 patients ages 5-21 years. Diagnoses were osteogenic sarcoma in 14, Ewing sarcoma in 3, and malignant peripheral nerve sheath tumor originating in bone in 1. Nine patients had distal femur/knee endoprostheses, five had lower-extremity bone allografts secured by large metal plates and four had upper-extremity limb salvage procedures. Maximum standardized uptake value was calculated at lower-extremity soft-tissue-endoprosthesis interfaces. In 15 patients with PET/CT imaging, the first PET/CT scan after limb salvage surgery was reviewed for metal artifacts on CT images and for artifacts at locations on PET corresponding to the CT metal artifacts.ResultsIncreased FDG uptake was consistently present at soft-tissue interfaces with endoprostheses, allografts and internal fixation devices, with little or no FDG uptake at cemented endoprosthesis-bone interfaces. Maximum standardized uptake value at margins of femur/knee endoprostheses ranged from 1.4 to 5.7. In four patients with distal femur/knee endoprostheses, minimal artifact was noted on attenuation-corrected PET images, but image interpretation was not affected. In the other 11 patients who had CT attenuation correction, we detected no artifacts caused by the attenuation correction.ConclusionCT attenuation correction did not cause artifacts that affected interpretation of attenuation-corrected PET images.

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