Extended-field CT-Technik zur Evaluation von periprothetischen Knochenläsionen - - In-vitro-Untersuchung - -

thetic bone lesions - an in vitro study. Purpose: In the present study the reduction of artifacts using an extended CT scale technique was examined in 5 vitallium and 5 titanium-aluminium-vanadium tumor prostheses. Methods: 5 titanium-aluminium-vanadium and 5 vitallium distal femur Mutars® tumor prostheses (Mutars® - Modular Universal Tumor And Revision System) were implanted in 10 human femur specimens. 110 artifical drill hole lesions of 1 mm, 2 mm, 3 mm, 5 mm and 8 mm diameter were placed in the bone around the hexagonal stem of the tumor prosthesis and furthermore in the proximal part of the femur. All specimens were examined using conventional CT and an extended CT scale technique in a slice thickness of 3 mm. Results: In the proximal part of the femur all drill holes could be detected using 3 mm slices, no artefacts were observed. Along the hexagonal stem smooth lines arising from each hexagonal plane could be observed. This made it impossible to detect a 1 mm drill in 1 vitallium and in 1 titanium-aluminium-vanadium stem. There was no difference between the extended CT scale and conventional CT. Conclusion: The extended CT scale did not significantly (p > 0.05, t-test) improve the imaging of artifical drill hole lesions along the hexagonal Mutras® stem.