LOOSENING OF ENDOPROSTHESIS EXAMINED WITH MONOENERGETIC DUAL ENERGY CT

Introduction Computer Tomography (CT) imaging has been limited to beam hardening artefacts until now. Literature has failed to describe sensitivity and specifity for loosening of endoprothesis in CTs, as metal artefacts have always influenced the diagnostic value of CTs. In recent years a new technology has been developed, the Dual Energy CT. Dual Energy CT scanners simultaneously scan with two tubes at different energy levels, most commonly 100kVp and 140kVp. Furthermore pictures gained from Dual Energy CTs are post-processed with monoenergetic reconstruction, which increases picture quality while further reducing metal artefacts. This promising technology has increased the diagnostic value preventing more radiation for the patients, for example in detection of kidney stones or to map lung perfusion. In the musculoskeletal imaging it has not been established yet and further clinical investigations are necessary. Thus the aim of this study is to describe sensitivity and sensibility for endoprothesis loosening of this novel technology. Material and Methods 53 prospective patients (31 total hip- and 22 total knee-arthoplasties) who were planned for revision surgery underwent preoperative Dual Energy CT examination. All scans were performed with a second-generation, dual-energy multi-detector CT scanner. And all pictures were post-processed with monoenergetic reconstruction. Radiologists were blinded for patient´s history. Senior consultants, who are specialized in arthroplasty of the hip and the knee, performed surgery. Intraoperative information was used as gold standard. Results We pressent the results of the current status of our study. In total hip athroplasty Dual Energy CTs showed a high sensitivity and specifity for cup loosening as well as shaft loosening. In total knee arthroplasty, sensitivity and specifity for the femoral and tibial component also showed high results. Conclusion Dual Energy CTs provide high sensitivity and specifity for detection of loosening of endoprosthesis. This novel technology has made it possible for the first time to overcome the problem with metal artefacts in CT imaging in the assessment of endoprosthesis. Furthermore, Dual Energy CTs offer a new diagnostic manner for endoprothesis in the future.