CT and MRI Techniques for Imaging Around Orthopedic Hardware

Abstract

ZUSAMMENFASSUNGOrthopädische Implantate verringern die Bildqualität in der Schnittbildgebung. Bei steigendem Einsatz von orthopädi-schen Implantaten in einer alternden Bevölkerung ist eine Metallartefaktreduktion von zunehmender Bedeutung. Im folgenden Review möchten wir einen Überblick über die wesentlichen Artefakte in der Computertomografie und Magnetresonanztomografie sowie die neuesten Standards zur Verbesserung der Bildqualität geben. Alle Schritte der Bildakquisition von Gerätewahl über Scanvorbereitungen und -parameter bis hin zur Bildverarbeitung beeinflussen das Ausmaß der Metallartefakte. Technische Fortschritte wie die Dual-energy-Computertomografie mit der Option der Virtuellen monochromatischen Bildgebung sowie neue Implantatmaterialien bieten weitere Möglichkeiten der Metallartefaktreduktion in CT und MRT. Dezidierte MetallartefaktSequenzen beinhalten Algorithmen zur Artefaktreduktion und zur Verbesserung der Bildqualität des umgebenden Gewebes und sind essenzielle Werkzeuge in der orthopä-dischen Bildgebung zur frühzeitigen Detektion von postoperativen Komplikationen. ABSTR AC TOrthopedic hardware impairs image quality in cross-sectional imaging. With an increasing number of orthopedic implants in an aging population, the need to mitigate metal artifacts in computed tomography and magnetic resonance imaging is becoming increasingly relevant. This review provides an overview of the major artifacts in CT and MRI and state-ofthe-art solutions to improve image quality. All steps of image acquisition from device selection, scan preparations and parameters to image post-processing influence the magnitude of metal artifacts. Technological advances like dual-energy CT with the possibility of virtual monochromatic imaging (VMI) and new materials offer opportunities to further reduce artifacts in CT and MRI. Dedicated metal artifact reduction sequences contain algorithms to reduce artifacts and improve imaging of surrounding tissue and are essential tools in orthopedic imaging to detect postoperative complications in early stages.

The value of iterative metal artifact reduction algorithms during antenna positioning for CT-guided microwave ablation

“…As a drawback of iMAR, the occurrence of new artifacts must be considered. Different studies have addressed this phenomenon, and the final conclusions were quite consistent: because the advantages of iMAR outweigh its disadvantages resulting in better visualization of anatomy and better conspicuity of anatomical abnormalities, the algorithm is ready for implementation in the clinical workflow [5,17,18,31]. It is worth noting that in this study, the new artifacts were not observed at the antenna tip or in the liver in extension of the antenna in the puncture direction, in other words, in the region of greatest interest.…”

Value of standard radiographs, computed tomography, and magnetic resonance imaging of the lumbar spine in detection of intraoperatively confirmed pedicle screw loosening—a prospective clinical trial

“…Therefore, we investigated in this study TSE with high bandwidth optimization and STIR WARP sequences which are known to have reasonable acquisition times. However, it remains unknown if sensitivity and specificity of MRI for detecting screw loosening would be improved using sequences with more acquisition time such as SEMAC or MAVRIC [20,22,23,25,34].…”

In vitro and in vivo study on the osseointegration of BCP‐coated versus uncoated nondegradable thermoplastic polyurethane focal knee resurfacing implants

“…Biomaterial advancements have led to the development of a hybrid implant comprised of a titanium base and a polymer top layer with an elastic modulus much more similar to the modulus of cartilage (Nathwani et al, 2017). However, the metal base still leads to scattering on computed tomography (CT) and magnetic resonance imaging (MRI) (Do, Sutter, Skornitzke, & Weber, 2018). Future clinical decision making is thus impaired, which is of great concern in case of new traumatic knee injuries (Adelani et al, 2016) and routine clinical follow‐up of the knee joint.…”