Comparison of Metal Artifact Reduction for Orthopedic Implants versus Standard Filtered Back Projection: Value of Postoperative CT after Hip Replacement

Abstract

Purpose: To evaluate Metal Artifact Reduction for Orthopedic Implants (O-MAR, Philips Healthcare) technique compared with standard filtered back projection (SFBP) technique on post-operative hip CT regarding image noise reduction and detection of post-operative complications. Materials and Methods: Fifty-six hip CT scans after hip replacement with SFBP technique and O-MAR application were retrospectively reviewed. Region of interests (ROIs) were drawn at levels wherein acetabular cup and femoral head were largest at anterior and posterior acetabula, gluteus maximus muscle, subcutaneous fat adjacent to gluteus maximus muscle, and in area adjacent to prosthesis stem wherein lesser trochanter is largest. Hounsfield units (HU) were measured to evaluate artifact quantitatively; mean and standard deviations (SDs) calculated and compared. Periprosthetic complications were evaluated, and visibility rated between two reconstruction techniques; 1-SFBP better, 2–SFBP same as O-MAR, 3–O-MAR better. Results: Average HU was significantly lower in O-MAR at posterior acetabulum, gluteus maximus muscle, and subcutaneous fat (p < 0.05). SD for HU was significantly lower in O-MAR at all ROIs (p < 0.05). Mean visibility of periprosthetic complications was 2.0, so equivalent. Conclusion: Reconstruction with O-MAR technique in post-operative hip CT scans after hip replacement yielded statistically significant decrease in image noise. However, visibility of periprosthetic complications was not impacted by reconstruction technique.

Keywords

• tomography
• x-ray computed
• metals
• artifacts
• prosthesis
• hip