CT and Metal-Artifact Reduction in Orthopaedic Implants: Can Tin-Filter Technology Help?

Objectives: The aim of the study was to assess for image quality and dose with different orthopaedic implants while using different computed tomography (CT) modalities, especially dual-energy computed tomography (DECT) and tin-filter technology versus conventional CT, while reducing dose at the same time.

Methods: Four cadavers (pelvis und lower lumbar spine) with orthopaedic implants were tested, using nine different scan protocols. Full-dose (FD; CDTI 10 mGy) and low-dose (LD; CDTI 3.3 mGy) scans using the tin-filter technique, DECT, and conventional CT were performed with a third-generation DECT scanner. Evaluation was done with a six-part Likert scale for objective and subjective parameters.

Results: In all four cadavers, FD tin-filter scans showed the best overall results, with an average of 1.3 (FD 150 kV program: 1.72; LD 150 kV tin-filter program: 2.3; FD DECT program: 2.63). Looking only at metal-artifact reduction, the best results were obtained using the DECT technique (FD as well as LD), but these images suffered from high imaging noise that reduced their overall rating.

Conclusion: Tin-filter technology did effectively reduce metal artifacts while providing good image quality of the adjacent bony structures near orthopaedic implants. Although DECT showed the best metal-artifact reduction, it suffered from image noise that obscured fine bony structures. Using an LD 150 kV tin-filter program can significantly reduce dose (to a third of the normal dose) while still providing good image quality and good metal-artifact reduction.

Conflict of Interest: None declared.

No conflict of interest has been declared by the author(s).