Score based assessment of implant-related post fusion MRI artifacts focused on different interbody disc spacers: An in vitro study

Thorsten Ernstberger, Gabert Heidrich, Hans-Michael Klinger, Mike Herbert Baums

Center of Radiology Weilheim, Ambulatory Healthcare Center, Weilheim, Germany.
Clinic for Spinal Surgery, Klinikum Bad Bramstedt, Bad Bramstedt, Germany.
Department of Orthopaedic Surgery Friedrichsheim, University of Frankfurt, Frankfurt, Germany.
Department of Orthopaedic Surgery, University of Gottingen, Gottingen, Germany.

DOI: 10.4236/ojcd.2012.22005                

Abstract

Interbody disc spacers for anterior spine fusion are made of different materials, such as titanium alloys or carbon fiber reinforced polymers (CFRP). Implant-related susceptibility artifacts can decrease the quality of MRI scans. This cadaveric study aimed to demonstrate the extent that implant-related MRI artifacting affects the post fusion differentiation of the spinal canal (SC) and intervertebral disc space (IDS). In 6 cadaveric porcine spines, we evaluated the post-im- plantation MRI scans of a titanium and CFRP spacer that differed in shape and surface qualities. A spacer made of human cortical bone was used as a control. A defined evaluation unit was divided into regions of interest (ROI) to characterize the SC and IDS. Considering 15 different MRI sequences read independently by an interobserver-validated team of specialists artifact-affected image quality of the median MRI slice was rated on a modified score of 0-1-2-3. A maximum score of 15 points for the SC and 9 points for the IDS (100%) was possible. Turbo spin echo sequences produced the best scores for both spacers and the control. Only the control achieved a score of 100%. For the IDS the titanium and CFRP spacer maximally scored 0% and 74%, for the SC 80% and 99%, respectively. By using favored T1 TSE sequences the CFRP-spacer represented clear advantages in post fusion spinal imaging. Independent of artifact dimensions the used scoring system allowed us to create an implant-related ranking of MRI scan quality in reference to the bone control.

Keywords

Interbody Disc Spacer; Post Fusion MRI; Imaging Artifacts; Artifact Score

Conflicts of Interest

The authors declare no conflicts of interest.

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