Metal-induced artifacts in computed tomography and magnetic resonance imaging: comparison of a biodegradable magnesium alloy versus titanium and stainless steel controls

Abstract

Objective: To evaluate metal artifacts induced by biodegradable magnesium—a new class of degradable biomaterial that is beginning to enter the orthopedic routine—on CT and MRI compared to standard titanium and steel controls. Methods: Different pins made of titanium, stainless steel, and biodegradable magnesium alloys were scanned using a second-generation dual-energy multidetector CT and a 1.5-T MR scanner. In CT, quantitative assessment of artifacts was performed by two independent readers by measuring the noise in standardized regions of interest close to the pins. In MRI, the artifact diameter was measured. Interobserver agreement was evaluated using intraclass correlation coefficients. Artifacts were compared using Mann Whitney U tests. Results: In comparison to stainless steel, biodegradable magnesium alloys induced significantly fewer artifacts in both 1.5-T MRI (p = 0.019–0.021) and CT (p = 0.003–0.006). Compared to titanium, magnesium induced significantly less artifact-related noise in CT (p = 0.003–0.008). Although artifacts were less on MRI for biodegradable magnesium compared to titanium, this result was not statistically significant. Conclusion: Biodegradable magnesium alloys induce substantially fewer artifacts in CT compared to standard titanium and stainless steel, and fewer artifacts in MRI for the comparison with stainless steel.