Evaluation of magnetic resonance imaging issues of titanium and stainless steel brackets

Magnetic resonance imaging (MRI) is a sophisticated diagnostic method of contemporary medicine. This examination in patients with metallic objects is often complicated due to MRI issues. Clinically significant difference in MRI issues of titanium (equilibrium ti, Dentaurum) and stainless steel (Gemini, 3M Unitec) brackets was studied in a clinical 1.5 T and an experimental 4.7 T MRI scanners. In this in vitro study, the following parameters were assessed: artefacts, magnetic field interaction, and heating. Artefacts were evaluated in spin and gradient echo images using ASTM F2119-07 standard in 1.5 T field. Translational attraction, torque and heating were tested. The titanium bracket for upper lateral incisor produced 2.5?4.3 mm and 4.7?4.9 mm artefacts in spin and gradient echo scans, respectively. The stainless steel bracket for upper lateral incisor caused more than 50 mm distortions in the same sequences. Images of the titanium bracket set were diagnostically acceptable whereas the stainless steel bracket set could not be graded due to the incapability of the MRI scanner to adjust resonance frequency. No clinically relevant translational attraction and no torque were detected for equilibrium ti brackets, while Gemini brackets were strongly attracted by the magnetic field. No clinically significant heating was observed. Noticeable difference in MRI issues of the brackets was observed in artefacts and mobility. Gemini brackets were found unacceptable for MRI.