Influence of Metal Artifact by Orthodontic Appliances on Brain MRI

The purpose of this study was to evaluate brain MRI distortion caused by orthodontic appliances. MRI was performed in 10 subjects and after insertion 3 kind of orthodontic appliances(type1-3), the MRI were compared. Type 1 used resin brackets in the incisor teeth, stainless steel brackets in the premolar teeth and stainless steel single tube in the molar teeth. Type2 used ceramic brackets in the incisor teeth, titanium brackets in the premolar teeth and titanium single tube in the molar teeth. Type3 used ceramic brackets with CoCr alloy clip in the incisor teeth, titanium brackets in the premolar teeth and titanium single tube in the molar teeth. Each MR sequence consisted of 6 sequences.: the Echo Planar Imaging method diffusion-weighted images(DWI), Spin Echo sequence(SE)T1-weighted images, Fast Field Echo sequence(FFE)T1-weighted images, Turbo Spin echo sequence(TSE)T2-weighted images, fat-supression image as Short Tau inversion recovery method(STIR), and Fluid attenuated-inversion recovery(FLAIR).Two neurosurgeons examined the MRI for distortion in predetermined regions of the brain. In Type 1, MRI imaging by neither DWI nor FFE is feasible in these sites. SE-T1, TSE-T2, FLAIR and STIR are indicating the feasibility for MRI imaging. In Type 2 and Type 3, by all imaging types and at all of the anatomical sites, are indicating the feasibility for MRI imaging in the brain. The study showed that ceramic brackets, ceramic brackets with CoCr alloy clip, titanium brackets and titanium tubes do not always have to be removed before brain MRI.