OBJECTIVE: To evaluate the artifact sizes at 3.0 T compared to at 1.5 T caused by three kinds of metallic dental materials, and to evaluate the influences of different magnetic resonance imaging (MRI) sequences on the artifact.METHODS: Samples of metal-ceramic crown of three kinds of dental materials (Ni-Cr alloy, Co-Cr alloy, and gold alloy) were placed in a cylindrical plastic vessel filled with agarose gel. Acrylic resin crown was used as control. Images were performed by means of 1.5 T and 3.0 T MRI apparatus with 4 different sequences commonly used in brain MRI sequences. Artifact diameter was calculated and compared quantitatively. A 4 x 4 x 2 factorial design was applied to determine the effects on the MRI artifact of different metal materials, different sequences, and different magnetic field strengths.RESULTS: ANOVA of factorial design showed that the influences of material, magnetic field strength, and sequence were all significantly different( materials: F = 124.796, df = 3, P = 0.000; magnetic field strength: F = 9.367, df = 1, P = 0.003; sequence: F = 3.020, df = 3, P = 0.036). Among the 3 kinds of alloys, the gold alloy produced the least artifact. Among the 4 imaging sequences, fast spin echo (FSE) produced the least artifact. The artifact sizes increased at 3.0 T compared to at 1.5T. Interactions among the 3 factors did not influence the artifacts significantly (P > 0.05).CONCLUSION: Selection of specific metal material and imaging sequence can minimize the metal artifacts in MRI. The increment of artifacts at 3.0 T is only by 10% compared to that at 1.5 T. But 3.0 T MRI system has great advantages, so it is eligible on patients with metal restoration.
Artifacts Dental Alloys