5种常用口腔材料的磁共振伪影比较

Comparison of magnetic resonance imaging artifacts of five common dental materials

目的比较口腔科常用的3种金属和2种陶瓷材料在0.35、1.5及3 T 3种场强磁共振成像(MRI)不同序列中形成伪影的差异。方法将3种金属和2种陶瓷材料制作成同样大小及厚度的中切牙内冠,将其置入盛满生理盐水的塑料罐体中,分别在0.35、1.5和3.0 T的磁共振(MR)机中扫描获得T1WI、T2WI影像。比较各种材料在不同场强的MR扫描中伪影的差异。结果氧化锆在3种场强的MR机中扫描无明显伪影;铸造陶瓷伪影极轻微;贵金属合金、烤瓷镍铬合金与烤瓷钴铬合金在3种场强MR扫描中均出现不同程度的伪影。结论氧化锆、铸造陶瓷这两种常用口腔陶瓷材料基本无伪影或伪影极轻微。贵金属合金、烤瓷镍铬合金与烤瓷钴铬合金3种常用口腔金属材料易引起MRI伪影,且随着主磁体场强增加,伪影面积增大。

Objective To compare five materials commonly used in dentistry, including three types of metals and two types of ceramics, by using different sequences of three magnetic resonance imaging （MRI） field strengths （0.35, 1.5, and 3.0 T）. Methods Three types of metals and two types of ceramics that were fabricated into the same size and thickness as an incisor crown were placed in a plastic tank filled with saline. The crowns were scanned using an magnetic resonance （MR） machine at 0.35, 1.5, and 3.0 T field strengths. The T1WI and T2WI images were obtained. The differences of various materials in different artifacts of field MR scans were determined. Results The zirconia crown presented no significant artifacts when scanned under the three types of MRI field strengths. The artifacts of casting ceramic were minimal. All dental precious metal alloys, nickel-chromium alloy dental porcelain, and cobalt-chromium ceramic alloy showed varying degrees of artifacts under the three MRI field strengths. Conclusion Zirconia and casting ceramics present almost no or faint artifacts. By contrast, precious metal alloys, nickel-chromium alloy dental porcelain and cobalt-chromium ceramic alloy display MRI artifacts. The artifact area increase with increasing magnetic field.