| 1237 Magnetic Susceptibility of Dental Alloys in Relation to Metal Artifacts in MR Imaging | ||
|
F. SHAFIEI, E. HONDA, H. TAKAHASHI, and T. SASAKI, TOKYO MEDICAL AND DENTAL UNIVERSITY, Tokyo, Japan Objectives: To determine the relationship between magnetic susceptibility of dental alloys and magnitude of metal artifacts in MR imaging. Methods: Ten commercially available dental casting alloys including gold, titanium and palladium alloys differing in their composition were selected. All dental alloys were casted in cubic shape with an edge of 5mm according to manufacturers' instruction. An acrylic resin block was employed as a control. A cylindrical shape phantom with a resin post inside for placing sample was made. Using MR imaging (1.5T, Magnetom Vision, Siemens) all casted alloys and resin block were imaged in gradient echo sequences (TE=18 ms, TR=500 ms). Signal intensities (SI) of the ROI (region of interest) in water, approximately 3,000 pixels around the images of samples in the phantom, were measured. Mean and standard deviation (SD) of water SI in the ROI was determined for the homogeneity around the dental alloys and resin block in gradient echo sequences. Magnetic susceptibility of all ten alloys and resin block, defined as the ratio of the net induced magnetic intensity to that of applied magnetic field, was measured at the room temperature under the magnetic field of 1.5T with the SQUID (Superconducting Quantum Interference Device) equipment (Quantum Design) Results: Mean and SD of ROI (10cm2) with magnetic susceptibility of the alloys and resin ranged from -0.008 to +0.135 were evaluated. The correlation between magnetic susceptibility and standard deviation that represents the heterogeneity of SI in the ROI was highly significant. A correlation between mean and coefficient of variation was also highly significant with r=0.971 (p<0.001) Conclusion: Magnitude of metal artifact is significantly related to the magnetic susceptibility of alloy. We concluded that with the measurement of the magnetic susceptibility of alloy we could predict the magnitude of dental alloys artifacts in magnetic resonance imaging. Alloys with negative magnetic susceptibility have much less artifacts than those with positive magnetic susceptibility.
| ||
| Seq #121 - Casting Alloys I 3:45 PM-5:00 PM, Thursday, 7 March 2002 San Diego Convention Center Exhibit Hall C | ||
|
Back to the Dental Materials: VII - Others-Metallic Program
| ||