Theoretical study of MRI metal artifacts by dental alloy

- Three dimensional analyses -

H.Samejima1, Y. Tegawa2, Y. Kinouchi3, and M. Akutagawa3

1 Graduate School of Advanced Technology and Science, The University of Tokushima,

2 Institute of Health Sciences, Graduate School, The University of Tokushima,

3 Institute of Technology and Science, Graduate School, The University of Tokushima

Abstract

 

The purpose of this study is to propose a method to calculate the metal artifact of MRI by dental alloys. The finite element method (FEM) is used widely used to calculate the magnetic field surrounding magnetic materials. Although the results by FEM fit to practical conditions, it is necessary to involve amount of time for preparation and calculation. If we have convenient, alternative, fundamental studies of MRI metal artifact expected to become simple.

In this study, a magnetic dipole is used as a substitution of a finite element method. A small magnetic material in the magnetic field, such as a magnetic keeper in MRI equipment, can be assumed as a magnetic dipole.

This analysis is for the understanding of the phenomenon and for the quantitative evaluation by spin echo sequence.

The MRI artifact by dental alloy contains distortion geometric and intensity distortion.

Intensity distortion is caused a decrease and an increase in the signal strength of NMR.

Distortion geometric is an error of the position information of the signal.

The result of this study shows a similar tendency as clinical studies, and it confirms that the analysis to approximate is possible.

Examination in different MRI sequence is future work.