Induced magnetic moment in stainless steel components of orthodontic appliances in 1.5 T MRI scanners

Zhiyue J. Wang, Nancy K. Rollins, Hui Liang, Yong Jong Park

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Purpose: Most orthodontic appliances are made of stainless steel materials and induce severe magnetic susceptibility artifacts in brain MRI. In an effort for correcting these artifacts, it is important to know the value of induced magnetic moments in all parts of orthodontic appliances. In this study, the induced magnetic moment of stainless steel orthodontic brackets, molar bands, and arch-wires from several vendors is measured. Methods: Individual stainless steel brackets, molar bands, and short segments of arch-wire were positioned in the center of spherical flask filled with water through a thin plastic rod. The induced magnetic moment at 1.5 T was determined by fitting the B0 map to the z-component of the magnetic dipole field using a computer routine. Results: The induced magnetic moment at 1.5 T was dominated by the longitudinal component mz, with a small contribution from the transverse components. The mz was insensitive to the orientation of the metal parts. The orthodontic brackets collectively dom nated the magnetic dipole moment in orthodontic appliances. In brackets from six vendors, the total induced mz from 20 brackets for nonmolar teeth ranged from 0.108 to 0.158 (median 0.122) Am2. The mz in eight molar bands with bracket attachment from two vendors ranged from 0.0004 to 0.0166 (median 0.0035) Am2. Several full length arch wires had induced magnetic moment in the range of 0.0060.025 (median 0.015) Am2. Conclusions: Orthodontic brackets collectively contributed most to the total magnetic moment. Different types of brackets, molar bands, and arch wires all exhibit substantial variability in the induced magnetic moment.

Original languageEnglish (US)
Pages (from-to)5871-5878
Number of pages8
JournalMedical Physics
Volume42
Issue number10
DOIs
StatePublished - Oct 1 2015

Fingerprint

Orthodontic Brackets
Orthodontic Appliances
Stainless Steel
Artifacts
Magnetic Fields
Plastics
Tooth
Metals
Water
Brain

Keywords

  • induced magnetic moment
  • MRI artifacts
  • orthodontic appliances
  • stainless steel

ASJC Scopus subject areas

  • Biophysics
  • Radiology Nuclear Medicine and imaging

Cite this

Induced magnetic moment in stainless steel components of orthodontic appliances in 1.5 T MRI scanners. / Wang, Zhiyue J.; Rollins, Nancy K.; Liang, Hui; Park, Yong Jong.

In: Medical Physics, Vol. 42, No. 10, 01.10.2015, p. 5871-5878.

Research output: Contribution to journalArticle

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