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MRI Susceptibility Artefacts Caused by Orthodontic Wires
abstract
This abstract is available on the publisher's site.
Access this abstract nowOBJECTIVES
To evaluate magnetic susceptibility artefacts produced by orthodontic wires on MRI and the influence of wire properties and MRI image sequences on the magnitude of the artefact.
METHODS
Arch form orthodontic wires [four stainless steels (SS), one cobalt chromium (CC) alloy, 13 titanium (Ti) alloys] were embedded in a polyester phantom, and scanned using a 1.5-T superconducting magnet scanner with an eight-channel phased-array coil. All wires were scanned with T1-weighted spin echo (SE) and gradient echo (GRE) sequences according to the American Society for Testing and Materials (ASTM) F2119-07 standard. The phantom was also scanned other eight sequences. Artefacts were measured using the ASTM F2119-07 definition and OsiriX software. Artefact volume was analyzed according to metal composition, wire length, number of wires, wire thickness, and imaging sequence as factors.
RESULTS
With SE/GRE, black/white artefacts volumes from all SS wires were significantly larger than those produced by CC and Ti wires (P < 0.01). With the GRE, the black artefacts volume was highest with the SS wires. With the SE, the black artefacts volume was small, whereas white artefacts were noticeable. The cranio-caudal extent of the artefacts was significantly longer with SS wires (P < 0.01). Although a direct relationship of wire length, number of wires and wire thickness with artefact volume was noted, these factors did not influence artefact extension in the cranio-caudal direction.
CONCLUSIONS
Ferromagnetic/paramagnetic orthodontic wires create artefacts due to local alteration of magnetic field homogeneity. The SS-type wires produced the largest artefacts followed by CC and Ti.
Additional Info
MRI susceptibility artefacts caused by orthodontic wire
Dentomaxillofac Radiol 2024 Jun 13;[EPub Ahead of Print], Y Iwamoto, H Shimamoto, D Felemban, T Terai, S Kreiborg, SM Mallya, FP Gloria Yang, C Tanikawa, S MurakamiFrom MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
Dentists are frequently consulted by physicians for the removal of orthodontic appliances for MRI examinations, as the magnetic susceptibility artefacts otherwise produced would render the imaging study nondiagnostic. The findings in this study demonstrate that, sometimes, wire removal is necessary, whereas, in other cases, it is not. The results of this study provide guidance to evaluate the potential for an orthodontic wire to produce artefacts on an MRI image, and the potential of such artefacts to interfere with the diagnostics. General dentists and orthodontists are advised to consult an oral and maxillofacial radiologist for recommendations when an MRI is ordered for a patient undergoing fixed orthodontic therapy.