[Impact of magnetic attachment keepers on magnetic resonance imaging examination].
OBJECTIVE
To evaluate the effects of magnetic attachment keepers on MRI images.


METHODS
In in vitro part, keepers of MAGFIT EX 400, MAGFIT EX 600 and MAGNEDISC 800 magnetic attachment systems were cast into standard root-caps with different alloy respectively, including nickel-chromium alloy and gold-palladium alloy, or not be cast for contrast. In in vivo part, volunteers with keepers in different position and amount were included. All the specimens and volunteers were imaged by a Siemens SONATA 1.5-T MRI scanner. Extent of the artifacts in every slice was measured. The magnitude of the artifacts and the distortion of the anatomic structures were compared.


RESULTS
All kinds of keepers being studied produced obvious MRI artifacts. The extent of MRI artifacts induced by MAGFIT EX 400 keepers, MAGFIT EX 600 keepers and MAGNEDISC 800 keepers are 158.94 mm, 168.52 mm and 173.00 mm, respectively. The images of mental region, tongue, palate, jawbone and sinus were evidently obscured by artifacts in all cases. When keeper was put in the molar region, the keeper-related MRI artifact may obscure the imaging of brain, spinal cord. SE sequence with right-left frequency-encoding direction was more desirable in MRI for the patients with magnetic attachment keepers.


CONCLUSIONS
Keepers of magnetic attachment system did induce obvious artifacts in MRI examination.
Zhao
Xue-zhu
XZ
Departmont of Prosthodontics, Peking University School of Stomatology, Beijing 100081, China.
Liu
Yu-hua
YH
Xu
Jun
J
Han
Hong-bin
HB
Xu
Xiao-juan
XJ
D016477:Artifacts; D001921:Brain / Q000033:anatomy & histology; D003832:Denture, Partial, Removable; D006801:Humans; D008279:Magnetic Resonance Imaging; D008280:Magnetics; D008670:Metals; D019047:Phantoms, Imaging
D008670:Metals