1.5 Tおよび3.0 T-MRI検査における歯科用チタン(Ti)製インプラントのRF発熱に関する検討: 人体等価ファントムを用いた温度測定

摘要

Titanium (Ti) implants are increasingly being used for dental parts. There is no problem with the attraction of a static magnetic field for Ti in magnetic resonance imaging (MRI), since Ti is paramagnetic. However, there is a risk of radio frequency (RF) heat generation within Ti. 3.0 T-MRI scanners are becoming increasingly common. The specific absorption rate (SAR) of 3.0 T-MRI is quadruple that of SAR compared with 1.5 T-MRI due to its being proportional to the square of the strength of a static magnetic field. The effect of heat generation in 3.0 T-MRI can thus be greater than in 1.5 T-MRI. So, using 1.5 T and 3.0 T-MRI scanners, we measured the temperature of several Ti implants using the same scanning parameters during MRI scanning. Our measurements showed the rise in temperature of the Ti implants to be a maximum of 0.4°C. In this study, however, Ti in a human mouth was not directly measured, so we need to attempt to perform MRI carefully on patients with Ti implants.%近年，歯科治療においてチタン（titanium: Ti)製インプラントが多く用いられている.Tiは常磁性体であるため，magnetic resonance imaging(MRI)検査にぉぃて静磁場の吸引力に関して問題はない.しかし，radio frequency (RF)による発熱の可能性があるため，安全であるとは断言できない.村中らの報告によれば specific absorption rate(SAR)の増加は金属インプラントのRF発熱に影響を与えると述べている.