TITLE:
MRI-Induced Tissue Heating at Metallic Sutures (Cerclages)
AUTHORS:
Norbert Leitgeb, Gerhard Loos, Franz Ebner
KEYWORDS:
Metallic Implants; Health Risk; Tissue Damage; Safety; Radio Frequency Electromagnetic Fields
JOURNAL NAME:
Journal of Electromagnetic Analysis and Applications,
Vol.5 No.9,
September
27,
2013
ABSTRACT:
Magnetic
resonance imaging (MRI) has become an important diagnostic tool with an ongoing dynamic development towards application of increasing
static magnetic flux densities and consequently, exposures to electromagnetic
fields (EMF) of increasing radio frequencies (RF). This raises particular concern
metallic implants could lead to excess
tissue heating and consequently, to thermal tissue damage. In thorax surgery
the intersected sternum is reconnected by metallic sutures (cerclages). To
investigate whether patients with such implants can be accepted for MRI and
whether there may be limitations with regard to static magnetic fields, by
numerical anatomical and thermal modelling MRI induced tissue heating was assessed for magnetic flux densities 1.5 T, 3 T, 4 T and 7 T. Results show that
overall tissue temperature increased with increasing RF EMF frequency. However,
even for setting MRI exposure parameters at maximum permissible level partial
body heating remained marginally affected and even at local level the
additional contribution of the presence of the metallic cerclage remained below 1°C. This allows concluding that from a heating point of view metallic
sutures as used to fix the sternum after thorax surgery are no contraindication
for MRI with static magnetic flux densities up to 7 T.