SAR Computation inside Fetus by RF Coil during MR Imaging Employing Realistic Numerical Pregnant Woman Model

Satoru KIKUCHI  Kazuyuki SAITO  Masaharu TAKAHASHI  Koichi ITO  Hiroo IKEHIRA  

IEICE TRANSACTIONS on Communications   Vol.E92-B   No.2   pp.431-439
Publication Date: 2009/02/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.E92.B.431
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Medical Information and Communications Technologies)
magnetic resonance imaging (MRI),  birdcage coil,  pregnant woman,  fetus,  specific absorption rate (SAR),  

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This paper presents the computational electromagnetic dosimetry inside an anatomically based pregnant woman models exposed to electromagnetic wave during magnetic resonance imaging. The two types of pregnant woman models corresponding to early gestation and 26 weeks gestation were used for this study. The specific absorption rate (SAR) in and around a fetus were calculated by radiated electromagnetic wave from highpass and lowpass birdcage coil. Numerical calculation results showed that high SAR region is observed at the body in the vicinity of gaps of the coil, and is related to concentrated electric field in the gaps of human body such as armpit and thigh. Moreover, it has confirmed that the SAR in the fetus is less than International Electrotechnical Commission limit of 10 W/kg, when whole-body average SARs are 2 W/kg and 4 W/kg, which are the normal operating mode and first level controlled operating mode, respectively.