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Prediction of specific absorption rate in mother and fetus associated with MRI examinations during pregnancy
Author(s) -
Hand J.W.,
Li Y.,
Thomas E.L.,
Rutherford M.A.,
Hajnal J.V.
Publication year - 2006
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.20824
Subject(s) - specific absorption rate , magnetic resonance imaging , medicine , pregnancy , nuclear medicine , fetus , radiology , physics , computer science , telecommunications , genetics , biology , antenna (radio)
There is uncertainty regarding the risk posed by magnetic resonance imaging (MRI) examinations to pregnant patients. The most frequently used methods, such as single‐shot fast spin echo (ssFSE), often require operation at the specific absorption rate (SAR) limits imposed by safety guidelines. With the introduction of higher‐field systems, such limits will be even more significant for fetal imaging. An electromagnetic solver based on the time domain finite integration technique (FIT) was used to predict SAR in an anatomically realistic model of a pregnant patient (28 weeks' gestation) associated with the radiofrequency (RF) fields from birdcage body coils typical of 1.5 T and 3 T MRI systems (i.e., operating at approximately 64 and 127 MHz, respectively). The results suggest that 1) the highest local SAR is in the mother, with the fetus being exposed to a peak of approximately 40–60% of that value at 64 MHz, increasing to approximately 50–70% at 127 MHz; 2) compliance with U.S. Food and Drug Administration (FDA) and International Commission on Non‐Ionizing Radiation Protection (ICNIRP) guidelines requires control of SAR values averaged over 1 g or 10 g of tissue, respectively; and 3) compliance with Medical Device Agency (MDA) guidelines requires control of the maximum SAR 10g within the fetus. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.