• Magn Reson Med · Jan 2019

    Changes in the specific absorption rate (SAR) of radiofrequency energy in patients with retained cardiac leads during MRI at 1.5T and 3T.

    • Laleh Golestanirad, Amir Ali Rahsepar, John E Kirsch, Kenichiro Suwa, Jeremy C Collins, Leonardo M Angelone, Boris Keil, Rod S Passman, Giorgio Bonmassar, Peter Serano, Peter Krenz, Jim DeLap, James C Carr... more , and Lawrence L Wald. less
    • Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts.
    • Magn Reson Med. 2019 Jan 1; 81 (1): 653-669.

    PurposeTo evaluate the local specific absorption rate (SAR) and heating around retained cardiac leads during MRI at 64 MHz (1.5T) and 127 MHz (3T) as a function of RF coil type and imaging landmark.MethodsNumerical models of retained cardiac leads were built from CT and X-ray images of 6 patients with retained cardiac leads. Electromagnetic simulations and bio-heat modeling were performed with MRI RF body and head coils tuned to 64 MHz and 127 MHz and positioned at 9 different imaging landmarks covering an area from the head to the lower limbs.ResultsFor all patients and at both 1.5T and 3T, local transmit head coils produced negligible temperature rise ( http://www.w3.org/1998/Math/MathML">Δ T < 0.1 ° C ) for http://www.w3.org/1998/Math/MathML"> B 1 + 3 μ T . For body imaging with quadrature-driven coils at 1.5T, http://www.w3.org/1998/Math/MathML">Δ T during a 10-min scan remained < 3°C at all imaging landmarks for http://www.w3.org/1998/Math/MathML"> B 1 + 3 μ T and <6°C for http://www.w3.org/1998/Math/MathML"> B 1 + 4 μ T . For body imaging at 3T, http://www.w3.org/1998/Math/MathML">Δ T during a 10-min scan remained < 6°C at all imaging landmarks for http://www.w3.org/1998/Math/MathML"> B 1 + 2 μ T . For shorter pulse sequences up to 2 min, http://www.w3.org/1998/Math/MathML">Δ T remained < 6°C for http://www.w3.org/1998/Math/MathML"> B 1 + 3 μ T .ConclusionFor the models based on 6 patients studied, simulations suggest that MRI could be performed safely using a local head coil at both 1.5T and 3T, and with a body coil at 1.5T with pulses that produced http://www.w3.org/1998/Math/MathML"> B 1 + 4 μ T . MRI at 3T could be performed safely in these patients using pulses with http://www.w3.org/1998/Math/MathML"> B 1 + 2 μ T .© 2018 International Society for Magnetic Resonance in Medicine.

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