• 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, and Lawrence L Wald.
    • 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.

      Pubmed     Full text   Copy Citation     Plaintext  

      Add institutional full text...

    Notes

     
    Knowledge, pearl, summary or comment to share?
    300 characters remaining
    help        
    You can also include formatting, links, images and footnotes in your notes
    • Simple formatting can be added to notes, such as *italics*, _underline_ or **bold**.
    • Superscript can be denoted by <sup>text</sup> and subscript <sub>text</sub>.
    • Numbered or bulleted lists can be created using either numbered lines 1. 2. 3., hyphens - or asterisks *.
    • Links can be included with: [my link to pubmed](http://pubmed.com)
    • Images can be included with: ![alt text](https://bestmedicaljournal.com/study_graph.jpg "Image Title Text")
    • For footnotes use [^1](This is a footnote.) inline.
    • Or use an inline reference [^1] to refer to a longer footnote elseweher in the document [^1]: This is a long footnote..

    hide…