Laleh Golestanirad1,2, Amir Ali Rahsepar2, John E Kirsch1, Kenichiro Suwa2, Jeremy C Collins2, Leonardo M Angelone3, Boris Keil4, Rod S Passman5, Giorgio Bonmassar1, Peter Serano3, Peter Krenz6, Jim DeLap6, James C Carr2, Lawrence L Wald1. 1. Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts. 2. Department of Radiology, Northwestern University, Feinberg School of Medicine, Chicago, Illinois. 3. Division of Biomedical Physics, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, Maryland. 4. Department of Life Science Engineering, Institute of Medical Physics and Radiation Protection, Giessen, Germany. 5. Division of Cardiology, Department of Medicine, Northwestern University, Feinberg School of Medicine, Chicago, Illinois. 6. ANSYS Inc., Canonsburg, Pennsylvania.
Abstract
PURPOSE: To 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. METHODS: Numerical 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. RESULTS: For all patients and at both 1.5T and 3T, local transmit head coils produced negligible temperature rise ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mo>Δ</mml:mo> <mml:mi>T</mml:mi> <mml:mo><</mml:mo> <mml:mn>0.1</mml:mn> <mml:mo>°</mml:mo> <mml:mi>C</mml:mi></mml:mrow> </mml:math> ) for <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow><mml:mrow><mml:mo>‖</mml:mo> <mml:mo>‖</mml:mo> <mml:mrow><mml:msubsup><mml:mi>B</mml:mi> <mml:mn>1</mml:mn> <mml:mo>+</mml:mo></mml:msubsup> </mml:mrow> <mml:mo>‖</mml:mo> <mml:mo>‖</mml:mo></mml:mrow> <mml:mo>≤</mml:mo> <mml:mn>3</mml:mn> <mml:mo> </mml:mo> <mml:mo>μ</mml:mo> <mml:mi>T</mml:mi></mml:mrow> </mml:math> . For body imaging with quadrature-driven coils at 1.5T, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mo>Δ</mml:mo> <mml:mi>T</mml:mi></mml:mrow> </mml:math> during a 10-min scan remained < 3°C at all imaging landmarks for <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow><mml:mrow><mml:mo>‖</mml:mo> <mml:mo>‖</mml:mo> <mml:mrow><mml:msubsup><mml:mi>B</mml:mi> <mml:mn>1</mml:mn> <mml:mo>+</mml:mo></mml:msubsup> </mml:mrow> <mml:mo>‖</mml:mo> <mml:mo>‖</mml:mo></mml:mrow> <mml:mo>≤</mml:mo> <mml:mn>3</mml:mn> <mml:mo> </mml:mo> <mml:mo>μ</mml:mo> <mml:mi>T</mml:mi></mml:mrow> </mml:math> and <6°C for <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow><mml:mrow><mml:mo>‖</mml:mo> <mml:mo>‖</mml:mo> <mml:mrow><mml:msubsup><mml:mi>B</mml:mi> <mml:mn>1</mml:mn> <mml:mo>+</mml:mo></mml:msubsup> </mml:mrow> <mml:mo>‖</mml:mo> <mml:mo>‖</mml:mo></mml:mrow> <mml:mo>≤</mml:mo> <mml:mn>4</mml:mn> <mml:mo> </mml:mo> <mml:mo>μ</mml:mo> <mml:mi>T</mml:mi></mml:mrow> </mml:math> . For body imaging at 3T, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mo>Δ</mml:mo> <mml:mi>T</mml:mi></mml:mrow> </mml:math> during a 10-min scan remained < 6°C at all imaging landmarks for <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow><mml:mrow><mml:mo>‖</mml:mo> <mml:mo>‖</mml:mo> <mml:mrow><mml:msubsup><mml:mi>B</mml:mi> <mml:mn>1</mml:mn> <mml:mo>+</mml:mo></mml:msubsup> </mml:mrow> <mml:mo>‖</mml:mo> <mml:mo>‖</mml:mo></mml:mrow> <mml:mo>≤</mml:mo> <mml:mn>2</mml:mn> <mml:mo> </mml:mo> <mml:mo>μ</mml:mo> <mml:mi>T</mml:mi></mml:mrow> </mml:math> . For shorter pulse sequences up to 2 min, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mo>Δ</mml:mo> <mml:mi>T</mml:mi></mml:mrow> </mml:math> remained < 6°C for <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow><mml:mrow><mml:mo>‖</mml:mo> <mml:mo>‖</mml:mo> <mml:mrow><mml:msubsup><mml:mi>B</mml:mi> <mml:mn>1</mml:mn> <mml:mo>+</mml:mo></mml:msubsup> </mml:mrow> <mml:mo>‖</mml:mo> <mml:mo>‖</mml:mo></mml:mrow> <mml:mo>≤</mml:mo> <mml:mn>3</mml:mn> <mml:mo> </mml:mo> <mml:mo>μ</mml:mo> <mml:mi>T</mml:mi></mml:mrow> </mml:math> . CONCLUSION: For 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 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow><mml:mrow><mml:mo>‖</mml:mo> <mml:mo>‖</mml:mo> <mml:mrow><mml:msubsup><mml:mi>B</mml:mi> <mml:mn>1</mml:mn> <mml:mo>+</mml:mo></mml:msubsup> </mml:mrow> <mml:mo>‖</mml:mo> <mml:mo>‖</mml:mo></mml:mrow> <mml:mo>≤</mml:mo> <mml:mn>4</mml:mn> <mml:mo> </mml:mo> <mml:mo>μ</mml:mo> <mml:mi>T</mml:mi></mml:mrow> </mml:math> . MRI at 3T could be performed safely in these patients using pulses with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow><mml:mrow><mml:mo>‖</mml:mo> <mml:mo>‖</mml:mo> <mml:mrow><mml:msubsup><mml:mi>B</mml:mi> <mml:mn>1</mml:mn> <mml:mo>+</mml:mo></mml:msubsup> </mml:mrow> <mml:mo>‖</mml:mo> <mml:mo>‖</mml:mo></mml:mrow> <mml:mo>≤</mml:mo> <mml:mn>2</mml:mn> <mml:mo> </mml:mo> <mml:mo>μ</mml:mo> <mml:mi>T</mml:mi></mml:mrow> </mml:math> .
PURPOSE: To 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. METHODS: Numerical 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. RESULTS: For all patients and at both 1.5T and 3T, local transmit head coils produced negligible temperature rise ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mo>Δ</mml:mo> <mml:mi>T</mml:mi> <mml:mo><</mml:mo> <mml:mn>0.1</mml:mn> <mml:mo>°</mml:mo> <mml:mi>C</mml:mi></mml:mrow> </mml:math> ) for <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow><mml:mrow><mml:mo>‖</mml:mo> <mml:mo>‖</mml:mo> <mml:mrow><mml:msubsup><mml:mi>B</mml:mi> <mml:mn>1</mml:mn> <mml:mo>+</mml:mo></mml:msubsup> </mml:mrow> <mml:mo>‖</mml:mo> <mml:mo>‖</mml:mo></mml:mrow> <mml:mo>≤</mml:mo> <mml:mn>3</mml:mn> <mml:mo> </mml:mo> <mml:mo>μ</mml:mo> <mml:mi>T</mml:mi></mml:mrow> </mml:math> . For body imaging with quadrature-driven coils at 1.5T, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mo>Δ</mml:mo> <mml:mi>T</mml:mi></mml:mrow> </mml:math> during a 10-min scan remained < 3°C at all imaging landmarks for <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow><mml:mrow><mml:mo>‖</mml:mo> <mml:mo>‖</mml:mo> <mml:mrow><mml:msubsup><mml:mi>B</mml:mi> <mml:mn>1</mml:mn> <mml:mo>+</mml:mo></mml:msubsup> </mml:mrow> <mml:mo>‖</mml:mo> <mml:mo>‖</mml:mo></mml:mrow> <mml:mo>≤</mml:mo> <mml:mn>3</mml:mn> <mml:mo> </mml:mo> <mml:mo>μ</mml:mo> <mml:mi>T</mml:mi></mml:mrow> </mml:math> and <6°C for <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow><mml:mrow><mml:mo>‖</mml:mo> <mml:mo>‖</mml:mo> <mml:mrow><mml:msubsup><mml:mi>B</mml:mi> <mml:mn>1</mml:mn> <mml:mo>+</mml:mo></mml:msubsup> </mml:mrow> <mml:mo>‖</mml:mo> <mml:mo>‖</mml:mo></mml:mrow> <mml:mo>≤</mml:mo> <mml:mn>4</mml:mn> <mml:mo> </mml:mo> <mml:mo>μ</mml:mo> <mml:mi>T</mml:mi></mml:mrow> </mml:math> . For body imaging at 3T, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mo>Δ</mml:mo> <mml:mi>T</mml:mi></mml:mrow> </mml:math> during a 10-min scan remained < 6°C at all imaging landmarks for <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow><mml:mrow><mml:mo>‖</mml:mo> <mml:mo>‖</mml:mo> <mml:mrow><mml:msubsup><mml:mi>B</mml:mi> <mml:mn>1</mml:mn> <mml:mo>+</mml:mo></mml:msubsup> </mml:mrow> <mml:mo>‖</mml:mo> <mml:mo>‖</mml:mo></mml:mrow> <mml:mo>≤</mml:mo> <mml:mn>2</mml:mn> <mml:mo> </mml:mo> <mml:mo>μ</mml:mo> <mml:mi>T</mml:mi></mml:mrow> </mml:math> . For shorter pulse sequences up to 2 min, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mo>Δ</mml:mo> <mml:mi>T</mml:mi></mml:mrow> </mml:math> remained < 6°C for <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow><mml:mrow><mml:mo>‖</mml:mo> <mml:mo>‖</mml:mo> <mml:mrow><mml:msubsup><mml:mi>B</mml:mi> <mml:mn>1</mml:mn> <mml:mo>+</mml:mo></mml:msubsup> </mml:mrow> <mml:mo>‖</mml:mo> <mml:mo>‖</mml:mo></mml:mrow> <mml:mo>≤</mml:mo> <mml:mn>3</mml:mn> <mml:mo> </mml:mo> <mml:mo>μ</mml:mo> <mml:mi>T</mml:mi></mml:mrow> </mml:math> . CONCLUSION: For 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 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow><mml:mrow><mml:mo>‖</mml:mo> <mml:mo>‖</mml:mo> <mml:mrow><mml:msubsup><mml:mi>B</mml:mi> <mml:mn>1</mml:mn> <mml:mo>+</mml:mo></mml:msubsup> </mml:mrow> <mml:mo>‖</mml:mo> <mml:mo>‖</mml:mo></mml:mrow> <mml:mo>≤</mml:mo> <mml:mn>4</mml:mn> <mml:mo> </mml:mo> <mml:mo>μ</mml:mo> <mml:mi>T</mml:mi></mml:mrow> </mml:math> . MRI at 3T could be performed safely in these patients using pulses with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow><mml:mrow><mml:mo>‖</mml:mo> <mml:mo>‖</mml:mo> <mml:mrow><mml:msubsup><mml:mi>B</mml:mi> <mml:mn>1</mml:mn> <mml:mo>+</mml:mo></mml:msubsup> </mml:mrow> <mml:mo>‖</mml:mo> <mml:mo>‖</mml:mo></mml:mrow> <mml:mo>≤</mml:mo> <mml:mn>2</mml:mn> <mml:mo> </mml:mo> <mml:mo>μ</mml:mo> <mml:mi>T</mml:mi></mml:mrow> </mml:math> .
Authors: Peter Nordbeck; Florian Fidler; Ingo Weiss; Marcus Warmuth; Michael T Friedrich; Philipp Ehses; Wolfgang Geistert; Oliver Ritter; Peter M Jakob; Mark E Ladd; Harald H Quick; Wolfgang R Bauer Journal: Magn Reson Med Date: 2008-08 Impact factor: 4.668
Authors: Arnold J Greenspon; Jasmine D Patel; Edmund Lau; Jorge A Ochoa; Daniel R Frisch; Reginald T Ho; Behzad B Pavri; Steven M Kurtz Journal: J Am Coll Cardiol Date: 2012-09-19 Impact factor: 24.094
Authors: Eugenio Mattei; Michele Triventi; Giovanni Calcagnini; Federica Censi; Wolfgang Kainz; Gonzalo Mendoza; Howard I Bassen; Pietro Bartolini Journal: Biomed Eng Online Date: 2008-03-03 Impact factor: 2.819
Authors: Laleh Golestanirad; Ehsan Kazemivalipour; Boris Keil; Sean Downs; John Kirsch; Behzad Elahi; Julie Pilitsis; Lawrence L Wald Journal: PLoS One Date: 2019-08-07 Impact factor: 3.240
Authors: Bach T Nguyen; Bhumi Bhusal; Amir Ali Rahsepar; Kate Fawcett; Stella Lin; Daniel S Marks; Rod Passman; Donny Nieto; Richard Niemzcura; Laleh Golestanirad Journal: Magn Reson Med Date: 2021-12-27 Impact factor: 3.737