Matthew R Smith1, Nathan S Artz1, Curtis Wiens1, Diego Hernando1, Scott B Reeder1,2,3,4,5. 1. Department of Radiology, University of Wisconsin, Madison, Wisconsin, USA. 2. Department of Medical Physics, University of Wisconsin, Madison, Wisconsin, USA. 3. Department of Biomedical Engineering, University of Wisconsin, Madison, Wisconsin, USA. 4. Department of Medicine, University of Wisconsin, Madison, Wisconsin, USA. 5. Department of Emergency Medicine, University of Wisconsin, Madison, Wisconsin, USA.
Abstract
PURPOSE: To characterize the fundamental limits of MRI near metallic implants on RF excitation, frequency encoding, and chemical shift-encoding water-fat separation. METHODS: Multicomponent three-dimensional (3D) digital models of a total hip and a total knee replacement were used to construct material-specific susceptibility maps. The fundamental limits and spatial relationship of imaging near metallic prostheses were investigated as a function of distance from the prosthetic surface by calculating 3D field map perturbations using a well-validated k-space based dipole kernel. RESULTS: Regions limited by the bandwidth of RF excitation overlap substantially with those fundamentally limited by frequency encoding. Rapid breakdown of water-fat separation occurs once the intravoxel off-resonance exceeds ∼6 ppm over a full range of fat fractions (0%-100%) and SNR (5-100). CONCLUSION: Current 3D multispectral imaging methods would not benefit greatly from exciting spins beyond ±12 kHz despite the presence of signal that lies outside of this range from tissue directly adjacent to the metallic implants. Methods such as phase encoding in all three spatial dimensions are necessary to spatially resolve spins beyond an excitation bandwidth of ±12 kHz. The approach described in this study provides a benchmark for the capabilities of current imaging techniques to guide development of new MRI methods for imaging near metal.
PURPOSE: To characterize the fundamental limits of MRI near metallic implants on RF excitation, frequency encoding, and chemical shift-encoding water-fat separation. METHODS: Multicomponent three-dimensional (3D) digital models of a total hip and a total knee replacement were used to construct material-specific susceptibility maps. The fundamental limits and spatial relationship of imaging near metallic prostheses were investigated as a function of distance from the prosthetic surface by calculating 3D field map perturbations using a well-validated k-space based dipole kernel. RESULTS: Regions limited by the bandwidth of RF excitation overlap substantially with those fundamentally limited by frequency encoding. Rapid breakdown of water-fat separation occurs once the intravoxel off-resonance exceeds ∼6 ppm over a full range of fat fractions (0%-100%) and SNR (5-100). CONCLUSION: Current 3D multispectral imaging methods would not benefit greatly from exciting spins beyond ±12 kHz despite the presence of signal that lies outside of this range from tissue directly adjacent to the metallic implants. Methods such as phase encoding in all three spatial dimensions are necessary to spatially resolve spins beyond an excitation bandwidth of ±12 kHz. The approach described in this study provides a benchmark for the capabilities of current imaging techniques to guide development of new MRI methods for imaging near metal.
Authors: Mark A Griswold; Peter M Jakob; Robin M Heidemann; Mathias Nittka; Vladimir Jellus; Jianmin Wang; Berthold Kiefer; Axel Haase Journal: Magn Reson Med Date: 2002-06 Impact factor: 4.668
Authors: K M Koch; A C Brau; W Chen; G E Gold; B A Hargreaves; M Koff; G C McKinnon; H G Potter; K F King Journal: Magn Reson Med Date: 2011-01 Impact factor: 4.668
Authors: Gavin Hamilton; Takeshi Yokoo; Mark Bydder; Irene Cruite; Michael E Schroeder; Claude B Sirlin; Michael S Middleton Journal: NMR Biomed Date: 2010-12-12 Impact factor: 4.044
Authors: Thorsten A Bley; Oliver Wieben; Christopher J François; Jean H Brittain; Scott B Reeder Journal: J Magn Reson Imaging Date: 2010-01 Impact factor: 4.813
Authors: Steven Kurtz; Fionna Mowat; Kevin Ong; Nathan Chan; Edmund Lau; Michael Halpern Journal: J Bone Joint Surg Am Date: 2005-07 Impact factor: 5.284
Authors: Christina A Chen; Weitian Chen; Stuart B Goodman; Brian A Hargreaves; Kevin M Koch; Wenmaio Lu; Anja C Brau; Christine E Draper; Scott L Delp; Garry E Gold Journal: J Magn Reson Imaging Date: 2011-05 Impact factor: 4.813
Authors: Nathan S Artz; Curtis N Wiens; Matthew R Smith; Diego Hernando; Alexey Samsonov; Scott B Reeder Journal: Magn Reson Med Date: 2016-03-28 Impact factor: 4.668
Authors: Curtis N Wiens; Nathan S Artz; Hyungseok Jang; Alan B McMillan; Kevin M Koch; Scott B Reeder Journal: Magn Reson Med Date: 2017-08-21 Impact factor: 4.668