Performance evaluation of matrix gradient coils

Feng Jia1, Gerrit Schultz1, Frederik Testud1, Anna Masako Welz1, Hans Weber1, Sebastian Littin1, Huijun Yu1, Jürgen Hennig1, Maxim Zaitsev1
1Medical Physics, Department of Radiology, University Medical Center Freiburg, Freiburg, Germany

Tóm tắt

In this paper, we present a new performance measure of a matrix coil (also known as multi-coil) from the perspective of efficient, local, non-linear encoding without explicitly considering target encoding fields. An optimization problem based on a joint optimization for the non-linear encoding fields is formulated. Based on the derived objective function, a figure of merit of a matrix coil is defined, which is a generalization of a previously known resistive figure of merit for traditional gradient coils. A cylindrical matrix coil design with a high number of elements is used to illustrate the proposed performance measure. The results are analyzed to reveal novel features of matrix coil designs, which allowed us to optimize coil parameters, such as number of coil elements. A comparison to a scaled, existing multi-coil is also provided to demonstrate the use of the proposed performance parameter. The assessment of a matrix gradient coil profits from using a single performance parameter that takes the local encoding performance of the coil into account in relation to the dissipated power.

Tài liệu tham khảo

Hennig J, Welz AM, Schultz G, Korvink J, Liu Z, Speck O, Zaitsev M (2008) Parallel imaging in non-bijective, curvilinear magnetic field gradients: a concept study. Magn Reson Mater Phy 21:5–14 Schultz G, Ullmann P, Lehr H, Welz AM, Hennig J, Zaitsev M (2010) Reconstruction of MRI data encoded with arbitrarily shaped, curvilinear, non-bijective magnetic fields. Magn Reson Med 64:1390–1404 Gallichan D, Cocosco CA, Dewdney A, Schultz G, Welz AM, Hennig J, Zaitsev M (2011) Designing k-space trajectories for simultaneous encoding with linear and PatLoc gradients. Magn Reson Med 65:702–714 Layton KJ, Gallichan D, Testud F, Cocosco CA, Welz AM, Barmet C, Pruessmann KP, Hennig J, Zaitsev M (2013) Single shot trajectory design for region-specific imaging using linear and nonlinear magnetic encoding fields. Magn Reson Med 70:684–696 Stockmann JP, Ciris PA, Galiana G, Tam LK, Constable RT (2010) O-space imaging: highly efficient parallel imaging using second-order nonlinear fields as encoding gradients with no phase encoding. Magn Reson Med 64:447–456 Weber H, Schultz G, Gallichan D, Hennig J, Zaitsev M (2014) Local field of view imaging for alias-free undersampling with nonlinear spatial encoding magnetic fields. Magn Reson Med 71:1002–1014 Tam LK, Stockmann JP, Galiana G, Constable RT (2012) Null space imaging: nonlinear magnetic encoding fields designed complementary to receiver coil sensitivities for improved acceleration in parallel imaging. Magn Reson Med 68:447–456 Lin FH, Witzel T, Schultz G, Gallichan D, Kuo WJ, Wang FN, Hennig J, Zaitsev M, Belliveau JW (2012) Reconstruction of MRI data encoded by multiple non-bijective curvilinear magnetic fields. Magn Reson Med 68:1145–1156 Lin FH (2013) Multidimensionally encoded magnetic resonance imaging. Magn Reson Med 70:86–96 Weber H, Galiana G, Schultz G, Cocosco CA, Littin S, Reichardt W, Welz AM, Witschey W, Hennig J, Zaitsev M (2013) Excitation and geometrically matched local encoding of curved slices. Magn Reson Med 69:1317–1325 Weber H, Littin S, Galiana G, Jia F, Welz AM, Constable RT, Hennig J, Zaitsev M (2013) 3d curved slice imaging. In: Proceedings of the 21st annual meeting, international society for magnetic resonance, Salt Lake City, Utah, USA, p 2384 Witschey W, Cocosco CA, Gallichan D, Schultz G, Weber H, Welz A, Hennig J, Zaitsev M (2012) Localization by nonlinear phase preparation and k-space trajectory design. Magn Reson Med 67:1620–1632 Wiesler DG, Wen H, Wolff SD, Balaban RS (1998) Reduction of field of view in MRI using a surface-spoiling local gradient insert. J Magn Reson Imaging 8:981–988 Littin S, Zaitsev M, Buchenberg WB, Welz AM, Weber H, Jia F, Testud F, Gallichan D, Hennig J, Witschey WRT (2014) Zoomed cardiac CINE-MRI using nonlinear phase preparation. In: Proceedings of the 22nd annual meeting, international society for magnetic resonance in medicine, Milan, p 0428 Zaitsev M, Punchard W, Dewdney A, Galiana G, Stockmann JP, Cocosco CA, Littin S, Welz AM, Weber H, Starewicz P, Hennig J (2012) Design and implementation of high-performance non-linear patloc gradient coil. In: Proceedings of the 20th annual meeting, international society for magnetic resonance, Melbourne, Australia, p 2591 Welz AM, Cocosco CA, Dewdney A, Gallichan D, Jia F, Lehr H, Liu Z, Post H, Schmidt H, Schultz G, Testud F, Weber H, Witschey W, Krovink J, Hennig J, Zaitsev M (2013) Development and characterisation of an unshielded patloc gradient coil for human head imaging. Concepts Magn Reson Part B Magn Reson Eng 43B:111–125 Littin S, Gallichan D, Welz AM, Jia F, Dewdney A, Weber H, Schultz G, Hennig J, Zaitse M (2015) Monoplanar gradient system for imaging with nonlinear gradients. Magn Reson Mater Phy. doi:10.1007/s10334-015-0481-8 Juchem C, Nixon TW, McIntyre S, Rothman DL, de Graaf RA (2010) Magnetic field modeling with a set of individual localized coils. J Magn Reson 204:281–289 Wintzheimer S, Driessle T, Ledwig M, Jakob PM, Fidler F (2010) A 50-channel matrix gradient system: a feasibility study. In: Proceedings of the joint annual meeting ISMRM-ESMRMB, Stockholm, Sweden, p 3937 Juchem C, Brown PB, Nixon TW, McIntyre S, Rothman DL, de Graaf RA (2011) Multicoil shimming of the mouse brain. Magn Reson Med 66:893–900 Juchem C, Nixon TW, de Graaf RA (2012) Multi-coil imaging with algebraic reconstruction. In: Proceedings of the 20th annual meeting, international society for magnetic resonance, Melbourne, Australia, p 2545 Juchem C, Green D, de Graaf RA (2013) Multi-coil magnetic field modelling. J Magn Reson 236:95–104 While PT, Korvink JG (2014) Designing MR shim arrays with irregular coil geometry: theoretical considerations. IEEE Trans Biomed Eng 61:1614–1620 Poole MS, While PT, Lopez HS, Crozier S (2012) Minimax current density gradient coils: analysis of coil performance and heating. Magn Reson Med 68:639–648 Golay MJE (1958) Field homogenizing coils for nuclear spin resonance instrumentation. Rev Sci Instrum 29:313–315 Roméo F, Hoult DI (1984) Magnet field profiling: analysis and correcting coil design. Magn Reson Med 1:44–65 Layton KJ, Jia F, Zaitsev M (2014) Optimal trajectory design for higher-dimensional encoding. In: Proceedings of the joint annual meeting ISMRM-ESMRMB 2014, Milan, Italy, p 32 Layton KJ, Kroboth S, Jia F, Littin S, Yu H, Zaitsev M (2015) Trajectory optimization based on the signal-to-noise ratio for spatial encoding with nonlinear encoding fields. Magn Reson Med. doi:10.1002/mrm.25859 Jia F, Littin S, Layton KJ, Kroboth S, Yu H, Hennig J, Zaitsev M (2015) Design of a shielded coil element of a matrix gradient coil. In: Proceedings of the 23rd annual meeting, international society for magnetic resonance, Toronto, Canada, p 3091 Littin S, Jia F, Kroboth S, Layton KJ, Yu H, Zaitsev M (2015) Shielded matrix gradient coil. In: Proceedings of the 23rd annual meeting, international society for magnetic resonance, Toronto, Canada, p 1022