Full Paper
B1 and B0 inhomogeneity mitigation in the human brain at 7 T with selective pulses by using average Hamiltonian theory
N. Boulant,
M. A. Cloos,
A. Amadon,
Corresponding Author
N. Boulant
CEA, DSV, I2BM, NeuroSpin, LRMN, Gif sur Yvette Cedex, 91191, France
Bât 145, NeuroSpin, CEA Saclay, 91191, Gif sur Yvette Cedex, France===Search for more papers by this authorM. A. Cloos
CEA, DSV, I2BM, NeuroSpin, LRMN, Gif sur Yvette Cedex, 91191, France
Search for more papers by this authorA. Amadon
CEA, DSV, I2BM, NeuroSpin, LRMN, Gif sur Yvette Cedex, 91191, France
Search for more papers by this authorN. Boulant,
M. A. Cloos,
A. Amadon,
Corresponding Author
N. Boulant
CEA, DSV, I2BM, NeuroSpin, LRMN, Gif sur Yvette Cedex, 91191, France
Bât 145, NeuroSpin, CEA Saclay, 91191, Gif sur Yvette Cedex, France===Search for more papers by this authorM. A. Cloos
CEA, DSV, I2BM, NeuroSpin, LRMN, Gif sur Yvette Cedex, 91191, France
Search for more papers by this authorA. Amadon
CEA, DSV, I2BM, NeuroSpin, LRMN, Gif sur Yvette Cedex, 91191, France
Search for more papers by this authorAbstract
A novel method based on average Hamiltonian theory to design selective pulses is reported. With this tool, it is first shown how to shape the radiofrequency and gradient pulses to generate a desired rotation matrix, which is independent of the position through the slice of interest. After theoretical examination of the concept, it is applied to the strongly modulating pulses' recipe developed by the same authors and initially designed to be nonselective, to mitigate the amplitude of (excitation) radiofrequency field and amplitude of static (polarizing) field inhomogeneity problems at high field. Two in vivo human brain imaging experiments at 7 T are reported to prove the validity of the technique. Magn Reson Med, 2011. © 2010 Wiley-Liss, Inc.
REFERENCES
- 1 Van de Moortele PF, Akgun C, Adriany G, Moeller S, Ritter J, Collins CM, Smith MB, Vaughan JT, Ugurbil K. B1 Destructive interferences and spatial phase patterns at 7 T with a head transceiver array coil. Magn Reson Med 2005; 54: 1503–1518.
- 2 Yang QX, Wang J, Zhang X, Collins CM, Smith MB, Liu H, Zhu XH, Vaughan JT, Ugurbil K, Chen W. Analysis of wave behaviour in lossy dielectric samples at high field. Magn Reson Med 2002; 47: 982–989.
- 3 Mao W, Smith MB, Collins CM. Exploring the limits of RF-shimming for high-field MRI of the human head. Magn Res Med 2006; 56: 918–922.
- 4 Saekho S, Yip CY, Noll DC, Boada FE, Stenger VA. Fast-kz three-dimensional tailored radiofrequency pulse for reduced B1 inhomogeneity. Magn Reson Med 2006; 55: 719–724.
- 5 Zelinski AC, Wald LL, Setsompop K, Alagappan V, Gagoski BA, Goyal VK, Adalsteinsson E. Fast Slice-Selective Radio-Frequency Excitation Pulses for Mitigating B1 Inhomogeneity in the Human Brain at 7 Tesla. Magn Reson Med 2008; 59: 1355–1364.
- 6 Vaughan JT, DelaBarre L, Snyder C, Tian J, Akgun C, Shrivastava D, Liu W, Olson C, Adriany G, Strupp J, Andersen P, Gopinath A, Van de Moortele PF, Garwood M, Ugurbil K. 9.4 T human MRI: Preliminary results. Magn Reson Med 2006; 56: 1274–1282.
- 7 Katscher U, Bornert P, Leussler C, van den Brink JS. Transmit SENSE. Magn Reson Med 2003; 49: 144–150.
- 8 Zhu Y. Parallel excitation with an array of transmit coils. Magn Reson Med 2004; 51: 775–784.
- 9 Grissom W, Yip C-Y, Zhang Z, Stenger A, Fessler JA, Noll DC. Spatial domain method for the design of RF pulses in multicoil parallel excitation. Magn Reson Med 2006; 56: 620–629.
- 10 Ullmann P, Junge S, Wick M, Ruhm W, Hennig J. Experimental analysis of parallel excitation using dedicated coil setups and simultaneous RF transmission on multiple channels. Magn Reson Med ( 2005); 54: 994–1001.
- 11 Collins CM, Smith MB, Wang Z, Mao W. Calculation of SAR for transmit coil arrays. Concepts Magn Reson Part B 2007; 34B: 127–131.
- 12 Boulant N, Mangin J-F, Amadon A. Counteracting RF inhomogeneity in the human brain at 7 T using strongly modulating pulses. Magn Reson Med 2009; 61: 1165–1172.
- 13 Boulant N, Le Bihan D, Amadon A. Strongly modulating pulses: a new method for tackling RF inhomogeneity problems at high fields. Magn Reson Med 2008; 60: 701–708.
- 14 Fortunato EM, Pravia MA, Boulant N, Teklemariam G, Havel TF, Cory DG. Design of strongly modulating pulses to implement precise effective Hamiltonians for quantum information processing. J Chem Phys 2002; 116: 7599–7606.
- 15 Pauly J, Nishimura D, Macovski A. A k-space analysis of small tip angle excitation. J Magn Reson 1989; 81: 43–56.
- 16 Pauly J, Nishimura D, Macovski A. A linear class of large-tip-angle selective excitation pulses. J Magn Reson 1989; 82: 571–587.
- 17 Haerberlen U, Waugh JS. Coherent averaging effects in magnetic resonance. Phys Rev 1968; 175: 453–467.
- 18 Cory DG, Miller JB, Turner R, Garroway AN. Multiple pulse methods of 1H NMR imaging of solids: second averaging. Mol Phys 1990; 70: 331–345.
- 19 Silver MS, Joseph RI, Hoult DI. Selective spin inversion in nuclear magnetic resonance and coherent optics through an exact solution of the Bloch-Riccati equation. Phys Rev A 1985; 31: 2753–2755.
- 20 Pechukas P, Light JC. On the exponential form of the time-displacement operator in quantum mechanics. J Chem Phys 1966; 44: 3897.
- 21 Haeberlen U. High resolution NMR in solids: selective averaging. New York: Academic Press; 1976.
- 22 Thesen S, Krueger G, Mueller E. Compensation of dielectric resonance effects by means of composite excitation pulses. Proceedings of the 11th Annual Meeting of the ISMRM, Toronto, Canada, 2003 (abstract 715).
- 23 Matson GB, Kaiser LG, Young K. Proceedings of the 15th Annual Meeting of the ISMRM, Berlin, Germany, 2007 (abstract 1682).
- 24 Chen Y, Young K, Schleich T, Matson GB. Proceedings of the 11th Annual Meeting of the ISMRM, Kyoto, Japan, 2004 (abstract 2652).
- 25 Ernst RR, Bodenhausen G, Wokaun A. Principles of magnetic resonance in one and two dimensions. Oxford: Oxford university Press; 2004.
- 26 Yarnykh VL. Actual flip-angle imaging in the pulsed steady state: a method for rapid three dimensional mapping of the transmitted radiofrequency field. Magn Reson Med 2007; 57: 192–200.
- 27 Amadon A, Boulant N. MAFI sequence: simultaneous cartography of B0 and B1. Proceedings of the 16th Annual Meeting of ISMRM, Toronto, Canada, 2008 (abstract 1248).
- 28 Powell MJD. An efficient method for finding the minimum of a function of several variables without calculating derivatives. Comput J 1964; 7: 152–162.
- 29 Pfeuffer J, Merkle H, Beyerlein M, Steudel T, Logothetis NK. Anatomical and functional MR imaging in the macaque monkey using a vertical large-bore 7 Tesla setup. Magn Reson Imag 2004; 10: 1343–1359.
- 30 Wu X, Deelchand DK, Yarnykh VL, Ugurbil K, Van de Moortele P-F. Actual Flip Angle Imaging: from 3D to 2D. Proceedings of the 17th Annual meeting of ISMRM, Honolulu, Hawaii, USA, 2009 (abstract 372).
- 31 Grissom WA, Yip C-Y, Wright SM, Fessler JA, Noll DC. Additive angle method for fast large-tip-angle RF pulse design in parallel excitation. Magn Reson Med 2008; 59: 779–787.
- 32 Setsompop K, Wald LL, Alagappan V, Gagoski BA, Adalsteinsson E. Magnitude least squares optimization for parallel radio frequency excitation design demonstrated at 7 Tesla with eight channels. Magn Reson Med 2008; 59: 908–915.
