Broadband proton decoupling for in vivo brain spectroscopy in humans

A new decoupling sequence, PBAR, is described for broadband heteronuclear decoupling in vivo in humans at 1.5T. The sequence uses non‐adiabatic, frequency‐ and amplitude‐modulated inversion pulses designed to minimize decoupling sidebands at low applied γB2 RF field levels and to cover only the narrow range of resonance offsets encountered in practice. The offset dependence of the decoupling efficiency of PBAR is demonstrated and compared to the conventional WALTZ‐4 sequence. At the same average power levels, PBAR had slightly reduced bandwidth but significantly less intense decoupling sidebands. Applications of PBAR are shown in vivo in the human brain both for 31P and natural abundance 13C spectroscopy using volume decoupling coils. The PBAR sequence allows whole brain {1H}‐13C decoupling to be performed at 1.5T with a standard head coil within FDA guidelines for RF power deposition. Magn Reson Med 45:226–232, 2001. © 2001 Wiley‐Liss, Inc.

[1]  S. Blüml,et al.  Developmental changes in choline‐ and ethanolamine‐containing compounds measured with proton‐decoupled 31P MRS in in vivo human brain , 1999, Magnetic resonance in medicine.

[2]  S. Bluml.  In VivoQuantitation of Cerebral Metabolite Concentrations Using Natural Abundance13C MRS at 1.5 T , 1999 .

[3]  S. Blüml.  In vivo quantitation of cerebral metabolite concentrations using natural abundance 13C MRS at 1.5 T. , 1999, Journal of magnetic resonance.

[4]  Z. Bhujwalla,et al.  Malignant transformation alters membrane choline phospholipid metabolism of human mammary epithelial cells. , 1999, Cancer research.

[5]  C. Collins,et al.  A numerical study of radiofrequency deposition in a spherical phantom using surface coils. , 1998, Magnetic resonance imaging.

[6]  M. Cabanac.  Selective Brain Cooling and Thermoregulatory Set-Point , 1998, Journal of basic and clinical physiology and pharmacology.

[7]  Kupce.  Effect of sweep direction on sidebands in adiabatic decoupling , 1997, Journal of magnetic resonance.

[8]  M. Garwood,et al.  Reduction of sideband intensities in adiabatic decoupling using modulation generated through adiabatic R-variation (MGAR) , 1996 .

[9]  Ray Freeman,et al.  Adiabatic pulses for wideband inversion and broadband decoupling , 1995 .

[10]  M. Bendall.  Broadband and Narrowband Spin Decoupling Using Adiabatic Spin Flips , 1995 .

[11]  Z. Starcuk,et al.  Heteronuclear Broadband Spin-Flip Decoupling with Adiabatic Pulses , 1994 .

[12]  R. Gruetter,et al.  Direct measurement of brain glucose concentrations in humans by 13C NMR spectroscopy. , 1992, Proceedings of the National Academy of Sciences of the United States of America.

[13]  U. Keller,et al.  13C NMR for the assessment of human brain glucose metabolism in vivo. , 1991, Biochemistry.

[14]  R. Dykstra.  A method to suppress cycling sidebands in broadband decoupling , 1989 .

[15]  P R Luyten,et al.  Broadband proton decoupling in human 31p NMR spectroscopy , 1989, NMR in biomedicine.

[16]  P. Röschmann.  Radiofrequency penetration and absorption in the human body: limitations to high-field whole-body nuclear magnetic resonance imaging. , 1987, Medical physics.

[17]  A. J. Shaka,et al.  Three-spin effects in broadband decoupling , 1987 .

[18]  A. J. Shaka,et al.  Broadband spin decoupling in isotropic-liquids , 1987 .

[19]  A. J. Shaka,et al.  Cycling sidebands in broadband decoupling , 1986 .

[20]  Roger J. Ordidge,et al.  Image-selected in Vivo spectroscopy (ISIS). A new technique for spatially selective nmr spectroscopy , 1986 .

[21]  A. J. Shaka,et al.  Homonuclear Hartmann-Hahn effects in broadband decoupling , 1985 .

[22]  A. J. Shaka,et al.  Computer-optimized decoupling scheme for wideband applications and low-level operation , 1985 .

[23]  A. J. Shaka,et al.  Evaluation of a new broadband decoupling sequence: WALTZ-16 , 1983 .

[24]  W. S. Veeman,et al.  Broadband heteronuclear decoupling , 1983 .

[25]  R. R. Ernst.  Nuclear Magnetic Double Resonance with an Incoherent Radio‐Frequency Field , 1966 .

[26]  W. A. Anderson,et al.  Removal of Residual Splitting in Nuclear Magnetic Double Resonance , 1963 .