Rapid polarizing field cycling in magnetic resonance imaging

We describe the electronics for controlling the independently pulsed polarizing coil in a prepolarized magnetic resonance imaging (PMRI) system and demonstrate performance with free induction decay measurements and in vivo imaging experiments. A PMRI scanner retains all the benefits of acquiring MRI data at low field, but with the higher signal of the polarizing field. Rapidly and efficiently ramping the polarizing coil without disturbing the data acquisition is one of the major challenges of PMRI. With our modular hardware design, we successfully ramp the 0.4-T polarizing coil of a wrist-sized PMRI scanner at up to 100 T/s without causing image artifacts or otherwise degrading data acquisition.

[1]  A Macovski,et al.  Resistive homogeneous MRI magnet design by matrix subset selection , 1999, Magnetic resonance in medicine.

[2]  Albert Macovski,et al.  MR Imaging with T1 Dispersion Contrast , 2006 .

[3]  M. Hatridge,et al.  SQUID-detected in vivo MRI at microtesla magnetic fields , 2005, IEEE Transactions on Applied Superconductivity.

[4]  Leon Kaufman,et al.  Switched-field magnetic resonance imaging , 1992, Medical Imaging.

[5]  A Macovski,et al.  Novel approaches to low‐cost MRI , 1993, Magnetic resonance in medicine.

[6]  D Melville,et al.  Solenoid Magnet Design , 1970 .

[7]  J M Hutchison,et al.  Design, construction and use of a large-sample field-cycled PEDRI imager , 1998 .

[8]  J. Schenck.  The role of magnetic susceptibility in magnetic resonance imaging: MRI magnetic compatibility of the first and second kinds. , 1996, Medical physics.

[9]  Gareth R Davies,et al.  Field-cycled PEDRI imaging of free radicals with detection at 450 mT. , 2005, Magnetic resonance imaging.

[10]  David J. Lurie,et al.  Recent Developments in Field-Cycling MRI – Free Radicals and Quadrupole Dips , .

[11]  M A Bernstein,et al.  Artifacts induced by concomitant magnetic field in fast spin‐echo imaging , 1998, Magnetic resonance in medicine.

[12]  P. Lauterbur,et al.  The sensitivity of the zeugmatographic experiment involving human samples , 1979 .

[13]  A Macovski,et al.  A readout magnet for prepolarized MRI , 1996, Magnetic resonance in medicine.

[14]  Warner Fite,et al.  Precision High Speed Current Regulators for Occasionally Switched Inductive Loads , 1968 .

[15]  Constantin Job,et al.  Fast field‐cycling nuclear magnetic resonance spectrometer , 1996 .

[16]  G. Schauer,et al.  NMR field cycling with a superconducting magnet , 1987 .

[17]  F. Noack,et al.  NMR field-cycling spectroscopy: principles and a]lications , 1986 .

[18]  Martin Blanz,et al.  A fast field-cycling NMR/NQR spectrometer , 1993 .

[19]  H. Wallman,et al.  A Low-Noise Amplifier , 1948, Proceedings of the IRE.

[20]  Albert Macovski,et al.  Gradient Design with Arbitrary Geometrical Constraints by Linear Programming , 1999 .

[21]  T. Foster,et al.  A review of normal tissue hydrogen NMR relaxation times and relaxation mechanisms from 1-100 MHz: dependence on tissue type, NMR frequency, temperature, species, excision, and age. , 1984, Medical physics.

[22]  J W Carlson,et al.  MR relaxometry imaging. Work in progress. , 1992, Radiology.

[23]  A. Bielecki,et al.  Zero-field NMR and NQR spectrometer , 1986 .

[24]  E. Rommel,et al.  A powerful NMR field-cycling device using GTOs and MOSFETs for relaxation dispersion and zero-field studies , 1986 .