Abstract: A method for providing an adiabatic RF pulse that is an inversion or refocusing pulse for a RF pulse sequence is provided. A linear phase frequency profile (Flp(?)) is determined for the adiabatic RF pulse. A quadratic phase is applied to the linear phase frequency profile for the adiabatic RF pulse to obtain F(?), wherein the applying the quadratic phase comprises setting F(?)=Flp(?)eik?2. A polynomial ? is set to equal a Fourier Transform (F(?)). A corresponding minimum phase ? polynomial is determined for the ? polynomial. (?,?) are set as inputs to an inverse Shinnar Le-Roux transform to generate an adiabatic RF waveform. The adiabatic RF waveform is truncated to produce the adiabatic RF pulse, wherein k>0.03?/(?5??p)/(N+1) and k<kmax, where kmax is a value at which the adiabatic RF pulse is truncated at 25% of a maximum RF amplitude.

Abstract: The invention relates to a method of 13C-MR imaging, 13C-MR spectroscopy and/or 13C-MR spectroscopic imaging of inflammation or infection using an imaging medium which comprises a hyperpolarized 13C-substance.

Abstract: A method for providing an adiabatic RF pulse that is an inversion or refocusing pulse for a RF pulse sequence is provided. A linear phase frequency profile (Flp(?)) is determined for the adiabatic RF pulse. A quadratic phase is applied to the linear phase frequency profile for the adiabatic RF pulse to obtain F(?), wherein the applying the quadratic phase comprises setting F(?)=Flp(?)eik?2. A polynomial ? us set ti equal a Fourier Transform (F(?)). A corresponding minimum phase ? polynomial is determined for the ? polynomial. (?,?) are set as inputs to an inverse Shinnar Le-Roux transform to generate an adiabatic RF waveform. The adiabatic RF waveform is truncated to produce the adiabatic RF pulse, wherein k>0.03?/(?5??p)/(N+1) and k<kmax, where kmax is a value at which the adiabatic RF pulse is truncated at 25% of a maximum RF amplitude.

Abstract: Disclosed is a method for regularized high-order shimming of a magnetic field in an MRI system. In one application a spiral pulse sequence is used to acquire field maps, and based on the user selection a shimming region, a least squares calculation of shim currents is performed that minimizes the root mean square (RMS) value of the B0 in homogeneity-over the volume of interest. The singular value decomposition (SVD) is used to enable regularized methods for solving the least squares problem. The regularization allows arbitrary regions to be shimmed without the divergence of shim currents.

Abstract: A long train of spin echoes is produced using a RARE excitation pulse sequence, and during each spin echo an annular segment of a long k-space spiral as determined by read-out magnetic gradients is detected. At the end of the echo train the entire k-space spiral will have been covered. Each of the segments can be a unique annular portion of the k-space spiral. Alternatively, fewer annular segments of the spiral can be provided, with the fewer annular segments rotated in k-space and replayed to cover interleaved paths in k-space. The imaging gradients are refocused at the time of each spin-echo pulse in order to permit the long echo pulse trains of RARE imaging. Each spiral segment is surrounded by gradient lobes that move out from the k-space origin to the beginning of the segment, and move back to the origin from the end of the segment. Advantageously, the magnetic gradient lobes can be produced concurrently with parasitic echo crusher gradients at the beginning and end of each spin-echo pulse.

Abstract: A new pulse sequence which uses inversion recovery for lipid suppression and a spectral-spatial refocusing pulse for water suppression in spectroscopic imaging of the brain. In contrast to methods which eliminate fat by restricting the excited volume to lie completely within the brain, inversion recovery techniques allow imaging of an entire slice without such restrictions. A spectral-spatial pulse provides water suppression insensitive to a reasonable range of B.sub.0 and B.sub.1 inhomogeneities. Metabolite maps covering large volumes of the human brain can be produced with images from single and multiple slices obtained.