Leland Stanford Junior University

General Electric Company

Daniel Mark Spielman

John Mark Pauly

Priti Balchandani

Elfar Adalsteinsson

Norbert Joseph Pelc

Albert Macovski

Craig H Meyer

Gary H Glover

Ralph Eugene Hurd

Yakir Levin

Dong-Hyun Kim

Edith V Sullivan

Dirk Mayer

Adolf Pfefferbaum

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 (F(&#x3c9;)) 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(&#x3c9;), wherein the applying the quadratic phase comprises setting F(&#x3c9;)=F(&#x3c9;)e. A polynomial &#x3b2; is set to equal a Fourier Transform (F(&#x3c9;)). A corresponding minimum phase &#x3b1; polynomial is determined for the &#x3b2; polynomial. (&#x3b1;,&#x3b2;) 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&#x3e;0.03&#x3c0;/(&#x3c9;&#x2212;&#x3c9;)/(N+1) and k&#x3c;k, where kis a value at which the adiabatic RF pulse is truncated at 25% of a maximum RF amplitude.

Algorithm for adiabatic pulse design using the Shinnar Le-Roux transform

A method for performing spectroscopy using an interleaved readout for at least two species. A Bfield is applied. A first spatial-spectral (SPSP) position resolved spectroscopy sequence (PRESS) excitation with a sufficiently narrow band to excite a first species without exciting a second species is applied. A first readout that measures the first species is performed. A second SPSP PRESS excitation with a sufficiently narrow band to excite the second species without exciting the first species is applied. A second readout that measures the second species is performed.

Method for magnetic resonance spectroscopic imaging

A method for frequency selective and slice selective magnetic resonance imaging (MRI) is provided. A Bfield is applied. A self-refocused spatial-spectral (SPSP) RF pulse is applied. A readout of a portion of k-space for the excited slice is performed. A second self-refocused SPSP excitation RF pulse is applied, wherein the second self-refocused SPSP excitation has an 180&#xb0; echo phase difference from the self-refocused SPSP excitation. A second readout of a portion of k-space for the excited slice was performed. A difference between the readout and the second readout was found. The previous steps were repeated until k-space has been filled for the excited slice. The previous steps were repeated for a plurality of slices.

Self-refocused spatial-spectral pulse

A method of imaging the individual components of systems with sparse spectra using magnetic resonance imaging including the steps of a) exciting nuclei of labeled components using a MRI pulse sequence, b) selecting a proper spectral window to avoid/minimize signal overlap of aliased frequency components. In step a) preferably a spiral chemical shift imaging (spCSI) sequence is employed. In a preferred embodiment, hyperpolarized nuclei ofC are used for labeling in a pyruvate substrate with metabolites of lacatate, alanine, and bicarbonate.

Fast metabolic imaging of systems with sparse spectra using spiral CSI

A manifestation of the invention provides a method for slice selective excitation for magnetic resonance imaging (MRI). A Bfield is applied. A STABLE pulse comprising of a BIR-4 envelope sampled by a plurality of subpulses with a duration is applied, where amplitude and frequency modulation functions of the BIR-4 envelope are slowly varying with respect to the duration of the subpulses. A portion of k-space is read out to obtain k-space data. The STABLE pulse and readout are repeated until sufficient k-space has been acquired. A Fourier Transform of the k-space data is taken.

Slice-selective tunable-flip adiabatic low peak power excitation

A non-invasive longitudinal method that is sensitive and objective for quantifying progressive loss of neurons in normal aging brains and brains that suffer from a neurodegenerative disease is provided. The method also provides clinicians, patients and drug companies with a method for evaluating the efficacy of various treatments and interventions by assessing a change in brain integrity. The method determines and localizes a change in brain integrity in a compartment of a brain from at least structural images and metabolite brain images, which are acquired for at least two time instances. The time period between two time instances is dependent on the disease pathology and disease progression and could, for instance, be at least 3 months between time instances as well as at least 6 or 12 months between time instances.

Magnetic resonance spectroscopic imaging method to monitor progression and treatment of neurodegenerative conditions

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 B 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.

High order shimming of MRI magnetic fields using regularization

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. Further, off-resonance effects can be placed in sidelobes of the spin-echo signal to facilitate suppression in the detected signals.

Apparatus and method for rare echo imaging using k-space spiral coverage

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.

Growing community of inventors

Menlo Park, CA, United States of America

Daniel Mark Spielman