Leland Stanford Junior University

Priti Balchandani

John Mark Pauly

Daniel Mark Spielman

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 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.

Growing community of inventors

Menlo Park, CA, United States of America

Priti Balchandani