Leland Stanford Junior University

University of California

Charles H Cunningham

John Mark Pauly

Steven M Conolly

Michael Lustig

Daniel Blackburn Vigneron

Brian A Hargreaves

Graham Arnold Wright

Krishna S Nayak

John Andrew Derbyshire

Jeffrey Alan Stainsby

Juan Manuel Santos

Albert P Chen

A computer implemented method for designing a spectral-spatial pulse for exciting at least one passband and minimally exciting at least one stopband is provided. A uniform shaped spectral envelope is generated. For a plurality of k&#x2260;0, kdependent weights for a spectral envelope that approximate a k=0 envelope and provides the at least one passband and the at least one stopband for each of the plurality of k&#x2260;0 is generated.

Optimized spectral-spatial pulse

Off-resonance imaging uses two complementary contrast agents with the first agent (iron-oxide) particles transfected into cells which provide localized signals. The second agent is detected from a change in the off-resonance signal when present in the cells labeled by the first agent.

Method of off-resonance detection using complementary MR contrast agents

A method for magnetic resonance imaging (MRI) is provided. A magnetic resonance excitation is provided. A magnetic field is read out through k-space using winders, wherein some of the winders overlap for a length of the winders. Readout data from overlapping lengths of winders is used to estimate motion. The readout may use a two dimensional discrete Fourier transform acquisition.

Self navigating cartesian trajectory

Contrast agents incorporating super-paramagnetic iron-oxide (SPIO) nanoparticles have shown promise as a means to visualize labeled cells using MRI. Labeled cells cause significant signal dephasing due to the magnetic field inhomogeneity induced in water molecules near the cell. With the resulting signal void as the means for detection, the particles are behaving as a negative contrast agent, which can suffer from partial-volume effects. Disclosed is a new method for imaging labeled cells with positive contrast. Spectrally-selective RF pulses are used to excite and refocus the off-resonance water surrounding the labeled cells so that only the fluid and tissue immediately adjacent to the labeled cells are visible in the image. Phantom, in vitro, and in vivo experiments show the feasibility of the new method. A significant linear correlation (r=0.87, p&#x3c;0.005) between the estimated number of cells and the signal has been observed.

Positive contrast MRI of magnetically tagged cells, objects, tissues

For in vivo magnetic resonance imaging at high field (&#x2267;3 T) it is essential to consider the homogeneity of the active Bfield (B+), particularly if surface coils are used for RF transmission. A new method is presented for highly rapid B+ magnitude mapping. It combines the double angle method with a B-insensitive magnetization-reset sequence such that the choice of repetition time (TR) is independent of Tand with a multi-slice segmented (spiral) acquisition to achieve volumetric coverage with adequate spatial resolution in a few seconds.

RF field mapping for magnetic resonance imaging

A pulse sequence for use in steady state free precession (SSFP) imaging sequences includes a RF pulse and a time-varying gradient pulse based on a conventional design algorithm such as the Shinnar-LeRoux (SLR) pulse design algorithm and in which amplitude of the RF pulse and gradient pulse are increased while pulse time is decreased thereby reducing imaging time and improving slab profiles.

Reduced-time variable rate excitation pulses for rapid MRI

A method for designing non-linear phase 180&#xb0; spectral-spatial radio frequency pulses that can be used for spectral editing in magnetic resonance spectroscopic imaging. A novel feature of the pulse is a symmetric sweep developed by the spectral profile from the outside edges of the spectral window towards the middle whereby coupled components are tipped simultaneously and over a short interval. Pulses have been designed for lactate editing at 1.5T and 3T. The spectral and spatial spin-echo profiles of the RF pulses can be measured experimentally and altered in an iterative manner. Spectral-spatial radio frequency (SSRF) pulses allow simultaneous selection in both frequency and spatial domains. These pulses are particularly important for clinical and research magnetic resonance spectroscopy (MRS) applications for suppression of large water and lipid resonances.

Non-linear symmetric sweep spectral-spatial RF pulses for MR spectroscopy

A RF Excitation pulse for MRI applications has built-in saturation sidebands, thereby reducing the time for an excitation sequence. The pulse is created using the Shinnar-Le Roux (SLR) transform and designing beta-polynomials for a desired image slice excitation and for saturation of RF excitation such as by de-phasing in regions adjacent to the desired image slice. The beta-polynomials are combined and an inverse SLR transform creates the RF pulse from the combined beta-polynomial.

Growing community of inventors

San Francisco, CA, United States of America

Charles H Cunningham