Universitaetsklinikum Freiburg

University of Pennsylvania

Walter Witschey

Maxim Zaitsev

Gerrit Schultz

Daniel Gallichan

Ravinder Reddy

Juergen Hennig

Jürgen Hennig

Ari Borthakur

A method to compensate for the magnetic field heterogeneity inside an object of investigation in a MR device obtains an uncorrected magnetic field distribution of the object and executes an MR sequence with a desired k-space coverage by applying RF pulses to generate a transverse magnetization within the object. MR signal data is recorded, magnetic field shimming parameters are dynamically updated and MR signal data are reconstructed to produce images or localized spectroscopic data. Artifacts in a reconstructed image resulting from an uncorrected magnetic field distribution are suppressed by temporally separating MR signals originating from at least two different sub-volumes within a volume of transverse magnetization by generating a nonlinear phase distribution within the object and by dynamically updating shimming parameters to compensate for the field inhomogeneity distributions within the different sub-volumes in the volume of transverse magnetization.

Method of dynamically compensating for magnetic field heterogeneity in magnetic resonance imaging

A method of MR with spatial encoding to generate an image or spectroscopic data of an object of investigation inside an MR apparatus comprises the steps of (a) selecting a volume of interest within the object of investigation, (b) applying an RF pulse to generate a transverse magnetization within the object of investigation, (c) preparing a nonlinear phase distribution within the object of investigation by application of spatially encoding magnetic fields (SEMs), the SEMs comprising of a nonlinear gradient field or a combination of linear and nonlinear gradient fields, (d) effecting primary spatial encoding through application of SEMs, and (e) recording MR signals originating from the object of investigation. Step (c) or (d) thereby comprises applying a sequence of at least two SEMs, at least one of which contains a nonlinear field gradient and at least two of the SEMs having different field geometries. The sequence of SEMs is applied at a point in time from and including the excitation of the object of interest in step (b) up to and including the recording of the MR signals in step (e), to thereby introduce a temporal shift of the signals arising from spatially different locations within the selected volume of interest, that is to thereby introduce a shift of local spatial frequency components. A sampling window for recording of the respective MR signals is set and signals originating from the volume of interest are recorded in step (e) and undesired signals originating from outside the volume of interest are suppressed.

Method of MR (=magnetic resonance) with spatial encoding to generate an image or spectroscopic data

Methods of, and systems for, magnetic resonance imaging of diagnostic mapping of tissues, where sodium mapping is performed individually, as well as in combination with other images of tissue, such as T1&#x3c1;, T2, and/or T1-weighted images. In one method embodiment, a sodium image of the tissue is acquired during the same scanning session. Maps are constructed of each of the first and sodium images individually, and in combination, and further facilitate viewing in combination with each other as a single, blended image of the tissue. Maps of the images may be displayed individually or in combination with each other.

Magnetic resonance imaging for diagnostic mapping of tissues

Growing community of inventors

Philadelphia, PA, United States of America

Walter Witschey