Vanderbilt University

Northwestern University

Mark Does

John A Rogers

William Allyn Grissom

Robert Adam Horch

Daniel Frank Gochberg

Zhipeng Cao

Jeffrey S Nyman

Kevin Harkins

Accurate measurement of gradient waveform errors can often improve image quality in sequences with time varying readout and excitation waveforms. Self-encoding or offset-slice method sequences are commonly used to measure gradient waveforms. However, the self-encoding method requires a long scan time, while the offset-slice method is often low precision, requiring the thickness of the excited slice to be small compared to the maximal k-space encoded by the test waveform. This disclosure describes a novel hybrid of those methods, referred to as variable-prephasing (VP). Like the offset-slice method, VP uses the change in signal phase from offset-slices to calculate the gradient waveform. Similar to the self-encoding method, repeated acquisitions with a variable amplitude self-encoding gradient mitigates the signal loss due to phase wrapping, which, in-turn, allows thicker slices and greater SNR.

Efficient gradient waveform measurements with variable prephasing

An implantable bioresorbable radio frequency (RF) coil for high-resolution and high-specificity post-surgical evaluating or monitoring with magnetic resonance imaging (MRI) is disclosed. The coil includes a bioresorbable conductor configured to be resorbed within a patient while the coil is implanted in the patient. In one embodiment, the target application of this coil is the evaluation or monitoring (via MRI) of peripheral nerve regeneration following surgical repair.

Bioresorbable RF coils for post-surgical monitoring by MRI

Systems and methods for performing MRI include using a RF gradient field for spatial encoding. In particular implementations, |B|-selective pulses designed using the Shinnar-Le Roux algorithm can be provided as the excitation pulse for the RF gradient field. Further, frequency encoding for the RF gradient field can be based on the Bloch-Siegert (BS) shift. Together, these techniques can be used to support MRI based on RF gradient encoding instead of the conventional Bo encoding.

MRI using RF gradients for spatial encoding

Systems and methods for characterizing bone structures are provided for characterizing bone structures. In the system and method, one or moreH NMR or MRI signals associated with a bone structure are obtained. Thereafter one or more signal parameters are computed from the obtained signals, where each of the signal parameters comprising at least one of a relaxation rate constant or a corresponding signal amplitude associated with a component of the obtained signals defined by a Tvalue or a range of Tvalues. Finally, the mechanical properties or fracture risk for the bone structure are determined based on the computed signal parameters and stored correlation data.

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Nashville, TN, United States of America

Mark Does