The Johns Hopkins University

National Institutes of Health, a Component of the US Dept. of Health & Human Services

The United States of America As Represented by the Department of Health

Ronald Ouwerkerk

Reza Nezafat

Matthias Stuber

Elliot R McVeigh

J Andrew Derbyshire

A magnetic resonance imaging (MRI) system, comprising: a magnetic resonance imaging scanner comprising: a main magnet providing a substantially uniform main magnetic field B0 for a subject under observation; and a radio frequency (RF) coil configured to irradiate a radio frequency (RF) pulse into a region of interest of the subject under observation, wherein the RF pulse comprises a base pulse comprising an adiabatic pulse having a first bandwidth time product (BWTP), wherein the RF pulse selectively suppresses magnetic resonance signals from more than one chemical component or more than one spatial region within the region of interest of the subject under observation, and wherein the adiabatic pulse is characterized by an amplitude modulation function and a frequency modulation function.

Adiabatic multi-band RF pulses for selective signal suppression in a magnetic resonance imaging

Adiabatic pulses that define an amplitude modulation and a frequency modulation are applied in a sequence of pulses to obtain a Tweighted magnetic resonance image. Such an adiabatic Tprep sequence typically includes a first 90&#xb0; pulse, an even number of adiabatic pulses, and a second 90&#xb0; pulse. Adiabatic pulses can be selected based on function pairs, or can be defined numerically. A magnetic resonance imaging (MRI) system includes a library of adiabatic pulse waveforms, and is configured to select a waveform and apply an RF magnetic field based on the selected pulse waveform.

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A Tpreparation sequence uses a segmented BIR-4 adiabatic pulse with two substantially equal delays and is insensitive to Bfield variations and can simultaneously suppress fat signals with low specific absorption rate (SAR). An adiabatic reverse half passage pulse is applied followed by a predetermined delay. An adiabatic full passage pulse is applied followed by a substantially equal delay, followed by an adiabatic half passage pulse. Fat signal suppression is achieved by increasing or decreasing either the first delay or the second delay.

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Ronald Ouwerkerk