Method for visualizing charged particle motion using magnetic resonance imaging
AssigneeMayo Foundation for Medical Education
InventorsRaja Muthupillai, Richard L. Ehman
Life of this patent
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Abstract
A scan using an NMR imaging system is carried out while applying an oscillating voltage to the subject being imaged. The applied voltage may produce an electric field which moves charged particles in the subject, or it may produce a current that moves ions in the subject. An alternating magnetic field gradient synchronized with the applied voltage is employed in the NMR imaging pulse sequence to detect and measure synchronous spin motion throughout the field of view. The direction of the alternating gradient and/or the applied voltage may be changed to measure and image the properties of the subject.
Claims12
An NMR method for producing an image indicative of synchronous spin motion in a subject including charged particles, the steps comprising:
- a) applying a polarizing magnetic field to the subject;
- b) irradiating the subject with an RF excitation field that produces transverse magnetization in spins in said subject;
- c) applying a magnetic field gradient to the spins which alternates in polarity;
- d) applying a voltage to the subject which varies in magnitude in synchronism with the alternation in the magnetic field gradient polarity to produce an oscillating electric field in the subject that interacts with charged particles in the subject to produce oscillating motion of the charged particles, where the charged particles produce a stress directly on surrounding material in the subject;
- e) acquiring an NMR signal produced by the transversely magnetized spins;
- f) repeating steps a) through e) to acquire a set of said NMR signals from which an image may be reconstructed;
- and
- g) reconstructing a phase image from said set of NMR signals.
A method for producing an NMR image of the motion of charged particles in a medium, the steps comprising:
- applying an oscillating electric field to a medium comprising charged particles which interacts with the charged particles in the medium to produce oscillatory motion of charged particles in the medium directly;
- applying an rf excitation pulse that produces transverse magnetization of spins in the medium;
- acquiring an NMR image data set using a pulse sequence that employs an alternating magnetic field gradient that is synchronized with the oscillating electric field and oscillatory motion of spins in the medium;
- acquiring an NMR signal from said transversely magnetized spins;
- and
- reconstructing a phase image from the NMR image data set in which each pixel in the phase image indicates the spins moving with said oscillatory motion at a corresponding location in the subject, providing an image of the oscillatory motion of the charged particles.
A method for producing an NMR image of a subject with an MR imaging system, the steps comprising:
- applying an oscillating current to the subject which interacts with ions in the subject to produce oscillatory motion of ions in the subject, the oscillatory motion of the ions producing shear waves in the subject directly;
- applying an RF excitation pulse that produces transverse magnetization in spins in the subject;
- acquiring an NMR image data set using a pulse sequence that employs an alternating magnetic field gradient that is synchronized with oscillatory motion of spins in the subject;
- acquiring an NMR signal from said transversely magnetized spins;
- and
- reconstructing a phase image from the NMR image data set in which each pixel in the phase image indicates the spins moving with said oscillatory motion at a corresponding location in the subject.
Dependencies are inferred from the claim text.