Methods and apparatus for MRI
AssigneeThe Brigham and Women's Hospital, Inc.
InventorsMirko I. Hrovat, Samuel Patz, Yuly M. Pulyer
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Abstract
Apparatus and methods for performing MRI are disclosed wherein the encoding field has a multidimensional, preferably periodic, dependence. Two dimensional image information can be obtained without the necessity for switching the encoding field. Further, velocity information can be obtained. Preferred coil structures for providing preferred encoding fields are described.
Claims26
Apparatus for obtaining image formation information from an object, said apparatus comprising:
- a magnet system for applying a magnetic field that is substantially homogeneous over an imaging space in which at least a portion of the object to be imaged is placed;
- an excitation system for applying radio frequency excitation to the object in the imaging space;
- a receiver system for detecting NMR signals from the object;
- and
- a magnetic field encoding system to apply an encoding magnetic field in the imaging space to provide spatial discrimination of the NMR signals from the object;
- wherein the encoding magnetic field comprises a field, the strength of which varies depending on more than one orthogonal spatial coordinate.
Apparatus for obtaining image formation information from an object, said apparatus comprising:
- a magnet system for applying a magnetic field that is substantially homogeneous over an imaging space in which at least a portion of the object to be imaged is placed;
- an excitation system for applying radio frequency excitation to the object in the imaging space;
- a receiver system for detecting NMR signals from the object;
- and
- a magnetic field encoding system to apply an encoding magnetic field in the imaging space to provide spatial discrimination of the NMR signals from the object;
- wherein the encoding magnetic field comprises a field, the strength of which varies in a periodic manner with respect to one spatial direction.
A method for obtaining MRI images, said method comprising:
- subjecting at least a portion of an object in an imaging space to a substantially homogeneous magnetic field;
- applying in a controlled time sequence a radio frequency field and an encoding magnetic field to spatially encode NMR signals;
- detecting the spatially encoded NMR signals;
- and
- reconstructing an image of at least a portion of the object in the imaging space based on the information in the spatially encoded NMR signals;
- wherein the method further comprises providing a encoding magnetic field, the strength of which varies with more than one orthogonal spatial coordinate.
A method for obtaining MRI images, said method comprising:
- subjecting at least a portion of an object in an imaging space to a substantially homogeneous magnetic field;
- applying in a controlled time sequence a radio frequency field and an encoding magnetic field to spatially encode NMR signals;
- detecting the spatially encoded NMR signals;
- and
- reconstructing an image of at least a portion of the object in the imaging space based on the information in the spatially encoded NMR signals;
- wherein the method further comprises providing a encoding magnetic field, the strength of which varies in a periodic manner with respect to one spatial direction.
A method for obtaining two-dimensional MRI image information in one signal acquisition interval without switching the encoding field, said method comprising:
- providing an MRI imaging system having an encoding magnetic field, the strength of which varies in more than one orthogonal spatial direction, thereby spatially encoding NMR signals in two dimensions during one signal acquisition interval and collecting two dimensional information in one such interval without switching.
A method for obtaining MRI image information from an object, said method comprising obtaining two dimensional information in one signal acquisition interval (a) by placing the object in a substantially homogeneous magnetic field (B.sub.o) and (b) by subjecting the object to an encoding magnetic field (1) having a first encoding field component that varies periodically in a first spatial direction and varies substantially linearly in a second spatial direction orthogonal to the first spatial direction and (2) having a second encoding field component that varies substantially linearly in the first spatial direction, thereby spatially encoding nuclear spins in two dimensions, and collecting the two dimensional information in one signal acquisition interval.
Dependencies are inferred from the claim text.