Magnetic resonance imaging system with thin cylindrical uniform field volume and moving subjects

Claim 2

A magnetic resonance apparatus comprising: a patient receiving sleeve; a thin main field magnet disposed around the patient receiving sleeve defining a thin imaging volume having a height, a width, and a thickness, which imaging volume thickness is (i) at least twice a slice thickness, (ii) less than 15 cm thick, and (iii) smaller than the imaging volume height and width; said magnet generating a main magnetic field which is uniform and temporally constant within said thin imaging volume which is transverse to a central axis of the patient receiving sleeve, which thin imaging volume is thin in a direction parallel to the axis of the patient receiving sleeve; a radio frequency coil disposed around the thin imaging volume; a patient support and transport means for supporting a patient and moving the patient axially, transverse to and through the thin imaging volume during a magnetic resonance examination.

Claim 3

The apparatus as set forth in claim 1 further including a gradient coil assembly disposed around the radio frequency coil for creating gradient magnetic fields along orthogonal directions in the thin imaging volume.

Claim 4

The apparatus as set forth in claim 2 further including: a magnetic resonance imaging sequence memory and control means for designating magnetic field gradient and radio frequency pulses of a selected magnetic resonance imaging sequence; a radio frequency transmitter connected with the sequence memory and control means and the radio frequency coil for transmitting the designated radio frequency pulses into the thin imaging volume; a gradient field control means connected with the sequence memory and control means and the gradient coil assembly for causing the gradient coil assembly to create the gradient magnetic fields in the thin imaging volume; a radio frequency receiver for receiving radio frequency signals from the thin imaging volume and demodulating the received signals into electronic views; a reconstruction means for reconstructing the views into a three-dimensional image representation; an image memory for storing the three-dimensional image representation.

Claim 5

The apparatus as set forth in claim 1 further including an thin imaging volume locating means for moving the patient receiving sleeve, the main field magnet, and the radio frequency coil for relocating the thin imaging volume.

Claim 6

The apparatus as set forth in claim 1 wherein the patient support and transport means includes a patient supporting surface, a carriage, and a plurality of wheels such that the patient supporting surface and carriage can be wheeled from place to place, whereby one patient can be prepared for the examination in a remote location while another patient is being examined and whereby the patient can be moved without repreparation from one diagnostic apparatus to another.

Claim 7

The apparatus as set forth in claim 1 wherein the main field magnet includes a permanent magnet having oppositely disposed pole faces of substantially the width of the thin imaging volume such that the thin imaging volume is defined therebetween.

Claim 8

A magnetic resonance apparatus comprising: a patient receiving sleeve; a main field magnet disposed around the patient receiving sleeve for generating a temporally constant main magnetic field within an examination volume which is thin in a direction parallel to the axis of the patient receiving sleeve; a radio frequency coil disposed around the examination volume; a patient support and transport means for supporting a patient and moving the patient axially through the examination volume during a magnetic resonance examination; and a means for shifting an image slice relative to a coordinate system of the main field magnet in coordination with movement of the patient by the patient support and transport means.

Claim 9

A magnetic resonance apparatus comprising: a patient receiving sleeve; a main field magnet disposed around the patient receiving sleeve for generating a temporally constant main magnetic field within an examination volume which is thin in a direction parallel to the axis of the patient receiving sleeve; a radio frequency coil disposed around the examination volume; a patient support and transport means for supporting a patient and moving the patient axially through the examination volume during a magnetic resonance examination; and a means for shifting an image slice relative to a coordinate system of the main field magnet in coordination with movement of the patient by the patient support and transport means.

Claim 10

The apparatus as set forth in claim 7 further including active gradient shield coils disposed around the gradient coil assembly, the gradient coil assembly and the active gradient shield coil assembly acting together to (1) create the magnetic field gradients in the examination volume and (2) to cancel magnetic field gradients outside of the examination volume.

Claim 11

A magnetic resonance imaging apparatus comprising: a patient receiving sleeve; a main field magnet disposed around the patient receiving sleeve for generating a main magnetic field with is temporally constant within an examination volume which is thin in a direction parallel to the axis of the patient receiving sleeve; a radio frequency coil disposed around the examination volume; a gradient coil assembly disposed around the radio frequency coil for creating gradient magnetic fields along the orthogonal directions in the examination volume; a patient support and transport for supporting a patient and moving the patient axially through the examination volume during a magnetic resonance examination; a magnetic resonance imaging sequence memory and control for designating magnetic field gradient and radio frequency pulses of a selected magnetic resonance imaging sequence; a gradient field control connected with the sequence memory and control and the gradient coil assembly for causing the gradient coil assembly to create the gradient magnetic fields in the examination volume, the gradient field control causing the gradient coils to apply at least slice select gradients along the patient receiving sleeve axis; a radio frequency receiver for receiving radio frequency signals from the examination volume and demodulating the received signals into electronic views; a radio frequency scaling control connected with the radio frequency transmitter and the radio frequency receiver for incrementing resonance frequency in accordance with movement of the patient support and transport means; a reconstruction processor for reconstructing the views into a three-dimensional image representation; an image memory for storing the three-dimensional image representation.

Claim 12

A magnetic resonance imaging apparatus comprising: a patient receiving sleeve; a main field magnet disposed around the patient receiving sleeve for generating a main magnetic field with is temporally constant within an examination volume which is thin in a direction parallel to the axis of the patient receiving sleeve; a radio frequency coil disposed around the examination volume; a gradient coil assembly disposed around the radio frequency coil for creating gradient magnetic fields along the orthogonal directions in the examination volume; a patient support and transport for supporting a patient and moving the patient axially through the examination volume during a magnetic resonance examination; a magnetic resonance imaging sequence memory and control for designating magnetic field gradient and radio frequency pulses of a selected magnetic resonance imaging sequence; a gradient field control connected with the sequence memory and control and the gradient coil assembly for causing the gradient coil assembly to create the gradient magnetic fields in the examination volume, the gradient field control causing the gradient coils to apply at least slice select gradients along the patient receiving sleeve axis; a radio frequency receiver for receiving radio frequency signals from the examination volume and demodulating the received signals into electronic views; a radio frequency scaling control connected with the radio frequency transmitter and the radio frequency receiver for incrementing resonance frequency in accordance with movement of the patient support and transport means; a reconstruction processor for reconstructing the views into a three-dimensional image representation; an image memory for storing the three-dimensional image representation.

Claim 13

The apparatus as set forth in claim 9 wherein the reconstruction processor uses a Fourier transform reconstruction technique to reconstruct a plurality of phase-encoded views corresponding to a single slice of an examined subject into a two-dimensional image representation, the sequence memory and control causing the gradient field control to index the slice select gradient to a next adjacent slice after the views for each slice have been generated, such that the three-dimensional image representation includes a series of parallel two-dimensional image representations.

Claim 14

The apparatus as set forth in claim 9 wherein the a reconstruction processor performs a projection transform reconstruction procedure to reconstruct a plurality of angularly displaced projection views corresponding to a single slice of an examined subject into a two-dimensional image representation, the sequence memory and control causing the gradient field control to index the slice select gradient to a next adjacent slice after the views for each slice have been generated, such that the three-dimensional image representation includes a series of parallel two-dimensional image representations.

Claim 15

A magnetic resonance imaging apparatus comprising: a patient receiving sleeve; a main field magnet disposed around the patient receiving sleeve for generating a main magnetic field which is uniform and temporally constant within an examination volume which is thin in a direction parallel to the axis of the patient receiving sleeve; a radio frequency coil disposed around the examination region; a gradient coil assembly disposed around the examination volume for creating gradient magnetic fields along orthogonal directions in the examination volume; a patent support and transport for supporting a patient and moving the patient axially through the examination volume during a magnetic resonance examination; a magnetic resonance imaging sequence memory and control for designating magnetic field gradient and radio frequency pulses of a selected magnetic resonance imaging sequence; a radio frequency transmitter connected with the sequence control and the radio frequency coil for transmitting the designated radio frequency pulses into the examination volume; a gradient field control connected with the sequence control and the gradient coil assembly for causing the gradient coil assembly to create the gradient magnetic fields in the examination volume; a radio frequency receiver for receiving radio frequency signals from the examination volume and demodulating the received signals into electronic views; a reconstruction processor which performs a Fourier transform reconstruction on a plurality of the views corresponding to a single slice of an examined subject into a two-dimensional image representation, the imaging sequence control causing the gradient field control to index the slice select gradient to a next adjacent slice after the views for each slice have been generated, such that a series of parallel two-dimensional image representations are generated.

Claim 16

A magnetic resonance imaging apparatus comprising: a patient receiving sleeve; a main field magnet disposed around the patient receiving sleeve for generating a main magnetic field which is uniform and temporally constant within an examination volume which is thin in a direction parallel to the axis of the patient receiving sleeve; a radio frequency coil disposed around the examination region; a gradient coil assembly disposed around the examination volume for creating gradient magnetic fields along orthogonal directions in the examination volume; a patent support and transport for supporting a patient and moving the patient axially through the examination volume during a magnetic resonance examination; a magnetic resonance imaging sequence memory and control for designating magnetic field gradient and radio frequency pulses of a selected magnetic resonance imaging sequence; a radio frequency transmitter connected with the sequence control and the radio frequency coil for transmitting the designated radio frequency pulses into the examination volume; a gradient field control connected with the sequence control and the gradient coil assembly for causing the gradient coil assembly to create the gradient magnetic fields in the examination volume; a radio frequency receiver for receiving radio frequency signals from the examination volume and demodulating the received signals into electronic views; a reconstruction processor which performs a Fourier transform reconstruction on a plurality of the views corresponding to a single slice of an examined subject into a two-dimensional image representation, the imaging sequence control causing the gradient field control to index the slice select gradient to a next adjacent slice after the views for each slice have been generated, such that a series of parallel two-dimensional image representations are generated.

Claim 17

A magnetic resonance imaging apparatus comprising: a cylindrical patient receiving sleeve; a main field magnet disposed around the patient receiving sleeve for generating a main magnetic field is uniform and temporally constant is a cylindrical examination volume at least 45 cm in diameter and less than 15 cm thick in a direction parallel to the axis of the patient receiving sleeve; a gradient coil assembly disposed around the radio frequency coil for creating gradient magnetic fields along orthogonal directions in the examination volume; a radio frequency coil disposed around the examination volume; a patient support and transport for supporting a patient and moving the patient axially through the examination volume during a magnetic resonance examination; a magnetic resonance imaging sequence control for designating magnetic field gradient and radio frequency pulses of a selected magnetic resonance imaging sequence; a radio frequency transmitter connected with the sequence control and the radio frequency coil for transmitting the designated radio frequency pulses into the examination volume; a gradient field control connected with the sequence control and the gradient coil assembly for causing the gradient coil assembly to create the gradient magnetic fields in the examination volume; a radio frequency receiver for receiving radio frequency signals from the examination volume and demodulating the received signals into electronic views; a reconstruction processor for reconstructing the views into a three-dimensional image representation; an image memory for storing the three-dimensional image representation.

Claim 18

A magnetic resonance imaging apparatus comprising: a cylindrical patient receiving sleeve; a main field magnet disposed around the patient receiving sleeve for generating a main magnetic field is uniform and temporally constant is a cylindrical examination volume at least 45 cm in diameter and less than 15 cm thick in a direction parallel to the axis of the patient receiving sleeve; a gradient coil assembly disposed around the radio frequency coil for creating gradient magnetic fields along orthogonal directions in the examination volume; a radio frequency coil disposed around the examination volume; a patient support and transport for supporting a patient and moving the patient axially through the examination volume during a magnetic resonance examination; a magnetic resonance imaging sequence control for designating magnetic field gradient and radio frequency pulses of a selected magnetic resonance imaging sequence; a radio frequency transmitter connected with the sequence control and the radio frequency coil for transmitting the designated radio frequency pulses into the examination volume; a gradient field control connected with the sequence control and the gradient coil assembly for causing the gradient coil assembly to create the gradient magnetic fields in the examination volume; a radio frequency receiver for receiving radio frequency signals from the examination volume and demodulating the received signals into electronic views; a reconstruction processor for reconstructing the views into a three-dimensional image representation; an image memory for storing the three-dimensional image representation.

Claim 19

A magnetic resonance apparatus comprising: a patient receiving sleeve; a main field magnet disposed around the patient receiving sleeve for generating a main magnetic field which is uniform and temporally constant within an examination volume which is thin in a direction parallel to the axis of the patient receiving sleeve; a radio frequency coil disposed around the examination volume; a rotating means for rotating the patient receiving sleeve, the main field magnet, and the radio frequency coil such that the examination volume is disposed in a substantially horizontal plane; and a means for moving a standing patient and the examination volume relative to each other along a vertical axis.

Claim 20

A magnetic resonance apparatus comprising: a patient receiving sleeve; a main field magnet disposed around the patient receiving sleeve for generating a main magnetic field which is uniform and temporally constant within an examination volume which is thin in a direction parallel to the axis of the patient receiving sleeve; a radio frequency coil disposed around the examination volume; a rotating means for rotating the patient receiving sleeve, the main field magnet, and the radio frequency coil such that the examination volume is disposed in a substantially horizontal plane; and a means for moving a standing patient and the examination volume relative to each other along a vertical axis.

Claim 23

The method as set forth in claim 15 wherein the step of exciting and manipulating magnetic resonance and receiving magnetic resonance signals from the selected slice includes applying a slice select gradient along a direction of subject movement and further including: shifting the selected slice relative to the imaging volume such that the selected slice remains fixed relative to the subject.

Claim 24

The method as set forth in claim 16 further including after receiving a full set of magnetic resonance signals from the selected slice for reconstruction into a two-dimensional slice image, indexing the slice select gradient to select a next adjacent slice of the subject and repeating the exciting and manipulating magnetic resonance and receiving magnetic resonance signal step and the shifting step.

Claim 25

The method as set forth in claim 17 wherein the reconstructing step includes at least one of Fourier transform reconstructing and projection reconstruction of the magnetic resonance signals into a plurality of parallel two-dimensional slice images.

Claim 26

The method as set forth in claim 16 wherein the magnetic resonance exciting and manipulating includes applying an echo-planar imaging sequence.

Claim 27

The method as set forth in claim 19 wherein the echo-planar imaging sequence is applied with a repeat time and a resolution such that two-dimensional images of at least six slices are generated per second, whereby substantially real time imaging is provided.

Claim 28

The method as set forth in claim 15 wherein a single one-dimensional projection image of each slice is obtained, the one-dimensional projection images of a multiplicity of slices taken together being a two-dimensional shadowgraphic, projection image.

Claim 31

The method as set forth in claim 22 further including: monitoring a cardiac cycle of the subject; coordinating moving of the subject and incrementing of the frequency of the excited resonance and the demodulation frequency with the monitored cardiac cycle.