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

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.

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.

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.

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.

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.

A method of magnetic resonance imaging comprising:

• creating a uniform, temporally constant magnetic field in a thin imaging volume which has 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;
• moving a subject continuously through the thin imaging volume transverse to the imaging region height and width;
• while the subject is moving through the thin imaging volume, exciting and manipulating magnetic resonance in a selected slice of the subject that is in the imaging region and receiving magnetic resonance signals from the selected slice;
• reconstructing the magnetic resonance signals from a plurality of slices into an image representation.

A method of magnetic resonance imaging comprising:

• creating a temporally constant magnetic field in an imaging region which is at least twice a slice thickness and less than 15 cm thick;
• moving a subject continuously through the thin imaging volume;
• while the subject is moving through the thin imaging volume, exciting and manipulating magnetic resonance in a selected slice of the subject that is in the imaging volume and receiving magnetic resonance signals from the selected slice, the step of exciting and manipulating magnetic resonance and receiving magnetic resonance signals from the selected slice including:
• applying a slice select gradient along a direction of subject movement, and
• incrementing a frequency of the excited resonance and a demodulation frequency of the received resonance signals to shift the selected slice;
• reconstruction the magnetic resonance signals from a plurality of slices into an image representation.

A method of magnetic resonance imaging comprising:

• creating a uniform, temporally constant magnetic field in an imaging volume which is at least twice a slice thickness and less than 10 cm thick;
• moving a subject continuously through the thin imaging volume;
• while the subject is moving through the thin imaging volume, exciting and manipulating magnetic resonance in a selected slice of the subject that is in the imaging region, the magnetic resonance exciting and manipulating including:
• applying a slice select gradient along a direction of subject movement,
• applying phase encode gradients which are changed in each repetition such that the received magnetic resonance signals have a range of phase encoding from a central phase encoding to positive and negative high frequency phase encodings on opposite sides of the central phase encoding,
• applying the positive and negative high frequency phase encoding gradients in temporally contiguously repetitions and applying the central phase encoding gradient in less temporally contiguous repetitions;
• receiving magnetic resonance signals from the selected slice;
• 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 of magnetic resonance and the receiving magnetic resonance signals;
• reconstructing the magnetic resonance signals from a plurality of slices into an image representation.

A method of magnetic resonance imaging comprising:

• creating a uniform, temporally constant magnetic field in an imaging region which is at least twice a slice thickness and less than 15 cm thick;
• moving a subject continuously through the thin imaging region,
• while the subject is moving through the thin imaging region, exciting and manipulating magnetic resonance in a selected slice of the subject that is in the imaging region including:
• applying a slice select gradient along a direction of subject movement,
• shifting the selected slice relative to the imaging region such that the selected slice remains fixed relative to the subject,
• applying a flow imaging magnetic resonance sequence such that the reconstructed image representation represents flow velocities;
• receiving magnetic resonance signals from the selected slice;
• reconstructing the magnetic resonance signals from a plurality of slices into an image representation.