Koninklijke Philips Corporation N.v.

Cornelis Leonardus Gerardus Ham

Paul Royston Harvey

Nicolaas Bernardus Roozen

Marinus Johannes Adrianus Maria Van Helvoort

Patrick Willem Paul Limpens

Johan Samuel Van Den Brink

Filips Van Liere

Johannes Petrus Groen

Gerardus Bernardus Jozef Mulder

Robert Paul Kleihorst

Martijn Roger La Grange

Xianrui Huang

Miha Fuderer

Marc Paul Saes

Johannes Adrianus Overweg

Yan Zhao

Jan Konijn

Jian Lin

Paulus Cornelius Hendrikus Adrianus Haans

Yun Zhou

Wilhelmus Reinerius Maria Mens

Martin Alexander Hollander

Johannes Den Boef

Lambertus De Vries

Martijn Krelis Termeer

Jun Pan

Hans H Tuithof

Marinus Ludovicus Adrianus Vrinten

Diana Maria Francisca Geraats

Michael Paul Bax

Marcellus Hendricus Marinus Waltherus Melters

The present invention provides a method for compensation of periodic Bmodulations from a periodic motion of a cold head () of a main magnet () of a magnetic resonance (MR) imaging system (), whereby main windings () of the main magnet () are cooled to superconductivity by the cold head (), which exerts a repetitive motion, the method comprising the steps of measuring a periodic occurrence of spatial field components of the B-field based on a motion of the cold head () as a function of time, performing a sensor measurement of a periodic, auxiliary parameter of the MR imaging system (), which is not the periodic occurrence of spatial field components, synchronizing the periodic occurrence of spatial field components of the B-field with the measured periodic, auxiliary parameter of the MR imaging system (), and triggering based on the measured periodic sensor measurement of the MR imaging system () a periodic application of compensation signals to compensate the periodic occurrence of spatial field components of the B-field based on a motion of the cold head (). Furthermore, the present invention provides a MR imaging system () for providing an image representation of a region of interest () of a subject of interest () positioned in an examination space () of the MR imaging system (), wherein the MR imaging system () is adapted to perform the above method.

Compensation of magnetic field components caused by a periodic motion of a cold head

A magnetic resonance imaging (MRI) system includes a superconducting magnet assembly with a superconducting field coil for generating a stationary uniform main magnetic field. A gradient system includes a gradient coil for generating gradient magnetic fields and a gradient amplifier which is connectable to the gradient coil for driving the gradient coil. A switch assembly is adapted for galvanically coupling the superconducting field coil to the gradient amplifier. In this way, it is possible for energizing and discharging a superconducting magnet of an MRI system in an easy and cost-efficient way.

Energizing and discharging a superconducting magnet of an MRI system

In a magnetic resonance examination system, the patient carrier is mounted moveably in a direction transverse to the support surface and an RF antenna has a fixed geometrical relation to the support surface.

Magnetic resonance examination system with a moveable patient carrier

A gradient coil assembly () for use in a Magnetic Resonance Imaging (MRI) system includes primary coils (), shield coils () and a supporting structure () arranged between the primary coils () and the shield coils (). The supporting structure () includes at least a supporting element () including a first end face () and at least a first recess () with an opening () in the first end face (). The first recess () extends in a longitudinal direction () of the supporting element () forming a tray for receiving a passive shim bar.

Supporting structure for a gradient coil assembly of a MRI

A superconducting magnet includes superconducting magnet coils (C, C, C, C, C, C, S, S) disposed inside a magnet cryostat (). The superconducting magnet coils generate a static (B) magnetic field when an electric current flows in the superconducting magnet coils. A superconducting Bcompensation circuit () is also disposed inside the magnet cryostat, and is coupled with the superconducting magnet coils to passively reduce temporal variations in the Bmagnetic field generated by the superconducting magnet coils. An electric current sensor () is also disposed inside the magnet cryostat and is connected to measure electric current flowing in the superconducting Bcompensation circuit. An active Bcompensation component () is operatively connected with the electric current sensor to receive the measurement of electric current flowing in the superconducting Bcompensation circuit and to provide active Bmagnetic field compensation based on the measured electric current.

Cryogenic field sensing for compensating magnetic field variations in magnetic resonance imaging magnets

A magnetic resonance (MR) imaging apparatus comprises an MR imaging device () including a magnet () and heat generating components (). A cooling system () cools the heat generating components using chilled water from an air-cool chiller (). Sensors (TS, VS) are configured to measure thermal parameters of the heat generating components or of the cooling system. An MR controller () controls the MR imaging device to execute an MR imaging examination program ('exam card') () and to adjust the execution of the MR imaging examination program in response to a thermal parameter measured by the one or more sensors indicating the cooling system has insufficient cooling capacity. The MR controller may also adjust the exam card prior to its execution if the cooling system () has insufficient cooling capacity at the current air temperature to dissipate the heat load as estimated by a power dissipation model ().

Magnetic resonance imaging with improved thermal performance

A magnetic resonance examination system comprises cooling clients () from which heat is carried-off by way of a system cooling circuit. A heat source () is in thermal contact with the system cooling circuit. A main pump () drives flow of the coolant in the system cooling circuit. The coolant is kept in motion and may be heated by the heat source. Thus, freezing of the coolant is avoided without the need of antifreeze. A back-up pump () of lower performance requirements may maintain flow of the coolant even if the main pump fails. A low viscosity coolant, such as water may be used. The system also contains a shut-off valve () and a short-circuit () parallel to the shut-off valve.

Magnetic resonance examination system with fluid cooling arrangement

The invention provides for a magnetic resonance imaging system () comprising: a magnet () for generating a main magnetic field with a homogeneous field zone (); an antenna () with an imaging zone () that has a fixed geometric relationship with portion () of a subject (); a radio frequency system () for generating a radio frequency pulse (); a magnetic gradient field system (); and a patient support () for automatically moving the antenna and the portion of the subject from outside of the homogeneous field zone to within the homogeneous field zone along a movement axis. Machine executable instructions () cause a processor () controlling the magnetic resonance imaging system to: move the antenna and the portion from outside of the homogeneous field zone to within the homogeneous field zone along the movement axis; control () the radio frequency system to repeatedly generate a radio frequency pulse; control () the magnetic gradient field system to generate a gradient magnetic field during movement of the subject support only along the movement axis; control () the radio frequency system to repeatedly measure the radio frequency signal from the portion of the subject using the antenna; determine () a current location () of the antenna or of the imaging zone using the radio frequency signal; and control () the patient support to decelerate and halt at a predetermined location () within the homogeneous field zone using the current location.

Positioning of a magnetic resonance imaging antenna within the homogeneous field zone

The present invention provides acryogenic vessel (), in particular for use in a magnetic resonance examination system () to mount therein superconductive main coils () of the magnetic resonance examination system (), comprising an inner vessel (), an outer 300K vessel (), and a radiation shield (), which is located between the inner vessel () and the outer 300K vessel () and which surrounds the inner vessel (), whereby the radiation shield () has at least one dry-friction area (), where dry-friction is generated upon deformation of the radiation shield (). The present invention also provides a superconductive magnet () for a magnet resonance examination system () comprising a set of superconductive main coils (), which are arranged in the above cryogenic vessel (). The present invention further provides a magnet resonance examination system () comprising the above superconductive magnet ().

Dynamic boil-off reduction with improved cryogenic vessel

The present invention provides a gradient coil assembly () for use in a magnetic resonance imaging system () comprising a set of inner coils () and a set of outer coils (), which are concentrically arranged in respect to a common rotational axis of the set of inner and outer coils (), wherein the set of inner coils () and a set of outer coils () can be controlled to generate gradient magnetic fields within an inner space of the gradient coil assembly (), and at least one coil () of the set of outer coils () is at least partially made of aluminum. The present invention further provides a magnetic resonance (MR) imaging system () comprising the above magnetic gradient coil assembly (). By replacing at least a part of one coil of the outer coils by aluminum, the gradient coil assembly () can be significantly improved in respect to cost and weight without reducing the accuracy in respect to the generation of diagnostic images based on magnetic resonance information. Accordingly, the outcome of an MR scan is not reduced. The outer coils usually contain about half the weight of the copper used for state of the art gradient coil assemblies.

Gradient coil assembly with outer coils comprising aluminum

The present invention relates to a method for supplying current to a gradient coil () of a magnetic resonance imaging system () by a gradient amplifier (), the method comprising: supplying, by an electrical power supply (), a voltage at first level to the gradient amplifier output to generate a gradient current in the gradient coil () to produce a magnetic gradient field at an slew rate, wherein the slew rate is set to a first value, resetting the slew rate to a second value, comparing the second value to the first value, and adjusting the voltage to a second level if the second value is different from the first value.

MRI gradient amplifier operable at different slew rates

A power supply unit () powers at least one gradient coil () of a magnetic resonance (MR) examination system () with a main magnet () having, in at least one state of operation, a substantially static magnetic field strength, and with an MR measurement signal bandwidth. The power supply unit () includes a switched-mode power converter () for powering the at least one gradient coil (), and including at least one switching member provided to switch between a conducting state configuration and an essentially non-conducting state configuration at a first fundamental switching frequency (fSW). A pulse control unit () is designed to provide switching pulses at the first fundamental switching frequency (fSW) for controlling the switching of the at least one switching member. Upon triggering by a trigger signal (), the pulse control unit () is provided to change the first fundamental switching frequency (fSW) to at least a second fundamental switching frequency (fSW).

Switching-frequency-controlled switch-mode power supply unit for powering magnetic resonance system gradient coils

A magnetic resonance apparatus corrects higher order Bmagnetic field inhomogeneities in the examination volume of an MR device. Currents through two or more coil sections (X, X) of at least one of a plurality of gradient coils () are independently controlled in such a manner that higher order field inhomogeneities of the main magnetic field Bare compensated for by the magnetic field of the at least one gradient coil ().

[object Object]

The invention relates to a magnetic resonance imaging system () comprising: a main magnet () for generating a uniform, steady magnetic field within an examination volume, at least one RF antenna () for transmitting RF pulses to the examination volume for magnetic resonance spin excitation, a gradient coil unit comprising gradient coils () for generating gradient magnetic fields in the examination volume (), an RF shield () disposed between said RF antenna () and said gradient coils (), said RF shield () comprising a shielding material adapted for suppressing Eddy currents induced in the shield by said gradient magnetic fields and for screening RF fields towards the gradient coils (), said RF fields being generated by the RF antenna (), wherein the RF shield comprises a conductive coating () as shielding material.

RF shield for MRI comprising conductive coating as shielding material

A gradient coil power supply includes: at least two H-bridge circuits connected in series, wherein each H-bridge circuit supplies: voltage of a first polarity when in a first switching state, voltage of a second polarity when in a second switching state, no voltage when in a third switching state, and no voltage when in a fourth switching state; and a controller for controlling the switching of the H-bridge circuits. The controller is adapted for: receiving a gradient pulse sequence; creating a switching plan for controlling the switching of the H-bridge circuits, wherein the switching plan includes controlling the voltage output of the gradient coil power supply by alternating between the first switching state and the second switching state, and at least one H-bridge circuit being in either the third or fourth switching state for part of the switching plan to cool the H-bridge circuit; and executing the switching plan.

Growing community of inventors

Eindhoven, Netherlands

Cornelis Leonardus Gerardus Ham