Magnetic Resonance Imaging System, a Method of Magnetic Resonance Imaging and a Computer Program

• US 20070216410A1
• Filed: 04/27/2005
• Published: 09/20/2007
• Est. Priority Date: 04/29/2004
• Status: Active Grant

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Thelissen, Guillaume, Bos, Clemens
• Granted Patent: US 7,508,205 B2
• Time in Patent Office: Days
• US Class Current: 324/315
• CPC Class Codes: G01R 33/4804 Spatially selective measurement of temperature or pH

Abstract

The magnetic resonance imaging system 1 according to the invention comprises a data acquisition system 11 with a main magnet 12 with an imaging volume (not shown) therein. Gradient system (G) arranged for generating field gradients Gx indicated as 14, Gy indicated as 16 and Gz indicated as 17 is provided. An RF excitation system (10) is provided for generating radio-frequency (RF) pulses for flipping aligned spins into a transverse plane such as the XY plane or to have a component in the XY plane. The system (10) for flipping the spins comprises RF coils (not shown) in the magnet 12 and a pulse transmitter 18. The pulse transmitter frequency may be supplied by a synthesizer 19 and can be controlled by a control system 21. The control system 21 is arranged to control the time and amplitude of the outputs of the various component parts making up the magnetic resonance apparatus. The transmitted pulse is supplied from the transmitter 18 through a transmitter-receiver selection switch 22 to an RF coil (not shown) in the magnet. The systhesizer signal is coupled to the transmitter 18 when the system is in the transmitting mode through a second transmitter-receiver switch 23. In the receiving mode, the RF coil in the magnet senses a response of the investigated object to the RF pulses, for example in the form of a free induction decay signals, including echo signals. The signals received at the RF coil are supplied through switch 22 when it is switched by the control system 21 into the receiving mode to connect the RF coil to the receiver The receiver signal then passes through an analog-to-digital converter 25. The digital output of the converter 25 is applied to an image reconstructor 26, preferably having an associated memory 27. The image reconstructor 26 is arranged to extract thermometry data and longitudinal relaxation time data from the acquired MR signals and to forward corresponding reconstructed images to the display unit 28. The invention further relates to a method of magnetic resonance imaging and a computer program.

Claims

1. A magnetic resonance imaging system (1) comprising

a data acquisition system with a

a main magnet for generating a magnetic field in an imaging volume,

a gradient system for generating a gradient in said magnetic field;

an RFE excitation system arranged for generating a radio-frequency wave in the imaging volume, said radio-frequency wave being conceived to interact with a matter to be positioned in the imaging volume;

an acquisition means arranged to detect a signal representative of a response of the matter to said radio-frequency wave,

said magnetic resonance imaging system further comprising

a control system 94+arranged to operate the data acquisition system for generating a dataset comprising a plurality of signals,

a reconstructor operable to reconstruct an image based on said dataset, and said control system being further arranged to form said dataset to comprise a signal phase data and a signal magnitude data, said reconstruction means being arranged to reconstruct an image representative of a local thermometry data and a local longitudinal relaxation data using said phase data and said magnitude data.

2. A magnetic resonance imaging system according to claim 1, wherein said system further comprises a heating device arranged to locally elevate a temperature in the matter, said magnetic resonance imaging system being further arranged to monitor the local thermometry data in the matter and to control the heating device in accordance with a pre-set control program.

3. A magnetic resonance imaging system according to claim 2, wherein said control program comprises a set of instructions for controlling a heating mode.

4. A magnetic resonance imaging system according to claim 2, wherein said heating device is arranged to elevate the local temperature within the matter in a spot, said control program comprising a further set of instructions for controlling a position of said spot.

5. A magnetic resonance imaging system according to claim 1, wherein said system is further arranged to monitor a change in the signal magnitude data and to generate a further signal representative of said change.

6. A magnetic resonance imaging system according to claim 5, wherein a contrast agent encapsulated in a thermo-sensitive shield is introduced into the matter, the farther signal being generated upon an event of a detection of the contrast agent outside the shield.

7. A magnetic resonance imaging system according to claim 5, wherein said contrast agent is associated with a pharmaceutical to be transported to a target within the matter, a transport of the pharmaceutical being monitored by said imaging system based on said signal magnitude data.

8. A method of magnetic resonance imaging comprising the steps of:

positioning a matter to be investigated in an imaging volume of a magnetic resonance apparatus;

acquiring a dataset using the magnetic resonance apparatus, said dataset being representative of a temperature data of the matter and a longitudinal relaxation data of the matter;

reconstructing an image representative of said temperature data and said longitudinal relaxation data.

9. A method according to claim 8, said method further comprising the steps of:

selecting for the matter an object comprising a contrast agent encapsulated in a thermosensitive shield, said shield being conceived to increase its permeability to the contrast agent and/or to surrounding water upon an event a threshold temperature is reached;

heating the matter using a heating device at least until the threshold temperature is reached;

detecting an event the contrast agent leaving the shield.

10. A method according to claim 9, wherein the method further comprises the step of controlling the heating device in accordance with the temperature data and/or the longitudinal relaxation data.

11. A computer program containing instructions for a reconstruction of an image comprising a local temperature data and a local longitudinal relaxation data from a sole dataset of magnetic resonance signals.

12. A computer program according to claim 11, wherein said computer program is further arranged to contain further instructions for monitoring the local temperature data and/or the local longitudinal relaxation data.

13. A computer program according to claim 12, wherein said computer program further comprises instructions to control a device in accordance with a reading of the local temperature data and/or the local longitudinal relaxation data.