ACOUSTIC RADIATION FORCE MAGNETIC RESONANCE IMAGING

• US 20150190659A1
• Filed: 06/28/2013
• Published: 07/09/2015
• Est. Priority Date: 07/09/2012
• Status: Active Grant

• Current Assignee: Profound Medical Inc. (Profound Medical Corp.)
• Original Assignee: Koninklijke Philips N.V.
• Inventors: Khler, Max Oskar
• Granted Patent: US 10,406,384 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: A61B 2018/00791 Temperature
• CPC Class Codes: A61B 2090/374 NMR or MRI
• CPC Class Codes: A61B 2505/05 Surgical care
• CPC Class Codes: A61B 5/015 By temperature mapping of body part
• CPC Class Codes: A61B 5/055 involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
• CPC Class Codes: A61B 5/7278 Artificial waveform generation or derivation, e.g. synthesising signals from measured signals A61B5/327 takes precedence
• CPC Class Codes: A61B 5/748 Selection of a region of interest, e.g. using a graphics tablet
• CPC Class Codes: A61N 2007/0039 using microbubbles
• CPC Class Codes: A61N 7/02 Localised ultrasound hyperthermia hyperthermia in general A61F7/00
• CPC Class Codes: G01R 33/4814 MR combined with ultrasound
• CPC Class Codes: G01R 33/4833 using spatially selective excitation of the volume of interest, e.g. selecting non-orthogonal or inclined slices
• CPC Class Codes: G01R 33/543 Control of the operation of the MR system, e.g. setting of acquisition parameters prior to or during MR data acquisition, dynamic shimming, use of one or more scout images for scan plane prescription G01R33/546 takes precedence
• CPC Class Codes: G01R 33/5611 Parallel magnetic resonance imaging, e.g. sensitivity encoding [SENSE], simultaneous acquisition of spatial harmonics [SMASH], unaliasing by Fourier encoding of the overlaps using the temporal dimension [UNFOLD], k-t-broad-use linear acquisition speed-up technique [k-t-BLAST], k-t-SENSE structural details of arrays of sub-coils G01R33/3415
• CPC Class Codes: G01R 33/5612 Parallel RF transmission, i.e. RF pulse transmission using a plurality of independent transmission channels

Abstract

The invention provides for medical instrument (200, 400) comprising a magnetic resonance imaging system (202) and a high intensity focused ultrasound system (222). A processor (246) controls the medical instrument. Instructions cause the processor to control (100) the magnetic resonance imaging system to acquire the magnetic resonance data using a pulse sequence (254). The pulse sequence comprises an acoustic radiation force imaging pulse sequence (500, 600). The acoustic radiation force imaging pulse sequence comprises an excitation pulse (512) and a multi-dimensional gradient pulse (514) applied during the radio frequency excitation pulse for selectively exciting a region of interest (239) encompassing a target zone and at least a portion of the beam axis. The instructions cause the processor to control (102) the high intensity focused ultrasound system to sonicate the target zone during the acoustic radiation force imaging pulse sequence and reconstruct (104) a radiation force image (258) using the magnetic resonance data.

Claims

1. A medical instrument comprising:

a magnetic resonance imaging system for acquiring magnetic resonance data from a subject within an imaging zone;

a high intensity focused ultrasound system for directing ultrasound along a beam axis for sonicating a target zone, wherein the target zone is within the imaging zone;

a processor for controlling the medical instrument;

a memory for storing machine readable instructions, wherein execution of the instructions causes the processor to;

control the magnetic resonance imaging system to acquire the magnetic resonance data using a pulse sequence, wherein the pulse sequence comprises an acoustic radiation force imaging pulse sequence, wherein the acoustic radiation force imaging pulse sequence comprises an excitation pulse, wherein the acoustic radiation force imaging pulse sequence comprises a multi-dimensional gradient pulse applied during the radio frequency excitation pulse for selectively exciting a region of interest, the multi-dimensional gradient pulse being a two-dimensional gradient pulse for exciting the region of interest such that the region of interest has a two dimensional cross section, wherein the two-dimensional cross section has rotational symmetry with respect to a region of interest axis, and wherein the region of interest axis and the beam axis are coaxial and

wherein the region of interest comprises a predetermined volume that encompasses the target zone and at least a portion of the beam axis; and

control the high intensity focused ultrasound system to sonicate the target zone such that the sonication of the target zone occurs during the acoustic radiation force imaging pulse sequence; and

reconstruct a radiation force image using the magnetic resonance data.

3. The medical instrument of claim 1, wherein the two-dimensional excited volume has any one of the following:

a circular cross-section, an elliptical cross section, a rectangular cross-section, and a polygonal cross-section.

4. The medical instrument of claim 3, wherein the imaging pulse sequence further comprises a one-dimensional readout gradient pulse aligned with the beam axis.

6. The medical instrument of claim 1, wherein the pulse sequence is any one of the following:

a SENSE pulse sequence or a GRAPPA pulse sequence.

7. The medical instrument of claim 1 wherein the motion encoding gradient is a bi-polar gradient pulse.

8. The medical instrument of claim 1, wherein execution of the instructions causes the processor to perform any one of the following using the radiation force image:

detect bubbles, detect tissue necrosis, determine tissue displacement, adjust target position, drive signal optimization for the high intensity focused ultrasound system, and combinations thereof.

9. The medical instrument of claim 1, wherein the excitation pulse is a single excitation pulse.

10. The medical instrument of claim 1, wherein the pulse sequence further comprises a displacement encoding gradient pulse, wherein execution of the instructions cause the processor to control the high intensity focused ultrasound system to sonicate the target zone using the high intensity focused ultrasound system such that the sonication of the target zone occurs during at least a portion of the displacement encoding gradient pulse.

11. The medical instrument of claim 1, wherein the pulse sequence further comprises an outer volume suppression pulse sequence for attenuating magnetic resonance signal outside of the region of interest.

12. The medical instrument of claim 1, wherein the pulse sequence comprises a thermal imaging pulse sequence for acquiring thermal magnetic resonance data, wherein the thermal imaging pulse sequence is interleaved with the acoustic radiation force imaging pulse sequence, wherein execution of the instructions further causes the processor to:

control the magnetic resonance imaging system to acquire the thermal magnetic resonance data using the thermal imaging pulse sequence;

reconstruct a thermal map using the thermal magnetic resonance data; and

display the thermal map and the radiation force image on a display.

13. The medical instrument of claim 1, where the high intensity focused ultrasound system has an adjustable focus for controlling the location of the target zone, wherein execution of the instructions further causes the processor to:

receive a treatment plan specifying a location of the target zone within the subject;

control the high intensity focused ultrasound system to repeatedly control the adjustable focus at least partially in accordance with the radiation force image and the treatment plan in real time.

2. (canceled)

5. The medical instrument of claim 2, wherein the magnetic resonance imaging system comprises a multi-element transmit coil, wherein the pulse sequence is operable for causing the magnetic resonance imaging system to restrict the region of interest to the predetermined volume using the multi-element transmit coil using the multi-dimensional excitation.

14. A computer program product comprising machine executable code for execution by a processor controlling a medical instrument, wherein the medical instrument comprises a magnetic resonance imaging system for acquiring magnetic resonance data from a subject within an imaging zone, wherein the medical instrument further comprises a high intensity focused ultrasound system for directing ultrasound along a beam axis for sonicating a target zone, wherein the target zone is within the imaging zone, wherein execution of the instructions causes the processor to:

control the magnetic resonance imaging system to acquire the magnetic resonance data using a pulse sequence, wherein the pulse sequence comprises an acoustic radiation force imaging pulse sequence, wherein the acoustic radiation force imaging pulse sequence comprises an excitation pulse, wherein the acoustic radiation force imaging pulse sequence comprises a multi-dimensional gradient pulse applied during the radio frequency excitation pulse for selectively exciting a region of interest, the multi-dimensional gradient pulse being a two-dimensional gradient pulse for exciting the region of interest such that the region of interest has a two dimensional cross section, wherein the two-dimensional cross section has rotational symmetry with respect to a region of interest axis, and wherein the region of interest axis and the beam axis are coaxial and

wherein the region of interest comprises a predetermined volume that encompasses the target zone and at least a portion of the beam axis; and

control the high intensity focused ultrasound system to sonicate the target zone such that the sonication of the target zone occurs during the acoustic radiation force imaging pulse sequence; and

reconstruct a radiation force image using the magnetic resonance data.

15. A method of operating a medical instrument, wherein the medical instrument comprises a magnetic resonance imaging system for acquiring magnetic resonance data from a subject within an imaging zone, wherein the medical instrument further comprises a high intensity focused ultrasound system for directing ultrasound along a beam axis for sonicating a target zone, wherein the target zone is within the imaging zone, wherein the method comprises the steps of:

controlling the magnetic resonance imaging system to acquire the magnetic resonance data using a pulse sequence, wherein the pulse sequence comprises an acoustic radiation force imaging pulse sequence, wherein the acoustic radiation force imaging pulse sequence comprises an excitation pulse, wherein the acoustic radiation force imaging pulse sequence comprises a multi-dimensional gradient pulse applied during the radio frequency excitation pulse for selectively exciting a region of interest, the multi-dimensional gradient pulse being a two-dimensional gradient pulse for exciting the region of interest such that the region of interest has a two dimensional cross section, wherein the two-dimensional cross section has rotational symmetry with respect to a region of interest axis, and wherein the region of interest axis and the beam axis are coaxial and

wherein the region of interest comprises a predetermined volume that encompasses the target zone and at least a portion of the beam axis; and

controlling the high intensity focused ultrasound system to sonicate the target zone such that the sonication of the target zone occurs during the acoustic radiation force imaging pulse sequence; and

reconstructing a radiation force image using the magnetic resonance data.