ESTIMATION OF ALIGNMENT PARAMETERS IN MAGNETIC-RESONANCE-GUIDED ULTRASOUND FOCUSING

• US 20110034800A1
• Filed: 08/04/2009
• Published: 02/10/2011
• Est. Priority Date: 08/04/2009
• Status: Active Grant

• Current Assignee: InSightec Ltd.
• Original Assignee: InSightec Ltd.
• Inventors: Seginer, Amir, Vitek, Shuki, Schmidt, Rita
• Granted Patent: US 9,623,266 B2
• Time in Patent Office: Days
• US Class Current: 600/411
• CPC Class Codes: A61B 2017/00725 Calibration or performance testing
• CPC Class Codes: A61B 2090/374 NMR or MRI
• CPC Class Codes: A61B 2090/3954 magnetic, e.g. NMR or MRI
• CPC Class Codes: A61B 5/055 involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
• CPC Class Codes: A61B 8/587 Calibration phantoms models for medical purposes G09B23/28
• CPC Class Codes: A61N 2007/0065 Concave transducers
• CPC Class Codes: A61N 2007/0078 with multiple treatment transducers
• CPC Class Codes: A61N 2007/0095 by modifying an excitation signal
• CPC Class Codes: A61N 7/02 Localised ultrasound hyperthermia hyperthermia in general A61F7/00
• CPC Class Codes: G01R 33/4814 MR combined with ultrasound

Abstract

A magnetic-resonance-guided focused ultrasound system may be calibrated by generating ultrasound foci using ultrasound transducers, establishing coordinates of the foci and of magnetic-resonance trackers associated with the transducers, and determining a geometric relationship between the trackers and the transducers.

Claims

1. A method for calibrating a magnetic-resonance-guided focused-ultrasound system, comprising:

(a) providing a phased array of ultrasound transducers, the array having at least one magnetic resonance (MR) tracker associated therewith at a fixed relative position with respect thereto;

(b) establishing MR coordinates of the MR trackers;

(c) for each of a plurality of sonication schemes, (i) creating an ultrasound focus, and (ii) establishing parameters indicative of MR coordinates of the ultrasound focus; and

,

(d) based at least in part on the parameters, determining a geometric relationship between the ultrasound transducers and the MR trackers.

2. The method of claim 1 wherein the MR trackers and the array are part of a single rigid structure.

3. The method of claim 1 wherein the MR trackers comprise at least one of a micro-coil or an MR imaging marker.

4. The method of claim 1 wherein the ultrasound focus is created in a phantom.

5. The method of claim 1 wherein establishing the MR coordinates of the ultrasound focus comprises at least one of thermal MR imaging or acoustic-radiation-force MR imaging.

6. The method of claim 1 wherein the parameters comprise the MR coordinates of the ultrasound focus.

7. The method of claim 1 wherein the parameters comprise MR coordinates of a projection of the ultrasound focus.

8. The method of claim 1 wherein the determination of the geometric relationship is further based on the sonication schemes.

9. The method of claim 1 wherein the geometric relationship comprises coordinates of the MR trackers in a transducer coordinate system.

10. The method of claim 9 wherein determining the geometric relationship comprises determining a transformation between the MR coordinate system and the transducer coordinate system based, at least in part, on the parameters and the sonication schemes.

11. The method of claim 10 wherein determining the geometric relationship further comprises using the transformation to determine the coordinates of the MR trackers in the transducer coordinate system.

12. The method of claim 1 wherein the geometric relationship comprises production errors indicative of a deviation of the fixed relative positions between the MR trackers and the transducers from nominal relative positions.

13. The method of claim 12 wherein determining the geometric relationship comprises determining a transformation between the parameters and the production errors based, at least in part, on the sonication scheme.

14. The method of claim 13 wherein determining the geometric relationship further comprises applying a linear estimation method to the transformation and the parameters, thereby determining the production errors.

15. The method of claim 14 wherein the linear estimation method comprises a least square method.

16. A method for operating a magnetic-resonance-guided focused-ultrasound system, comprising:

(a) providing a phased array of ultrasound transducers, the array having at least one magnetic resonance (MR) tracker associated therewith at a fixed relative position with respect thereto;

(b) establishing MR coordinates of the MR trackers;

(c) for each of a plurality of sonication schemes, (i) creating an ultrasound focus, and (ii) establishing parameters indicative of MR coordinates of the ultrasound focus;

(d) based at least in part on the parameters, determining a geometric relationship between the ultrasound transducers and the MR trackers; and

(e) operating the magnetic-resonance-guided focused-ultrasound system by focusing ultrasound into a target region having MR coordinates, based on the geometric relationship.

17. A system for calibrating a magnetic-resonance-guided ultrasound-focusing system comprising:

(a) a phased array of ultrasound transducers, the array having at least one magnetic resonance (MR) tracker associated therewith at a fixed relative position with respect thereto;

(b) an MR imaging apparatus; and

(c) a control facility for (i) driving the phased array according to a sonication scheme so as to generate an ultrasound focus, (ii) receiving MR imaging data indicative of MR coordinates of the ultrasound focus and the MR trackers, and (iii) determining a geometric relationship between the ultrasound transducers and the MR trackers based, at least in part, on the MR imaging data.

18. The system of claim 17 further comprising a phantom in which the ultrasound focus is generated.

19. A magnetic-resonance-guided ultrasound-focusing system comprising:

(a) a phased array of ultrasound transducers, the array having at least one magnetic resonance (MR) tracker associated therewith at a fixed relative position with respect thereto;

(b) an MR imaging apparatus;

(c) a user interface facilitating selection of a target region in MR coordinates; and

(d) a control facility for (i) driving the phased array according to a sonication scheme so as to generate an ultrasound focus, (ii) receiving MR imaging data indicative of MR coordinates of the ultrasound focus and the MR trackers, (iii) determining a geometric relationship between the ultrasound transducers and the MR trackers based, at least in part, on the MR imaging data, and (iv) operating the magnetic-resonance-guided focused-ultrasound system by focusing ultrasound into the target region based on the geometric relationship.