Temperature measurement near an ice ball using a proton resonance frequency method and recalculation of susceptibility artifacts

• US 8,706,190 B2
• Filed: 11/10/2010
• Issued: 04/22/2014
• Est. Priority Date: 11/10/2010
• Status: Expired due to Fees

• Current Assignee: Siemens Healthcare GMBH (Siemens AG)
• Original Assignee: Siemens AG
• Inventors: Gross, Patrick, Kickhefel, Antje, Roland, Joerg, Salomir, Rares
• Primary Examiner(s): KISH, JAMES M
• Application Number:
  US12/943,381
• Publication Number:
  US 20120116208A1
• Time in Patent Office: 1,259 Days
• Field of Search: 600/407, 600410-423, 324300-322
• US Class Current: 600/412
• CPC Class Codes: G01R 33/4804 Spatially selective measurement of temperature or pH
• CPC Class Codes: G01R 33/56536 due to magnetic susceptibility variations

Abstract

In a method or system for magnetic resonance imaging based temperature monitoring for real-time feedback to a physician for a cryoablation therapy of a lesion which creates an ice ball of the lesion to induce cell death, the magnetic resonance imaging system, using proton resonance frequency imaging, obtains a real-time temperature image of the ice ball of the lesion undergoing the cryoablation therapy and the adjacent surrounding tissue. By use of an algorithm, correcting temperature errors at a border of the ice ball are corrected in the real-time image, the temperature error correction correcting susceptibility contrast errors caused by a distortion of the local magnetic field at the border of the ice ball.

Claims

1. A method for magnetic resonance imaging based temperature monitoring for real-time feedback to a physician for a cryoablation therapy of a lesion which creates an ice ball of the lesion to induce cell death, a border of the ice ball having a water physical state, comprising the steps of:

with a magnetic resonance imaging system, performing proton resonance frequency (PRF) imaging and obtaining a real-time gradient echo sequence (GRE) phase temperature image of the ice ball of the lesion undergoing the cryoablation therapy and surrounding tissue adjacent the lesion;

applying an algorithm to said real-time gradient echo sequence phase temperature image that corrects temperature errors at said border of the ice ball, said temperature error correction correcting susceptibility contrast errors caused by a distortion of a local magnetic field resulting from differences in susceptibility between frozen tissue and non-frozen tissue, said algorithm accounting for the susceptibility differences by simulating susceptibility artifacts, wherein said susceptibility differences are determined by searching for a minimum of a cost function defined as a standard deviation at a corrected temperature series, the border of the ice ball being assumed to have a water physical state transition temperature so that the algorithm corrects phase data for the gradient echo sequence phase temperature image for said susceptibility artifacts; and

said algorithm comprising the following

2. The method of claim 1 wherein said algorithm comprises a convolution of a k-space and a perturbation field defined by the susceptibility differences.

3. The method of claim 1 wherein said temperature monitoring comprises non-invasive monitoring of near zero temperatures at tissues adjacent to the lesion.

4. The method of claim 1 wherein said lesion comprises a tumor.

5. The method of claim 1 wherein said algorithm comprises a convolution in k-space that has a susceptibility contrast matrix.

6. A system for magnetic resonance imaging based temperature monitoring for real-time feedback to a physician for a cyroablation therapy of a lesion which creates an ice ball of the lesion to induce cell death, a border of the ice ball having a water physical state, comprising:

a magnetic resonance imaging system configured to perform proton resonance frequency imaging to obtain a real-time gradient echo sequence (GRE) temperature image of the ice ball of the lesion undergoing the cryoablation therapy and adjacent surrounding tissue the lesion;

said magnetic resonance imaging system configured to use an algorithm to correct temperature errors at said border of the ice ball in the real-time image, said temperature error correction correcting for susceptibility contrast errors caused by a distortion of a local magnetic field resulting from differences in susceptibility between frozen tissue and non-frozen tissue, said algorithm accounting for the susceptibility differences by simulating susceptibility artifacts, said susceptibility differences being determined by searching for a minimum of a cost function defined as a standard deviation at a corrected temperature series, said border of the ice ball being assumed to have a water physical state transition temperature so that the algorithm corrects phase data for the gradient echo sequence temperature image for said susceptibility artifacts; and

said algorithm comprising the following