Dielectric element and method for generating a magnetic resonance image therewith

• US 20050245816A1
• Filed: 03/31/2005
• Published: 11/03/2005
• Est. Priority Date: 03/31/2004
• Status: Active Grant

• Current Assignee: Siemens Healthcare GMBH (Siemens AG)
• Original Assignee: Siemens AG
• Inventors: Candidus, Yvonne, Feiweier, Thorsten, Horger, Wilhelm, Lazar, Razvan, Schon, Lothar, Huber, Jurgen, Schmitt, Melanie
• Granted Patent: US 7,492,156 B2
• Time in Patent Office: Days
• US Class Current: 600/420
• CPC Class Codes: G01R 33/28 Details of apparatus provided for in groups G01R33/44 - G01R33/64
• CPC Class Codes: G01R 33/34 Constructional details, e.g. resonators , specially adapted to MR
• CPC Class Codes: G01R 33/5659 caused by a distortion of the RF magnetic field, e.g. spatial inhomogeneities of the RF magnetic field G01R33/56509, G01R33/56518, G01R33/56536 take precedence
• CPC Class Codes: Y10T 29/49 Method of mechanical manufacture

Abstract

A dielectric element is formed of a dielectric material exhibiting a magnetic resonance relaxation time, with a relaxation agent incorporated in the dielectric material that reduces the relaxation time of the dielectric material. The dielectric element is adapted for placement on a subject while magnetic resonance data are acquired from the subject, and locally influences the B₁ field distribution in the subject during the acquisition of magnetic resonance data.

Claims

1. A method for generating a magnetic resonance exposure of an examination subject comprising the steps of:

in a dielectric element exhibiting a relaxation time selected from the group consisting of a T₁ relaxation time and a T₂ relaxation time, incorporating a relaxation agent that reduces said relaxation time;

positioning said dielectric on an examination subject; and

obtaining magnetic resonance data from said subject with said dielectric element placed thereon in a data acquisition sequence that includes generating a B₁ field that produces a B₁ field distribution in said subject, and locally influencing said B₁ field distribution with said dielectric element placed on said subject.

2. A method for manufacturing a dielectric element adapted for placement on an examination subject during acquisition of magnetic resonance data from the subject by locally influencing distribution of a B₁ field in said subject with said dielectric element, said method comprising the steps of:

in a dielectric material exhibiting a relaxation time selected from the group consisting of a T₁ relaxation time and a T₂ relaxation time, incorporating a relaxation agent that reduces said relaxation time; and

fabricating said dielectric material with said relaxation agent incorporated therein into a dielectric element adapted for placement on a subject during acquisition of magnetic resonance data from the subject.

3. A method as claimed in claim 2 comprising employing a paramagnetic substance as said relaxation agent.

4. A method as claimed in claim 3 comprising forming said paramagnetic substance from at least one element selected from the group of elements consisting of gadolinium, europium, iron, chromium, nickel, copper and manganese.

5. A method as claimed in claim 4 comprising integrating said chemical element into a complex.

6. A method as claimed in claim 3 comprising employing a gadolinium complex as said paramagnetic substance.

7. A method as claimed in claim 2 comprising formulating said dielectric material with said relaxation incorporated therein as a dielectric filling;

and

surrounding said dielectric filling with an outer solid shell.

8. A method as claimed in claim 7 comprising forming said outer solid shell from an organic polymer.

9. A method as claimed in claim 8 comprising selecting said organic polymer from the group consisting of soft PVC, polyethylene and polypropylene.

10. A method as claimed in claim 7 comprising forming said outer solid shell as a laminate of at least two layers.

11. A method as claimed in claim 10 comprising forming at least one of said at least two layers from a material selected from the group consisting of organic polymers and fabrics.

12. A method as claimed in claim 2 comprising incorporating said relaxation agent in said dielectric material by incorporating said relaxation agent in a gel and incorporating said gel in said dielectric material, and surrounding said dielectric material with a diffusion-resistant covering.

13. A method as claimed in claim 12 comprising employing an aqueous gel as said gel.

14. A method as claimed in claim 12 comprising employing a gel having a sodium polyacrylate base as said gel.

15. A method as claimed in claim 14 comprising forming said gel having a sodium polyacrylate base from a dry sodium polyacrylate powder having a maximum particle size of 0.5 mm.

16. A method as claimed in claim 14 comprising forming said gel having a sodium polyacrylate base from a dry sodium polyacrylate powder having a maximum particle size of below approximately 0.2 mm.

17. A method as claimed in claim 12 comprising incorporating said gel into said dielectric material in a concentration in a range between 3 and 10 weight percent of said dielectric material with said gel incorporated therein.

18. A method as claimed in claim 12 comprising incorporating said gel into said dielectric material in a concentration of 5 weight percent of said dielectric material with said gel incorporated therein.

19. A method as claimed in claim 12 comprising incorporating a preservative in said gel.

20. A method as claimed in claim 19 comprising incorporating said preservative in said gel in an amount forming more than 20 weight percent of said gel.

21. A method as claimed in claim 19 comprising incorporating said preservative in said gel in an amount forming approximately 25 weight percent of said gel.

22. A method as claimed in claim 19 comprising employing a preservative selected from the group consisting of 1,2-propanediol, ethanol and 2-propanol as said preservative.

23. A dielectric element adapted for positioning on a subject during acquisition of magnetic resonance data from the subject to locally influence a distribution of a B₁ field in the subject, comprising:

dielectric material exhibiting a relaxation time selected from the group consisting of T₁ relaxation time and T₂ relaxation time; and

a relaxation agent incorporated in said dielectric material that reduces said relaxation time.

24. A dielectric element as claimed in claim 23 wherein said relaxation agent comprises a paramagnetic substance.

25. A dielectric element as claimed in claim 24 wherein said paramagnetic substance is at least one chemical element selected from the group consisting of gadolinium, europium, iron, chromium, nickel, copper and manganese.

27. A dielectric element as claimed in claim 23 wherein said relaxation agent comprises a gadolinium complex.

28. A dielectric element as claimed in claim 23 wherein said dielectric material with said relaxation agent incorporated therein forms a dielectric filling, and comprising an outer solid shell surrounding said dielectric filling.

29. A dielectric element as claimed in claim 28 wherein said outer solid shell is comprised of an organic polymer.

30. A dielectric element as claimed in claim 29 wherein said organic polymer is selected from the group consisting of soft PVC, polyethylene and polypropylene.

31. A dielectric element as claimed in claim 28 wherein said outer solid shell comprises a laminate of at least two layers.

32. A dielectric element as claimed in claim 31 wherein at least one of said at least two layers is comprised of a material selected from the group consisting of organic polymers and fabrics.

33. A dielectric element as claimed in claim 23 comprising a gel in which said relaxation agent is incorporated, said gel being incorporated in said dielectric material, and wherein said dielectric element comprises a diffusion-resistant covering surrounding said dielectric material.

34. A dielectric element as claimed in claim 27 wherein said gel is an aqueous gel.

35. A dielectric element as claimed in claim 33 wherein said gel is a gel having a sodium polyacrylate base.

36. A dielectric element as claimed in claim 35 wherein said gel having said sodium polyacrylate base is formed from a dry sodium polyacrylate powder having a maximum particle size of 0.5 mm.

37. A dielectric element as claimed in claim 35 wherein said gel having said sodium polyacrylate base is formed from a dry sodium polyacrylate powder having a maximum particle size below approximately 0.2 mm.

38. A dielectric element as claimed in claim 33 wherein said gel is incorporated in said dielectric material in a concentration in a range between 3 and 10 weight percent of said dielectric material with said gel incorporated therein.

39. A dielectric element as claimed in claim 33 wherein said gel is incorporated in said dielectric material in a concentration of 5 weight percent of said dielectric material with said gel incorporated therein.

40. A dielectric element as claimed in claim 33 wherein said gel comprises a preservative.

41. A dielectric element as claimed in claim 40 wherein said gel comprises said preservative in a portion of more than 20 weight percent of said gel.

42. A dielectric element as claimed in claim 40 wherein said gel comprises said preservative in a portion of approximately 25 weight percent of said gel.

43. A dielectric element as claimed in claim 40 wherein said preservative is a preservative selected from the group consisting of 1,2-propanediol, ethanol and 2-propanol.

26. A dielectric element as claimed in claim 26 wherein said element in said paramagnetic substance is integrated into a complex.