Tissue mimicking elastography phantoms

• US 20040067591A1
• Filed: 10/04/2002
• Published: 04/08/2004
• Est. Priority Date: 10/04/2002
• Status: Abandoned Application

• Current Assignee: Wisconsin Alumni Research Foundation (University of Wisconsin System)
• Original Assignee: Wisconsin Alumni Research Foundation (University of Wisconsin System)
• Inventors: Frank, Gary R., Madsen, Ernest L.
• Application Number:
  US10/265,293
• Publication Number:
  US 20040067591A1
• Time in Patent Office: Days
• US Class Current: 436/8
• CPC Class Codes: A61B 5/055 involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
• CPC Class Codes: A61B 8/08 Detecting organic movements or changes, e.g. tumours, cysts, swellings A61B8/02 - A61B8/06 take precedence
• CPC Class Codes: A61B 8/485 involving measuring strain or elastic properties
• CPC Class Codes: A61B 8/587 Calibration phantoms models for medical purposes G09B23/28
• CPC Class Codes: Y10T 436/10 Composition for standardization, calibration, simulation, stabilization, preparation or preservation; processes of use in preparation for chemical testing
• CPC Class Codes: Y10T 436/24 Nuclear magnetic resonance, electron spin resonance or other spin effects or mass spectrometry

Abstract

Tissue mimicking materials for elastography phantoms have elastic, ultrasound, and magnetic resonance characteristics that are characteristic of human soft tissues and well suited for the calibration and performance assessment of elastography imaging systems. In one embodiment, the material is formed from a base material containing an oil dispersed within a gel matrix and at least one inclusion formed from a gel. In another embodiment, the material is formed from a gel-forming material suffused throughout an open-cell reticulated mesh matrix.

Claims

1. A tissue mimicking material for testing elastography imagers, comprising:

(a) a base material comprising an oil dispersed throughout a gel matrix formed from a gel-forming material; and

(b) at least one inclusion of a defined shape at least partially surrounded by the base material, the inclusion comprising the same gel-forming material as the base material, wherein the elastic contrast between the base material and the at least one inclusion is such that the elastic contrast between normal soft tissue and abnormal soft tissue is mimicked, making the tissue mimicking material suitable for use in testing elastography imagers.

2. The tissue mimicking material of claim 1 wherein the elastic contrast between the base material and the at least one inclusion is between about 1 and about 4.

3. The tissue mimicking material of claim 1 wherein the elastic contrast between the base material and the at least one inclusion is between about 1 and about 3.

4. The tissue mimicking material of claim 1 wherein the base material is elastically linear for strains of up to about 10 percent.

5. The tissue mimicking material of claim 1 wherein the speed of sound in the base material and the at least one inclusion is between about 1300 m/s and about 1650 m/s.

6. The tissue mimicking material of claim 1 wherein the T1 values of the base material and the at least one inclusion are between about 200 ms and about 1200 ms, and the T2 values of the base material and the at least one inclusion are between about 40 ms and about 700 ms.

7. The tissue mimicking material of claim 1 wherein the elastic contrast between the base material and the at least one inclusion varies by less than about 20% over a period of at least six months.

8. The tissue mimicking material of claim 1 wherein the gel-forming material comprises gelatin or a mixture of agar and gelatin.

9. The tissue mimicking material of claim 1 wherein the base material and the at least one inclusion both comprise an oil-in-gelatin dispersion and further wherein the concentration of oil in the base material differs from the concentration of oil in the at least one inclusion.

10. The tissue mimicking material of claim 1 wherein the gel-forming material in at least one of the base material or the at least one inclusion further comprises at least one additional additive selected from the group consisting of a crosslinking agent, an organic hydroxy compound, microscopic solid particles, a copper salt, a chelating agent, and an agent for inhibiting attack by microorganisms.

11. The tissue mimicking material of claim 1 wherein the oil is selected from the group consisting of safflower oil, olive oil, castor oil, and kerosene.

30. An elastography phantom comprising:

(a) an elastography phantom container enclosing an interior space; and

(b) the tissue mimicking material of claim 1 contained within the interior space of the container.

12. An abnormal tissue mimicking material for testing elastography imagers comprising an open-cell reticulated mesh material and a gel-forming material suffused into the mesh material, wherein the Young'"'"'s modulus of the abnormal tissue mimicking material mimics the Young'"'"'s modulus of abnormal soft tissue.

13. The abnormal tissue mimicking material of claim 12 wherein the Young'"'"'s modulus of the abnormal tissue mimicking material is between about 10 and about 300 kPa.

14. The abnormal tissue mimicking material of claim 12 wherein the open-cell reticulated mesh material is a polyether mesh or a polyurethane mesh.

15. The abnormal tissue mimicking material of claim 12 wherein the open-cell reticulated mesh material comprises between about 10 and about 30 cells per inch.

16. The abnormal tissue mimicking material of claim 12 wherein the gel-forming material comprises a material selected from the group consisting of gelatin, agar, a mixture of gelatin and agar, an emulsion of oil-in-gelatin, and an emulsion of oil in a mixture of agar and gelatin.

17. The abnormal tissue mimicking material of claim 12 wherein the gel-forming material comprises agar.

18. The abnormal tissue mimicking material of claim 17 wherein the material is elastically nonlinear for strains of up to about 10 percent.

19. The abnormal tissue mimicking material of claim 12 wherein the gel-forming material further comprises at least one additional additive selected from the group consisting of a crosslinking agent, an organic hydroxy compound, microscopic solid particles, a copper salt, a chelating agent, and an agent for inhibiting attack by microorganisms.

20. The abnormal tissue mimicking material of claim 12 wherein the gel-forming material comprises an inner volume comprising agar suffused into the mesh material and an outer shell comprising gelatin suffused into the mesh material, wherein the outer shell surrounds the inner volume.

21. The abnormal tissue mimicking material of claim 20 wherein the outer shell comprises a mixture of agar and gelatin.

23. A tissue mimicking material for testing elastography imagers, comprising:

(a) a base material comprising a gel-forming material; and

(b) at least one inclusion comprising the abnormal tissue mimicking material claim 12 at least partially surrounded by the base material, wherein the elastic contrast between the base material and the at least one inclusion is such that the elastic contrast between normal soft tissue and abnormal soft tissue is mimicked, making the tissue mimicking material suitable for use in testing elastography imagers.

24. The tissue mimicking material of claim 23 wherein the elastic contrast between the base material and the at least one inclusion is between about 1 and about 4.

25. The tissue mimicking material of claim 23 wherein the elastic contrast between the base material and the at least one inclusion is between about 1 and about 3.

26. The tissue mimicking material of claim 23 wherein the speed of sound in the base material and the at least one inclusion is between about 1300 and 1650 m/s.

27. The tissue mimicking material of claim 23 wherein the T1 values of the base material and the at least one inclusion are between about 200 ms and about 1200 ms and the T2 values of the base material and the at least one inclusion are between about 40 ms and about 200 ms.

28. The tissue mimicking material of claim 23 wherein the elastic contrast between the base material and the at least one inclusion varies by less than about 20% over a period of at least six months.

29. The tissue mimicking material of claim 23 wherein the gel-forming material in the base material is selected from the group consisting of gelatin, agar, or a mixture of gelatin and agar.

31. An elastography phantom comprising:

(a) an elastography phantom container enclosing an interior space; and

(b) the tissue mimicking material of claim 23 contained within the interior space of the container.

22. The abnormal tissue mimicking material of claim 22 wherein the inner volume is substantially spherically shaped and the outer shell has a plurality of spicules extending outward away from the inner volume.

32. A method for testing an elastography imager comprising, mapping local elastic strains of a tissue mimicking material to obtain a elastogram of the tissue mimicking material, the tissue mimicking material comprising:

(i) a base material comprising an oil dispersed throughout a gel matrix formed from a gel-forming material; and

(ii) at least one inclusion of a defined shape at least partially surrounded by the base material, the inclusion comprising the same gel-forming material as the base material, wherein the elastic contrast between the base material and the at least one inclusion is such that the elastic contrast between normal soft tissue and abnormal soft tissue is mimicked.

33. The method of claim 32 wherein the elastogram is an ultrasound elastogram or a magnetic resonance elastogram.

34. A method for testing an elastography imager comprising, mapping local elastic strains of a tissue mimicking material to obtain a elastogram of the tissue mimicking material, the tissue mimicking material comprising:

(i) a base material comprising a gel-forming material; and

(ii) at least one inclusion of a defined shape at least partially surrounded by the base material, the at least one inclusion comprising an open-cell reticulated mesh material and a gel-forming material suffused into the mesh material, wherein the elastic contrast between the base material and the at least one inclusion is such that the elastic contrast between normal soft tissue and abnormal soft tissue is mimicked.

35. The method of claim 34 wherein the elastogram is an ultrasound elastogram or a magnetic resonance elastogram.