Method and apparatus for quantitative bone matrix imaging by magnetic resonance imaging

• US 20050240096A1
• Filed: 05/19/2003
• Published: 10/27/2005
• Est. Priority Date: 05/17/2002
• Status: Active Grant

• Current Assignee: Children's Medical Center Corporation, The General Hospital Corporation (Mass General Brigham, Inc.)
• Original Assignee: Children's Medical Center Corporation, The General Hospital Corporation (Mass General Brigham, Inc.)
• Inventors: Wu, Yaotang, Glimcher, Melvin J., Ackerman, Jerome L.
• Granted Patent: US 7,574,248 B2
• Time in Patent Office: Days
• US Class Current: 600/410
• CPC Class Codes: A61B 5/055 involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
• CPC Class Codes: A61B 5/417 the bone marrow
• CPC Class Codes: A61B 5/4504 Bones A61B5/4547 takes precedence
• CPC Class Codes: A61B 5/4509 Bone density determination
• CPC Class Codes: G01R 33/4816 NMR imaging of samples with ultrashort relaxation times such as solid samples, e.g. MRI using ultrashort TE [UTE], single point imaging, constant time imaging
• CPC Class Codes: G01R 33/4828 Resolving the MR signals of different chemical species, e.g. water-fat imaging

Abstract

An apparatus and technique for measuring volumetric, 3-D bone organic matrix density is described. The techniques includes providing a first pulse sequence fragment selected to suppress at least two fluid resonance signals and providing a second pulse sequence fragment which images at least solid signals. In one embodiment, a series of RF pulses used to suppress fluid in the bone marrow spaces, particularly in cancellous bone tissue, is combined with solid state projection reconstruction magnetic resonance imaging (MRI) to provide a three-dimensional image of a bone in which the dominant signal arises substantially from solid organic bone matrix.

Claims

1. A method comprising:

(a) providing a first pulse sequence fragment selected to suppress at least two fluid resonance signals; and

(b) providing a second pulse sequence fragment which images at least solid signals.

2. The method of claim 1 wherein each of the at least two fluid resonance signals are provided having a frequency spectral width less than 500 Hertz (Hz).

3. The method of claim 1 wherein each of the at least two fluid resonance signals are provided having a frequency spectral width less than 400 Hertz (Hz).

4. The method of claim 1 wherein each of the at least two fluid resonance signals are provided having a frequency spectral width less than 300 Hertz (Hz).

5. The method of claim 1 wherein each of the at least two fluid resonance signals are provided having a frequency spectral width less than 200 Hertz (Hz).

6. The method of claim 1 wherein each of the at least two fluid resonance signals are provided having a frequency spectral width less than 100 Hertz (Hz).

7. The method of claim 1 wherein each of the at least two fluid resonance signals are provided having a frequency spectral width less than 50 Hertz (Hz).

8. The method of claim 2 wherein providing a first pulse sequence fragment comprises providing a first series of RF pulses and a first series of gradient pulses.

9. The method of claim 8 wherein providing a first series of RF pulses comprises:

providing a water selective pulse having an angle of about 90°

;

providing a water selective pulse having an angle of about 180°

;

providing a fat selective pulse having an angle of about 90°

; and

providing a fat selective pulse having an angle of about 180°

.

10. The method of claim 9 wherein providing the water selective 180°

pulse comprises providing the water selective 180°

pulse only in alternate scans.

11. The method of claim 9 wherein providing the fat selective 180°

pulse comprises providing the fat selective 180°

pulse only in alternate scans.

12. The method of claim 8 wherein providing the gradient pulse comprises providing the gradient pulse only in alternate scans.

13. A magnetic resonance imaging (MRI) system for obtaining a quantitative bone matrix density measure, the system comprising an MRI pulse sequence generator for providing a first pulse sequence fragment selected to suppress at least two fluid resonance signals and for providing a second pulse sequence fragment which images at least solid signals.

14. The MRI system of claim 13 wherein said MRI pulse sequence generator comprises:

a fluid suppression processor which generates the first pulse sequence fragment selected to suppress at least two fluid resonance signals; and

a solid imaging processor which generates the second pulse sequence fragment which images at least solid signals.

15. The system of claim 14 wherein said fluid suppression processor generates a pulse sequence fragment which suppresses at least two fluid resonance signals having a frequency spectral width less than about 1000 Hertz (Hz).

16. The system of claim 14 wherein said fluid suppression processor generates a pulse sequence fragment which suppresses at least two fluid resonance signals having a frequency spectral width less than about 500 Hertz (Hz).

17. The system of claim 14 wherein said fluid suppression processor generates a pulse sequence fragment which suppresses at least two fluid resonance signals having a frequency spectral width less than about 400 Hertz (Hz).

18. The system of claim 14 wherein said fluid suppression processor generates a pulse sequence fragment which suppresses at least two fluid resonance signals having a frequency spectral width less than about 300 Hertz (Hz).

19. The system of claim 14 wherein said fluid suppression processor generates a pulse sequence fragment which suppresses at least two fluid resonance signals having a frequency spectral width less than about 200 Hertz (Hz).

20. The system of claim 14 wherein said fluid suppression processor generates a pulse sequence fragment which suppresses at least two fluid resonance signals having a frequency spectral width less than about 100 Hertz (Hz).

21. The system of claim 14 wherein said fluid suppression processor generates a pulse sequence fragment which suppresses at least two fluid resonance signals having a frequency spectral width less than about 50 Hertz (Hz).

22. The system of claim 14 wherein said first pulse sequence fragment comprises a first series of RF pulses and a first series of gradient pulses.

23. The system of claim 22 wherein said first series of RF pulses comprises:

a water selective pulse having an angle of about 90°

pulse;

a water selective pulse having an angle of about 180°

;

a fat selective pulse having an angle of about 90°

; and

a fat selective pulse having an angle of about 180°

.

24. The system of claim 23 wherein said first series of RF pulses comprises the water selective 180°

pulse only in alternate scans.

25. The system of claim 23 wherein said first series of RF pulses comprises the fat selective 180°

pulse only in alternate scans.

26. The method of claim 22 wherein the gradient pulse occurs only in alternate scans.

27. An apparatus comprising:

a magnetic resonance imaging (MRI) device; and

a pulse sequence processor, coupled to said MRI device, said pulse sequence processor for providing to said MRI device a first pulse sequence fragment selected to suppress at least two fluid resonance signals and for providing to said MRI device a second pulse sequence fragment which images at least solid signals.

28. A method of measuring bone organic matrix density in a bone using magnetic resonance imaging (MRI), the method comprising:

positioning the bone in a substantially static magnetic field;

subjecting the bone to a first pulse sequence fragment selected to suppress at least two fluid resonance signals;

subjecting the bone to a second pulse sequence fragment; and

acquiring RF signals emitted by the bone while the bone is subjected to the second pulse sequence fragment.

29. The method of claim 28 further comprising:

processing the RF signals to generate data representative of the bone matrix density.

33. The method of claim 29 further comprising combining the bone organic matrix density data with bone mineral data to obtain a measure of the degree of mineralization of the bone.

30. A method of measuring bone organic matrix density and bone mineral density in a bone using magnetic resonance imaging (MRI), the method comprising:

positioning the bone in a substantially static magnetic field;

subjecting the bone to a first pulse sequence fragment selected to suppress at least two fluid resonance signals;

subjecting the bone to a second pulse sequence fragment; and

acquiring RF signals emitted by the bone while the bone is subjected to the second pulse sequence fragment;

subjecting the bone to a third pulse sequence fragment; and

acquiring RF signals emitted by the bone while the bone is subjected to the third pulse sequence fragment.

31. The method of claim 30 wherein the first and second pulse sequence fragments excite protons in the bone and the third pulse sequence fragment excites phosphorus in the bone, and the emitted signals are processed to generate data representative of the bone organic matrix density and the bone mineral density.

32. The method of claim 31 further comprising combining the bone mineral density data and the bone organic matrix density data to obtain a measure of the degree of mineralization of the bone.