Quadruple inversion recovery for quantitative contrast-enhanced black blood imaging

• US 20040133098A1
• Filed: 12/18/2003
• Published: 07/08/2004
• Est. Priority Date: 12/19/2002
• Status: Active Grant

• Current Assignee: University of Washington, Washington University In St Louis
• Original Assignee: University of Washington
• Inventors: Yuan, Chun, Yarnykh, Vasily L.
• Granted Patent: US 7,715,900 B2
• Time in Patent Office: Days
• US Class Current: 600/419
• CPC Class Codes: G01R 33/5601 involving use of a contrast agent for contrast manipulation, e.g. a paramagnetic, super-paramagnetic, ferromagnetic or hyperpolarised contrast agent
• CPC Class Codes: G01R 33/5607 by reducing the NMR signal of a particular spin species, e.g. of a chemical species for fat suppression, or of a moving spin species for black-blood imaging

Abstract

A contrast enhancement (CE) agent is infused into blood flowing through a site that is to be imaged with magnetic resonance imaging (MRI). Two double inversion procedures are carried out, forming a quadruple inversion recovery (QIR) pulse sequence. Each double inversion procedure comprises a non-selective and slice-selective inversion RF pulse. The first double inversion procedure is followed by a first predefined inversion delay period, TI₁, and the second procedure by a second predefined inversion delay period, TI₂. A black-blood image can thus be produced in which blood appears consistently black and tissues surrounding the blood, such as a vessel wall, heart, atherosclerotic plaque, or thrombus, are clearly visible. Unlike the prior art black-blood imaging technique, the QIR method does not require a precise knowledge of the T₁ of the blood carrying the CE agent in order to suppress the signal and artifacts caused by the blood flowing through the site.

Claims

1. A method for suppressing a signal from flowing blood in a signal used for magnetic resonance imaging (MRI) of a site in a subject, comprising the steps of:

(a) generating a sequence of radiofrequency (RF) pulses, a total number of the said RF pulses being an even number at least equal to four;

(b) applying said RF pulses to the subject so that the said RF pulses are grouped into a plurality of double inversion procedures, each double inversion procedure including a non-selective RF pulse targeted to the subject and a slice-selective RF pulse that is targeted to one of a slice, a group of slices, and a three-dimensional slab at the site, wherein one of the non-selective RF pulse and the slice-selective RF pulse immediately follows the other of the non-selective RF pulse and the slice-selective RF pulse;

(c) waiting a predefined time period after each of the said double inversion procedures; and

(d) after the predefined time period following a last of the said double inversion procedures, acquiring a signal that is processed to produce an image of the site, said signal from the flowing blood being substantially suppressed in the signal used to produce the image of the site.

2. The method of claim 1, wherein the predefined time periods are determined so that the longitudinal magnetization of flowing blood is substantially zero when the signal used to produce the image is acquired.

3. The method of claim 1, further comprising the step of infusing a contrast-enhancing agent in the subject before generating the sequence of RF pulses, wherein the predefined time periods are determined so that the signal from flowing blood is sufficiently suppressed at any value of a T₁ parameter affected by the infusion of the contrast-enhancing agent.

4. The method of claim 1, wherein the sequence of RF pulses comprise a first double inversion procedure and a second double inversion procedure, the first double inversion procedure being followed by a first predefined time period, TI₁, and a second double inversion procedure being followed by a second predefined time period, TI₂.

5. The method of claim 4, wherein the longitudinal magnetization of the blood is defined as a function of:

(a) a repetition time, TR;

(b) a T₁ parameter for the flowing blood;

(c) the first predefined time period TI₁; and

(d) the second predefined time period TI₂.

6. The method of claim 5, wherein the first and the second predefined time periods, TI₁ and TI₂, are determined so that the longitudinal magnetization of the flowing blood is substantially zero over a wide range of the T₁ parameter.

13. A memory medium storing machine instructions for carrying out the steps of claim 1.

7. A method for suppressing the signal from flowing fluid in magnetic resonance imaging (MRI) after infusion of a contrast agent, comprising the steps of:

(a) carrying out a first double inversion procedure that includes applying in rapid succession and in either order a non-selective inversion RF pulse and a slice-selective inversion RF pulse, said slice-selective inversion RF pulse being targeted at one of a slice, a group of slices, and a three-dimensional slab;

(b) waiting a first predefined inversion delay period;

(c) carrying out a second double inversion procedure that includes again applying in rapid succession and in either order a non-selective inversion RF pulse and a slice-selective inversion RF pulse targeted at said one of the slice, the group of slices, and the three-dimensional slab;

(d) waiting a second predefined inversion delay period; and

(e) acquiring a signal for processing to produce the image in which the signal from flowing fluid appears suppressed and a tissue surrounding the fluid is consistently visible.

8. The method of claim 7, wherein the fluid comprises blood, and the tissue surrounding the fluid comprises one of a wall of a blood vessel and a heart.

9. The method of claim 7, wherein the first predefined inversion delay period and the second predefined inversion delay period are selected so that a longitudinal magnetization of the fluid is substantially zero when the signal is acquired for processing to produce the image.

10. The method of claim 7, wherein a longitudinal magnetization of the fluid is defined as a function of:

(a) a repetition time, TR;

(b) a T₁ parameter for the fluid;

(c) the first predefined inversion delay period; and

(d) the second predefined inversion delay period.

11. The method of claim 7, wherein the contrast enhancement agent includes but not limited to a gadolinium derivative.

12. The method of claim 7, wherein the use of the first and the second double inversion procedures suppresses a contribution of the fluid to the image over a wide range of T₁, for the fluid with the contrast enhancement agent infused therein.

14. A method for contrast-enhanced black-blood magnetic resonance imaging (MRI) so that tissue surrounding blood is clearly visible and the blood is consistently black in an image of a site, comprising the steps of:

(a) infusing a contrast enhancement agent into the blood so that the blood carrying a portion of the contrast enhancement agent is flowing through the site to be imaged;

(b) carrying out a first double inversion procedure;

(c) waiting a first predefined inversion delay period;

(d) carrying out a second double inversion procedure, each of the first and the second double inversion procedures including the steps of applying in rapid succession an in either order a non-selective inversion RF pulse and a slice-selective inversion RF pulse, said slice-selective inversion RF pulse being targeted at one of a slice, a group of slices, and a three-dimensional slab at the site;

(e) waiting a second predefined inversion delay period; and

(f) acquiring a signal for processing to produce an image, in which the flowing blood is consistently black.

15. The method of claim 14, wherein the first and second predefined inversion delay periods are selectively determined so that a signal from the flowing blood is suppressed in the image over a relatively wide range of T₁ values for the blood carrying the portion of the contrast enhancement agent.

16. The method of claim 14, wherein a longitudinal magnetization of the flowing blood is substantially zero at a time when the signal is acquired.

17. The method of claim 14, wherein said longitudinal magnetization varies as a functions of the first predefined inversion delay period, the second predefined inversion delay period, a repetition time (TR), and a T₁ value of the blood carrying the portion of the contrast enhancement agent.

18. The method of claim 14, wherein the contrast enhancement agent comprises a gadolinium derivative.

19. The method of claim 14, further comprising the step of applying the first double inversion and the second double inversion, each followed by the predefined inversion delay periods, so that a signal is acquired for producing a non-enhanced image obtained before the contrast enhancement agent is infused into the blood.

20. The method of claim 19, wherein the said non-enhanced image is obtained with inversion delay periods and a repetition time (TR) that are the same as the inversion delay periods and the repetition time (TR) used when producing the image after the contrast enhancement agent was infused.

21. The method of claim 20, wherein the said non-enhanced image and the said image produced after the contrast enhancement was infused are used to quantitatively measure changes of signal intensities in tissues caused by the contrast enhancement agent.

22. A memory medium storing machine instructions for carrying out steps (b)-(d) of claim 14.

23. A pulse sequence for quadruple inversion-recovery magnetic resonance imaging of a site, comprising:

(a) a first double inversion pulse pair comprising in rapid succession and in either order a slice-selective inversion radiofrequency (RF) pulse and a non-selective inversion RF pulse;

(b) a first time delay period;

(c) a second double inversion pulse pair comprising in rapid succession and in either order a slice-selective inversion RF pulse and a non-selective inversion RF pulse;

(d) a second delay period; and

(e) an acquisition sequence comprising RF pulses and magnetic field gradient pulses for spatial encoding and readout of a signal for producing an image of the site.

24. The pulse sequence of claim 23, wherein the slice-selective inversion RF pulse and the non-selective inversion RF pulse produce at least a partial if not a complete inversion of longitudinal magnetization.

25. The pulse sequence of claim 23, wherein the first and the second delay periods are not equal.

26. The pulse sequence of claim 23, wherein the first and the second delay periods are selected to ensure that a magnetization of blood is substantially zero when the acquisition sequence occurs.

27. The pulse sequence of claim 23, further comprising more than two double inversion pulse pairs.

28. The pulse sequence of claim 23, wherein said non-selective inversion pulses are rectangular pulses.

29. The pulse sequence of claim 23, wherein said non-selective inversion pulses are adiabatic phase-modulated pulses.

30. The pulse sequence of claim 23, wherein said slice-selective inversion pulses are adiabatic phase-modulated pulses.

31. The pulse sequence of claim 23, wherein the said slice-selective pulses are targeted at one of a single slice, a group of slices, and a three-dimensional slab.

32. The pulse sequence of claim 23, wherein the said acquisition sequence is used for one of two-dimensional and three-dimensional data acquisition.

33. A system for carrying out quadruple inversion-recovery data acquisition, comprising:

(a) an MRI apparatus adapted for producing an image of a site; and

(b) a computer coupled to the MRI apparatus to control it, said computer including;

(i) a memory in which machine instructions are stored; and

(ii) a processor coupled to the memory, said processor executing the machine instructions to control the MRI apparatus to carry out a sequence of operations, including;

(1) generating and applying in rapid succession a pair of radiofrequency (RF) inversion pulses, one RF inversion pulse being selective and the other being non-selective;

(2) waiting for a first predefined delay period;

(3) again generating and applying in rapid succession the pair of RF inversion pulses, one of which is selective and the other of which is non-selective;

(4) waiting for a second predefined delay period; and

(5) acquiring a magnetic resonance signal for use in producing an image of the site.

34. The system of claim 33, wherein the machine instructions further cause the processor to determine the first and the second predefined delay periods so as to minimize a deviation of blood magnetization from zero, over a defined range of T₁ of blood at the site.

35. The system of claim 33, wherein the machine instructions further cause the processor to determine the first and the second predefined delay periods so that blood magnetization at the site is substantially zero when the magnetic resonance signal is acquired.

36. The system of claim 33, wherein the machine instructions enable an operator to input the first and the second predefined delay periods.

37. The system of claim 33, wherein the machine instructions cause the processor to control the MRI apparatus so that the sequence is periodically repeated with a repetition time that is defined by an operator.

38. The system of claim 33, wherein the machine instructions cause the processor to enable an operator to selectively run the sequence in synchronization with a cardiac rhythm of a subject that is being imaged, with a period equal to at least one systolic period.