Dark blood delayed enhancement magnetic resonance viability imaging techniques for assessing subendocardial infarcts

• US 8,086,297 B2
• Filed: 12/17/2007
• Issued: 12/27/2011
• Est. Priority Date: 01/31/2007
• Status: Active Grant

• Current Assignee: Duke University, Siemens Medical Solutions USA Incorporated (Siemens AG)
• Original Assignee: Duke University
• Inventors: Rehwald, Wolfgang, Salerno, Michael
• Primary Examiner(s): KISH, JAMES M
• Application Number:
  US11/957,520
• Publication Number:
  US 20090005673A1
• Time in Patent Office: 1,471 Days
• Field of Search: 600/407, 600/410, 600/419, 600/420
• US Class Current: 600/420
• CPC Class Codes: A61B 5/055 involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
• CPC Class Codes: G01R 33/54 Signal processing systems, e.g. using pulse sequences ; Generation or control of pulse sequences; Operator console
• 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 33/5602 by filtering or weighting based on different relaxation times within the sample, e.g. T1 weighting using an inversion pulse
• 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
• CPC Class Codes: G01R 33/5608 Data processing and visualization specially adapted for MR, e.g. for feature analysis and pattern recognition on the basis of measured MR data, segmentation of measured MR data, edge contour detection on the basis of measured MR data, for enhancing measured MR data in terms of signal-to-noise ratio by means of noise filtering or apodization, for enhancing measured MR data in terms of resolution by means for deblurring, windowing, zero filling, or generation of gray-scaled images, colour-coded images or images displaying vectors instead of pixels image data processing or generation, in general G06T
• CPC Class Codes: G01R 33/5673 Gating or triggering based on a physiological signal other than an MR signal, e.g. ECG gating or motion monitoring using optical systems for monitoring the motion of a fiducial marker

Abstract

The technology herein provides a dark blood delayed enhancement technique that improves the visualization of subendocardial infarcts that may otherwise be disguised by the bright blood pool. The timed combination of a slice-selective and a non-selective preparation improves the infarct/blood contrast by decoupling their relaxation curves thereby nulling both the blood and the non-infarcted myocardium. This causes the infarct to be imaged bright and the blood and non-infarct to both be imaged dark. The slice-selective preparation occurs early enough in the cardiac cycle so that fresh blood can enter the imaged slice.

Claims

1. A magnetic resonance imaging method comprising:

injecting a live patient with a paramagnetic contrast agent that collects within dead heart tissue;

applying a nuclear magnetic resonance (NMR) slice-selective preparation pulse to the patient'"'"'s chest;

waiting a first delay time that is a function of both;

(a) healthy heart tissue longitudinal relaxation time T1 and (b) a second delay time such that the patient'"'"'s blood appears nulled based on the blood longitudinal relaxation time T1;

then applying a nuclear magnetic resonance non-spatially selective inversion preparation pulse to the patient'"'"'s chest;

then waiting the second delay time to allow blood the patient'"'"'s heart contained at the time of said slice-selective preparation pulse to be expelled from the patient'"'"'s heart;

then acquiring NMR echoes conditioned by the preparation pulses and first and second delay times so that magnetization of healthy heart tissue and blood are substantially the same; and

generating an image based on said acquired NMR echoes, wherein the image shows normal heart tissue and blood within the patient'"'"'s heart as the same color or intensity and shows the patient'"'"'s dead heart tissue as a different color or intensity.

2. The method of claim 1 further including using a specific combination of said first delay time and second delay time to force the magnetization of normal heart tissue and the blood within the patient'"'"'s heart to be substantially the same and to be substantially zero.

3. A cardiac imaging method comprising:

applying a preparation to a beating heart containing blood, the preparation comprising a slice-selective preparation pulse followed by a non-spatially selective inversion preparation pulse with a timed wait therebetween, said timed wait being a function of both (a) healthy heart tissue longitudinal relaxation time T1 and (b) a further delay such that blood which will be within the beating heart at the time of read out is nulled based on blood longitudinal relaxation time T1;

after waiting the second delay time to allow the patient'"'"'s heart to expel blood the heart contained at the time of said slice-selective preparation pulse, reading out nuclear magnetic resonance echoes from the beating heart at a time when relaxation of blood and non-infarcted myocardium are nulled together; and

generating an image from said echoes showing non-infarcted myocardium and blood as dark and infarcted myocardium as bright.

4. A cardiac imaging method comprising:

applying at least one slice-selective preparation pulse to a heart containing blood;

applying a slice-selective preparation pulse, then waiting a delay that is a function of both (a) healthy heart tissue longitudinal relaxation time T1 and (b) a second delay time such that the blood is nulled based on the blood longitudinal relaxation time T1, and then applying a non-spatially selective preparation pulse to the heart;

then waiting until blood within the heart at the time of the slice-selective preparation pulse has been expelled from the heart;

then reading out nuclear magnetic resonance (NMR) echoes from the heart at a time when relaxation of blood and non-infarcted myocardium are nulled together so that magnetization of healthy heart tissue and blood are substantially the same; and

generating an image, based on said read-out NMR echoes, showing non-infarcted myocardium and blood as dark and infarcted myocardium as bright.

5. The method of claim 4 wherein said slice-selective preparation pulse comprises a selective partial inversion pulse.

6. The method of claim 4 wherein said slice-selective preparation pulse comprises a saturation pulse.

7. The method of claim 4 wherein said slice-selective preparation pulse comprises an inversion pulse.

8. The method of claim 4 wherein said slice-selective preparation pulse comprises plural selective inversion pulses.

9. The method of claim 4 wherein said reading out comprises gradient echo readout.

10. The method of claim 4 wherein said reading out comprises turbo spin echo readout.

11. The method of claim 4 wherein said reading out comprises steady-state free precession (SSFP) readout.

12. A cardiac imaging method comprising:

applying at least one inversion pulse to a patient'"'"'s chest;

waiting a delay time that is a function of both (a) healthy heart tissue longitudinal relaxation time T1, and (b) blood longitudinal relaxation time T1;

then applying a second, non-spatially selective double inversion pulse to the patient'"'"'s chest;

then waiting until at least some of the blood present in the patient'"'"'s heart during the at least one inversion pulse has been expelled from the patient'"'"'s heart;

then reading out nuclear magnetic resonance (NMR) echoes from the heart at a time when relaxation of blood and non-infarcted myocardium are nulled together; and

generating an image, based on said read-out NMR echoes, showing non-infarcted myocardium and blood as dark and infarcted myocardium as bright.

13. The method of claim 12 wherein said at least one inversion pulse is slice-selective.

14. The method of claim 12 wherein said at least one inversion pulse is non-slice-selective.

15. The method of claim 12 wherein the reading out comprises one of spin echo readout, gradient echo readout and steady-state free precession (SSFP) readout.