Multi-contrast delayed enhancement cardiac magnetic resonance imaging

• US 9,395,431 B2
• Filed: 05/01/2008
• Issued: 07/19/2016
• Est. Priority Date: 05/01/2008
• Status: Active Grant

• Current Assignee: Sunnybrook Health Sciences Centre
• Original Assignee: Sunnybrook Health Sciences Centre
• Inventors: Detsky, Jay S., Wright, Graham A.
• Primary Examiner(s): Le, Long V
• Assistant Examiner(s): IMPINK, BRADLEY GERALD
• Application Number:
  US12/113,675
• Publication Number:
  US 20090275822A1
• Time in Patent Office: 3,001 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: A61B 5/055 involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
• CPC Class Codes: A61B 5/7285 for synchronising or triggering a physiological measurement or image acquisition with a physiological event or waveform, e.g. an ECG signal A61B6/5205, A61B6/541, A61B8/5207, A61B8/543 take precedence
• CPC Class Codes: G01R 33/50 based on the determination of relaxation times , e.g. T1 measurement by IR sequences; T2 measurement by multiple-echo sequences
• 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 33/5614 using a fully balanced steady-state free precession [bSSFP] pulse sequence, e.g. trueFISP
• CPC Class Codes: G01R 33/56325 Cine imaging
• CPC Class Codes: G01R 33/56509 due to motion, displacement or flow, e.g. gradient moment nulling G01R33/567 takes precedence
• 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

A series of MR image frames are acquired that depict a subject'"'"'s heart at successive cardiac phases. Delayed enhancement of infarcted myocardium is depicted in some of the image frames by administering a contrast agent prior to data acquisition. Data acquisition is performed in a single breath hold by producing an RF inversion pulse followed by segments of SSFP pulse sequences during a succession of cardiac gated heart beats. The acquired MR image frames depict contrast between blood, viable myocardium and nonviable myocardium, and they depict left ventricle wall thickness and wall thickening throughout the cardiac cycle.

Claims

1. A method for producing a series of cardiac gated magnetic resonance images of a subject'"'"'s heart, the steps comprising:

a) administering a contrast agent to the subject;

b) producing a gating signal that indicates the start of the subject'"'"'s cardiac cycle;

c) producing a radio frequency (RF) inversion pulse that inverts spin magnetization throughout a field of view a preset time after the gating signal is produced;

d) acquiring k-space data as a series of data segments at successive cardiac phases after the RF inversion pulse is produced using a plurality of steady-state free precession (SSFP) pulse sequences during a time period in which the inverted spin magnetization recovers such that some data segments in the series of data segments are acquired when tissue contrast is changing and other data segments in the series of data segments are acquired when tissue contrast is no longer substantially changing;

e) repeating steps b) through d) until a desired amount of k-space data is acquired in each data segment;

f) reconstructing a series of image frames depicting the heart at a succession of cardiac phases using the k-space data acquired in the series of data segments, and in which images in the series of image frames reconstructed from the data segments acquired when tissue contrast is changing depict a time-varying tissue contrast of the heart, and in which images in the series of image frames reconstructed from the data segments acquired when tissue contrast is no longer substantially changing depict cardiac wall motion; and

g) producing a T₁* map by;

i) determining for a given pixel location in the T₁* map, a T₁* value by fitting magnitude values from corresponding pixel locations in the series of image frames reconstructed in step f) to a signal model that relates magnitude values to T₁*; and

ii) setting magnitude values for each given pixel location in the T₁* map to the corresponding T₁* value determined in step g)i).

2. The method as recited in claim 1 which further includes:

h) performing a magnetization equalization pulse sequence during a cardiac cycle preceding the performance of step c), the magnetization equalization pulse sequence including performing an RF inversion pulse that inverts spin magnetization throughout the field of view the preset time after the gating signal is produced followed by an SSFP pulse sequence in which no k-space data is acquired.

3. The method as recited in claim 1 in which the preset time interval in step c) is selected such that images that depict optimal contrast between viable and nonviable myocardium tissues of the heart are acquired during mid-diastole of each cardiac cycle.

4. The method as recited in claim 1 in which the desired amount of k-space data in each data segment is acquired in step e) by performing a number of SSFP pulse sequences during a single breath hold of the subject.

5. A method for producing a series of delayed contrast enhanced magnetic resonance images of a subject'"'"'s heart, the steps comprising:

a) producing a gating signal that indicates the start of the subject'"'"'s cardiac cycle;

b) producing a radio frequency (RF) inversion pulse that inverts spin magnetization throughout a field of view a preset time after the gating signal is produced;

c) acquiring k-space data as a series of data segments at successive cardiac phases after the RF inversion pulse is produced using a plurality of steady-state free precession (SSFP) pulse sequences during a time period in which the inverted spin magnetization recovers such that some data segments in the series of data segments are acquired when tissue contrast is changing and other data segments in the series of data segments are acquired when tissue contrast is no longer substantially changing;

d) repeating steps a) through c) until a desired amount of k-space data is acquired in each data segment;

e) reconstructing a series of image frames depicting the heart at a succession of cardiac phases using the k-space data acquired in the series of data segments, and in which images in the series of image frames reconstructed from the data segments acquired when tissue contrast is changing depict a time-varying tissue contrast of the heart, and in which images in the series of image frames reconstructed from the data segments acquired when tissue contrast is no longer substantially changing depict cardiac wall motion; and

f) producing a T₁* map by;

i) determining for a given pixel location in the T₁* map, a T₁* value by fitting magnitude values from corresponding pixel locations in the series of image frames reconstructed in step e) to a signal model that relates magnitude values to T₁*; and

ii) setting magnitude values for each given pixel location in the T₁* map to the corresponding T₁* value determined in step f)i).

6. The method as recited in claim 5 which includes:

g) performing a magnetization equalization pulse sequence during a cardiac cycle preceding the performance of step b), the magnetization equalization pulse sequence including performing an RF inversion pulse that inverts spin magnetization throughout the field of view the preset time after the gating signal is produced followed by an SSFP pulse sequence in which no k-space data is acquired.

7. The method as recited in claim 5 in which the preset time interval in step b) is selected such that images that depict best contrast between viable and nonviable myocardium tissues of the heart are acquired during the mid-diastole of each cardiac cycle.

8. The method as recited in claim 5 in which the desired amount of k-space data in each data segment is acquired in step d) by performing a number of SSFP pulse sequences during a single breath hold of the subject.

9. A method for determining a health of a subject'"'"'s heart, the steps comprising:

a) acquiring a series of image frames of the subject'"'"'s heart with a magnetic resonance imaging (MRI) system by performing a scan which includes;

a)i) administering a contrast agent to the subject;

a)ii) performing a cardiac gated, segmented acquisition during each of a series of cardiac cycles and after the application of an inversion radio frequency (RF) pulse during each cardiac cycle to acquire a corresponding series of image frame data sets having tissue contrast that differs as a function of inversion recovery time (TI) after the inversion RF pulse; and

a)iii) reconstructing a series of image frames from the corresponding image frame data sets;

b) producing a T₁* map indicating the inversion recovery time of tissues depicted in the image frames; and

c) producing a steady state map indicating fully recovered signal values of tissues depicted in the image frames.

10. The method as recited in claim 9 in which step a)ii) is performed using a steady state free precession (SSFP) pulse sequence to direct the MRI system.

11. The method as recited in claim 9 which further includes:

d) selecting from the series of image frames, one or more image frames that depicts optimal contrast between infarcted myocardium tissue and normal myocardium tissue.

12. The method as recited in claim 9 which further includes:

e) producing a segmented image frame by using the T₁* map and the steady state map as input to a fuzzy clustering process.

13. The method as recited in claim 12 in which the segmented image frame is segmented to indicate normal myocardial tissues, infarcted myocardial tissues, and blood.

14. The method as recited in claim 13 in which the normal myocardial tissues, infarcted myocardial tissues, and blood are indicated in the segmented image frame by color coding pixels in the segmented image frame.

15. The method as recited in claim 9 in which step b) includes producing the T₁* map by:

b)i) selecting a set of image frames from the reconstructed series of image frames that depict recovery of signals at each pixel location therein over a period of time following the inversion RF pulse;

b)ii) fitting recovery curves to the signals at corresponding pixel locations in the selected set of image frames; and

b)iii) calculating a T₁* value for each pixel location in the T₁* map from the recovery curve for a corresponding pixel location in the set of image frames.

16. The method as recited in claim 15 in which step c) includes producing the steady state map by calculating a steady state value for each pixel location in the steady state map from the recovery curve for a corresponding pixel location in the set of image frames.

17. The method as recited in claim 15 in which step b)i) further includes registering the selected set of image frames to align tissues depicted in the selected set of image frames at substantially same pixel locations in each of the image frames in the selected set of image frames.