NON-CONTRAST MRI WITH DIFFERENTIATION OF ISCHEMIC, INFARCT AND NORMAL TISSUE

• US 20140050379A1
• Filed: 08/16/2012
• Published: 02/20/2014
• Est. Priority Date: 08/16/2012
• Status: Active Grant

• Current Assignee: Toshiba Medical Systems Corporation (Canon Inc.)
• Original Assignee: Toshiba Medical Systems Corporation (Canon Inc.), Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: MIYAZAKI, MITSUE, Hoshino, Tsutomu, Zhou, Xiangzhi
• Granted Patent: US 9,545,206 B2
• Time in Patent Office: Days
• US Class Current: 382/131
• CPC Class Codes: A61B 2576/023 for the heart
• CPC Class Codes: A61B 5/0263 using NMR
• CPC Class Codes: A61B 5/055 involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
• CPC Class Codes: A61B 5/7289 Retrospective gating, i.e. associating measured signals or images with a physiological event after the actual measurement or image acquisition, e.g. by simultaneously recording an additional physiological signal during the measurement or image acquisition
• CPC Class Codes: G01R 33/56366 Perfusion imaging
• CPC Class Codes: G06T 2207/30048 Heart; Cardiac
• CPC Class Codes: G06T 2207/30104 Vascular flow; Blood flow; Perfusion
• CPC Class Codes: G06T 7/0016 involving temporal comparison

Abstract

Elicited MRI signals are processed into MR image data in conjunction (a) with use of an initial spatially-selective RF tag pulse (tag-on) and (b) without use of an initial spatially-selective NMR RF tag pulse (tag-off) in respectively corresponding data acquisition subsequences. Multi-dimensional tag-on and tag-off data acquisition subsequences are used for each of plural time-to-inversion (TI) intervals without using an injected contrast agent. Acquired image data sets are subtracted for each TI interval to produce difference values as a function of time representing blood perfusion for the ROI that differentiates between normal, ischemic and infarct tissues.

Claims

1. A magnetic resonance imaging (MRI) system comprising:

an MRI gantry having static and gradient magnet assemblies and at least one radio frequency (RF) coil defining an image volume into which a patient region of interest (ROI) can be disposed;

MRI control circuits connected to control components within said MRI gantry and configured to effect MRI data acquisition sequences of RF and gradient magnetic pulses which elicit MRI signals from patient tissue when an ROI is disposed therein, to acquire and process said elicited MRI signals into MR image data in conjunction (a) with use of an initial spatially-selective nuclear magnetic resonance (NMR) RF tag pulse (tag-on) in a data acquisition subsequence and (b) without use of an initial spatially-selective NMR RF tag pulse (tag-off) in a data acquisition subsequence;

said MRI control circuits being configured to

(a) acquire multi-dimensional MR k-space data for a patient ROI using said tag-on and tag-off data acquisition subsequences for each of plural time to inversion (TI) intervals without using an injected contrast agent;

(b) reconstruct said acquired k-space data into spatial domain tag-on and tag-off MR image data;

(c) subtract said acquired tag-off and tag-on MR image data for each of plural TI intervals to produce difference image data as a function of time representing blood perfusion in said ROI having a corresponding flow time and/or relative peak blood flow magnitude, or lack thereof, for said ROI which differentiates between normal, ischemic and infarct tissues; and

(d) store and/or display perfusion data of the ROI having values which are different for normal, ischemic and infarct tissues.

2. An MRI system as in claim 1, wherein said display image data for said ROI at each of plural TI intervals defines a plot of relative blood flow as a function of time.

3. An MRI system as in claim 2, wherein said MRI control circuits are configured to acquire said peak blood flow time and/or relative peak blood flow magnitude values for each of plural myocardium ROIs.

4. An MRI system as in claim 3, wherein said MRI control circuits are configured to display superimposed plots of relative blood flow as a function of time for said plural ROIs.

5. An MRI system as in claim 3, wherein at least one of said ROIs represents a segment of myocardium assigned to one of plural predetermined segments of a Bull'"'"'s Eye display of myocardium.

6. An MRI system as in claim 1, wherein said difference values as a function of time produce peak blood flow time and/or relative peak MR signal strength data, or lack thereof, for said ROI which also differentiates revascularized infarct tissue from normal, ischemic and infarct tissues, and wherein said MRI control circuits are configured to store and/or display image data of the ROI having values which are different for revascularized, normal, ischemic and infarct tissue.

7. An MRI system as in claim 1, wherein said tag-on data acquisition subsequences are effected alternately with said tag-off data acquisition sequences.

8. An MRI system as in claim 1, wherein said peak blood flow time for normal tissue has an earlier occurring peak flow time as compared to the peak blood flow time for ischemic tissue, and wherein said MRI control circuits are configured to distinguish between normal and ischemic tissue based on this temporal difference.

9. An MRI system as in claim 8, wherein said peak blood flow time for revascularized tissue has an earlier occurring peak flow time as compared to the peak blood flow time for normal tissue and/or ischemic tissue, and wherein said MRI control circuits are configured to identify revascularized tissue based on this temporal difference.

10. An MRI system as in claim 1, wherein said relative peak MR signal strength value for normal tissue has a relatively higher peak blood flow value as compared to the peak MR blood flow value for ischemic tissue, and wherein said MRI control circuits are configured to distinguish between normal and ischemic tissue based on this difference in relative signal magnitude.

11. A magnetic resonance imaging (MRI) method comprising:

(a) acquiring multi-dimensional MR k-space data for a patient ROI using RF tag-on and RF tag-off data acquisition subsequences for each of plural time to inversion (TI) intervals without using an injected contrast agent;

(b) reconstructing said acquired k-space data into spatial domain tag-on and tag-off MR image data;

(c) subtracting said acquired tag-off and tag-on MR image data for each of plural TI intervals to produce difference image data as a function of time representing peak blood flow time and/or relative peak blood flow magnitude data, or lack thereof, for said ROI which differentiates between normal, ischemic and infarct myocardial tissues; and

(d) storing and/or displaying image data of the ROI having values which are different for normal, ischemic and infarct tissues.

12. An MRI method as in claim 11, wherein said display image data for said ROI at each of plural TI intervals defines a plot of relative blood flow as a function of time.

13. An MRI method as in claim 12, wherein said peak blood flow time and/or relative peak blood flow magnitude values are acquired for each of plural myocardium ROIs.

14. An MRI method as in claim 13, including displaying superimposed plots of relative blood flow as a function of time for said plural ROIs.

15. An MRI method as in claim 13, wherein at least one of said ROIs represents a segment of myocardium assigned to one of plural predetermined segments of a Bull'"'"'s Eye display of myocardium.

16. An MRI method as in claim 11, wherein said difference values as a function of time produce peak blood flow time and/or relative peak MR signal strength data, or lack thereof, for said ROI which also differentiates revascularized infarct tissue from normal, ischemic and infarct tissues, and wherein image data of the ROI are stored and/or displayed having values which are different for revascularized, normal, ischemic and infarct tissue.

17. An MRI method as in claim 11, wherein said tag-on data acquisition subsequences are effected alternately with said tag-off data acquisition sequences.

18. An MRI method as in claim 11, wherein said peak blood flow time for normal tissue has an earlier occurring peak flow time as compared to the peak blood flow time for ischemic tissue, and wherein distinguishing between normal and ischemic tissue is based on this temporal difference.

19. An MRI method as in claim 18, wherein said peak blood flow time for revascularized tissue has an earlier occurring peak flow time as compared to the peak blood flow time for normal tissue and/or ischemic tissue, and wherein revascularized tissue is identified based on this temporal difference.

20. An MRI method as in claim 11, wherein said relative peak blood flow value for normal tissue has a relatively higher peak value as compared to the peak blood flow value for ischemic tissue, and wherein distinguishing between normal and ischemic tissue is based on this difference in relative magnitude.