PHASE SENSITIVE T1 MAPPING IN MAGNETIC RESONANCE IMAGING

• US 20130272591A1
• Filed: 04/17/2013
• Published: 10/17/2013
• Est. Priority Date: 04/17/2012
• Status: Active Grant

• Current Assignee: Siemens Healthineers AG (Siemens AG), The United States of America As Represented By The Secretary of Agriculture
• Original Assignee: National Institutes of Health (NIH) (Government of the United States of America), Siemens AG, Siemens Corp. (Siemens AG)
• Inventors: Xue, Hui, Kellman, Peter, Greiser, Andreas
• Granted Patent: US 9,129,424 B2
• Time in Patent Office: Days
• US Class Current: 382/131
• 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 33/56509 due to motion, displacement or flow, e.g. gradient moment nulling G01R33/567 takes precedence
• CPC Class Codes: G06T 11/003 Reconstruction from projections, e.g. tomography

Abstract

Phase sensitive T1 mapping is provided in magnetic resonance (MR). The phase from samples of a modified Look-Locker inversion recovery sequence may be used to normalize contrast, allowing for accurate motion registration without extra information acquisition. The sign may be estimated, allowing T1 mapping with a single application of a non-linear fit.

Claims

1. A method for magnetic resonance (MR) T1 mapping with motion correction and parametric fitting, the method comprising:

acquiring, with an MR scanner, first frames of data in a first sampling series during a first inversion recovery;

acquiring, with the MR scanner, second frames of data in a second sampling series during a second inversion recovery;

determining, with a processor, motion between a longest inversion time one of the first frames and a longest inversion time one the second frames;

motion correcting, with the processor, the first frames as a function of the motion;

changing, with the processor, phase of the motion corrected first frames of data and of the second frames of data, an amount of the changing being by a phase of a longest of the longest inversion time ones of the first and second frames;

calculating, with the processor, polarities for the first and second frames as a first sign of a real part after changing the phase;

multiplying, with the processor, a magnitude of the first and second frames by the respective polarity;

registering, with the processor, the first and second frames using results from the multiplying;

deforming, with the processor, at least some of the first and second frames as a function of the registering;

estimating, with the processor, a second sign for each of the deformed first and second frames; and

computing, with the processor, a T1 map as a function of the second signs.

2. The method of claim 1 wherein acquiring the first and second frames comprises acquiring the first and second frames as complex signals reconstructed from k-space information during a breath hold of a patient, the first frames acquired at a first phase of a first plurality of heart cycles and the second frames acquired at a second phase of a second plurality of heart cycles, the first plurality of heart cycles separated by the second plurality of heart cycles by at least two heart cycles.

3. The method of claim 1 wherein determining the motion comprises non-rigid registering, and wherein motion correcting comprises applying a deformation field of the non-rigid registering.

4. The method of claim 1 wherein changing the phase comprises removing background phase, the background phase being the phase of the longest of the longest inversion time ones of the first and second frames.

5. The method of claim 1 wherein calculating the polarities comprises determining a positive or negative designation for an inversion time of each first frame and each second frame.

6. The method of claim 1 wherein the first and second frames each represent multiple locations in a planar region, wherein changing the phase comprises changing the phase on a location-by-location basis, wherein multiplying the magnitude comprises multiplying the magnitude on the location-by-location basis, and wherein computing the T1 map comprises computing T1 on the location-by-location basis.

7. The method of claim 1 wherein registering comprises performing a fast variational non-rigid registration with a localized cross-correlation cost function.

8. The method of claim 1 wherein estimating the second sign and calculating the polarities comprise determining relative to a zero of the first and second inversion recoveries.

9. The method of claim 1 wherein computing the T1 map comprises performing a non-linear least square fit for each location across the first frames.

10. The method of claim 9 wherein the non-linear least square fit is performed only once for each location across the first frames.

11. The method of claim 1 further comprising:

displaying the T1 map as an image.

12. In a non-transitory computer readable storage medium having stored therein data representing instructions executable by a programmed processor for phase sensitive T1 mapping in magnetic resonance (MR), the storage medium comprising instructions for:

scanning with a modified Look-Locker inversion recovery sequence;

recovering signs at different inversion recovery times of samples from the scanning, the signs being recovered as a function of phase; and

mapping T1 as a function of the signs.

13. The non-transitory computer readable storage medium of claim 12 wherein scanning comprises acquiring data representing locations of a plane at sample times corresponding to a phase of a heart cycle in response to an inversion recovery.

14. The non-transitory computer readable storage medium of claim 12 wherein recovering the signs comprises removing background phase of the samples and estimating the signs of a real part of the samples after the removing of the background phase.

15. The non-transitory computer readable storage medium of claim 12 wherein the scanning is repeated;

further comprising;

first motion correcting between samples of the scanning and the scanning repetition associated with a longest inversion recovery time prior to recovering the signs;

multiplying magnitudes of the samples with the signs; and

second motion correcting between the magnitudes multiplied with the signs of the scanning and the scanning repetition for all of the inversion recovery times.

16. The non-transitory computer readable storage medium of claim 12 wherein recovering comprises recovering as a function of the phase from one of the samples where the one of the samples is also used for the mapping.

17. The non-transitory computer readable storage medium of claim 12 wherein mapping T1 comprises performing a non-linear least square fit only once for a spatial location associated with an inversion recovery due to the recovering.

18. A system for phase sensitive T1 mapping in magnetic resonance (MR), the system comprising:

a magnetic resonance (MR) scanner configured to transmit a sequence of inversion pulses and scan a patient at multiple inversion times after each of the inversion pulses, the multiple inversion times triggered based on a heart cycle; and

a processor configured to remove background phase from signals at each of the inversion times based on phase of signals at the longest inversion time, to estimate a polarity of signals at each of the inversion times from the signals after removal of the background phase, to motion correct the signals across the inversion times as a function of the polarity, and to map T1 from the motion corrected signals.

19. The system of claim 18 wherein the MR scanner is configured to perform a modified Look-Locker inversion recovery sequence for each of the transmits and the scans.

20. The system of claim 18 wherein the processor is configured to re-estimate the polarities from the motion corrected signals and to map the T1 with a single non-linear least square fit to the motion corrected signals based on the re-estimated polarities.