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Magn Reson Med. 2016 Mar;75(3):1040-53. doi: 10.1002/mrm.25674. Epub 2015 Apr 17.

MPnRAGE: A technique to simultaneously acquire hundreds of differently contrasted MPRAGE images with applications to quantitative T1 mapping.

Author information

  • 1Waisman Center and Department of Radiology, University of Wisconsin-Madison, Madison, Wisconsin, USA.
  • 2Department of Radiology, University of Wisconsin-Madison, Madison, Wisconsin, USA.
  • 3Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin, USA.
  • 4Waisman Center, University of Wisconsin-Madison, Madison, Wisconsin, USA.
  • 5Department of Radiology and Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, Wisconsin, USA.
  • 6Waisman Center, Department of Medical Physics and Department of Psychiatry, University of Wisconsin-Madison, Madison, Wisconsin, USA.

Abstract

PURPOSE:

To introduce a new technique called MPnRAGE, which produces hundreds of images with different T1 contrasts and a B1 corrected T1 map.

THEORY AND METHODS:

An interleaved three-dimensional radial k-space trajectory with a sliding window reconstruction is used in conjunction with magnetization preparation pulses. This work modifies the SNAPSHOT-FLASH T1 fitting equations for radial imaging with view-sharing and develops a new rapid B1 correction procedure. MPnRAGE is demonstrated in phantoms and volunteers, including two volunteers with eight scans each and eight volunteers with two scans each. T1 values from MPnRAGE were compared with those from fast spin echo inversion recovery (FSE-IR) in phantoms and a healthy human brain at 3 Tesla (T).

RESULTS:

The T1 fit for human white and gray matter was T1MPnRAGE = 1.00 · T1FSE-IR + 24 ms, r(2) = 0.990. Voxel-wise coefficient of variation in T1 measurements across eight time points was between 0.02 and 0.08. Region of interest-based T1 values were reproducible to within 2% and agree well with literature values.

CONCLUSION:

In the same amount of time as a traditional MPRAGE exam (7.5 min), MPnRAGE was shown to produce hundreds of images with alternate T1 contrasts as well as an accurate and reproducible T1 map that is robust to B1 errors.

KEYWORDS:

Look-Locker; MPRAGE; T1 mapping; T1 weighted imaging; inversion recovery; segmentation

PMID:
25885265
PMCID:
PMC4609219
[Available on 2017-03-01]
DOI:
10.1002/mrm.25674
[PubMed - indexed for MEDLINE]
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