title: MPnRAGE: A technique to simultaneously acquire hundreds of differently contrasted MPRAGE images with applications to quantitative T1 mapping.
abstract: OBJECTIVE
  To introduce a new technique called MPnRAGE, which produces hundreds of images with different T1 contrasts and a B1 corrected T1 map.
  
  
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Waisman Center and Department of Radiology, University of Wisconsin-Madison, Madison, Wisconsin, USA.
authors.forename: Steven
authors.initials: S
authors.lastname: Kecskemeti
authors.affiliation: Department of Radiology, University of Wisconsin-Madison, Madison, Wisconsin, USA.
authors.forename: Alexey
authors.initials: A
authors.lastname: Samsonov
authors.affiliation: Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin, USA.
authors.forename: Samuel A
authors.initials: SA
authors.lastname: Hurley
authors.affiliation: Waisman Center, University of Wisconsin-Madison, Madison, Wisconsin, USA.
authors.forename: Douglas C
authors.initials: DC
authors.lastname: Dean
authors.affiliation: Department of Radiology and Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, Wisconsin, USA.
authors.forename: Aaron
authors.initials: A
authors.lastname: Field
authors.affiliation: Waisman Center, Department of Medical Physics and Department of Psychiatry, University of Wisconsin-Madison, Madison, Wisconsin, USA.
authors.forename: Andrew L
authors.initials: AL
authors.lastname: Alexander
mesh_terms: D000328:Adult; D001921:Brain / Q000033:anatomy & histology / Q000502:physiology; D001931:Brain Mapping / Q000379:methods*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D019047:Phantoms, Imaging
keywords: Look-Locker; MPRAGE; T1 mapping; T1 weighted imaging; inversion recovery; segmentation