title: Simple recipe for accurate T(2) quantification with multi spin-echo acquisitions.
abstract: OBJECTIVE
  The quantification of magnetic resonance relaxation parameters T 1 and T 2 have the potential for improved disease detection and classification over standard clinical weighted imaging. Performing a mono-exponential fit on multi spin-echo (MSE) data provides quantitative T 2 values in a clinically acceptable scan-time. However, due to technical imperfections of refocusing pulses, stimulated echo contributions to the signals lead to significant deviations in the resulting T 2 values. In this work, a simple auto-calibrating correction procedure is presented, allowing the accurate estimation of T 2 from MSE acquisitions.
  
  
  METHODS
  Correction factors for T 2 values obtained from MSE acquisitions with a mono-exponential fit are derived from simulations following the extended phase graph formulation. A closed formula is given for the calculation of the required correction factors directly from the measured data itself.
  
  
  RESULTS
  Simulations and phantom experiments show high accuracy of corrected T 2 values for a wide range of clinically relevant T 2 values and for different nominal refocusing flip angles. In addition, corrected T 2 maps of the human brain are presented.
  
  
  CONCLUSIONS
  A simple recipe is provided to correct T 2 values obtained from MSE acquisitions via a mono-exponential fit for the influence of stimulated echoes. Since all required parameters are extracted from the data themselves, no additional acquisitions are required.
authors.affiliation: Research Center Magnetic Resonance Bavaria (MRB), Am Hubland, 97074, Würzburg, Germany, dneumann@physik.uni-wuerzburg.de.
authors.forename: Daniel
authors.initials: D
authors.lastname: Neumann
authors.forename: Martin
authors.initials: M
authors.lastname: Blaimer
authors.forename: Peter M
authors.initials: PM
authors.lastname: Jakob
authors.forename: Felix A
authors.initials: FA
authors.lastname: Breuer
mesh_terms: D000465:Algorithms; D016477:Artifacts; D001921:Brain / Q000033:anatomy & histology*; D017352:Echo-Planar Imaging / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D009716:Numerical Analysis, Computer-Assisted; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted