title: Algorithm for fast monoexponential fitting based on Auto-Regression on Linear Operations (ARLO) of data.
abstract: OBJECTIVE
  To develop a fast and accurate monoexponential fitting algorithm based on Auto-Regression on Linear Operations (ARLO) of data, and to validate its accuracy and computational speed by comparing it with the conventional Levenberg-Marquardt (LM) and Log-Linear (LL) algorithms.
  
  
  METHODS
  ARLO, LM, and LL performances for T2* mapping were evaluated in simulation and in vivo imaging of liver (n=15) and myocardial (n=1) iron overload patients and the brain (two healthy volunteers).
  
  
  RESULTS
  In simulations, ARLO consistently delivered accuracy similar to LM and significantly superior to LL. In in vivo mapping of T2 * values, ARLO showed excellent agreement with LM, while LL showed only limited agreements with ARLO and LM. Compared with LM and LL in the liver, ARLO was 125 and 8 times faster using our Matlab implementations, and 156 and 13 times faster using our C++ implementations. In C++ implementations, ARLO reduced the online whole-brain processing time from 9 min 15 s of LM and 35 s of LL to 2.7 s, providing T2 * maps approximately in real time.
  
  
  CONCLUSIONS
  Due to comparable accuracy and significantly higher speed, ARLO can be considered as a valid alternative to the conventional LM algorithm for online T2 * mapping.
authors.affiliation: Shanghai Key Laboratory of Magnetic Resonance and Department of Physics, East China Normal University, Shanghai, China; Yifu Inc, Jiaxing, Zhejiang Province, China.
authors.forename: Mengchao
authors.initials: M
authors.lastname: Pei
authors.forename: Thanh D
authors.initials: TD
authors.lastname: Nguyen
authors.forename: Nanda D
authors.initials: ND
authors.lastname: Thimmappa
authors.forename: Carlo
authors.initials: C
authors.lastname: Salustri
authors.forename: Fang
authors.initials: F
authors.lastname: Dong
authors.forename: Mitch A
authors.initials: MA
authors.lastname: Cooper
authors.forename: Jianqi
authors.initials: J
authors.lastname: Li
authors.forename: Martin R
authors.initials: MR
authors.lastname: Prince
authors.forename: Yi
authors.initials: Y
authors.lastname: Wang
mesh_terms: D000328:Adult; D000465:Algorithms; D001921:Brain / Q000473:pathology*; D003198:Computer Simulation; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D016014:Linear Models; D008297:Male; D009716:Numerical Analysis, Computer-Assisted; D012044:Regression Analysis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
keywords: Levenberg-Marquardt; Log-Linear; T2* mapping; autoregression; iron overload