Real-time quantification of T*2 changes using multiecho planar imaging and numerical methods

G. E. Hagberg, I. Indovina, J. N. Sanes, S. Posse

Research output: Contribution to journalArticlepeer-review


Conventional approaches to quantify whole brain T*2 maps use nonlinear regression with intensive computational requirements that therefore likely limit quantitative T*2 mapping for real-time applications. To overcome these limitations an alternative method, NumART*2 (NUMerical Algorithm for Real-time T*2 mapping) that directly calculates T*2 by a linear combination of images obtained at three or more different echo times was developed. NumART*2, linear least-squares, and nonlinear regression techniques were applied to multiecho planar images of the human brain and to simulated data. Although NumART*2 may overestimate T*2, it yields comparable values to regression techniques in cortical and subcortical areas, with only moderate deviations for echo spacings between 18 and 40 ms. NumART*2, like linear regression, requires 2% of the computational time needed for nonlinear regression and compares favorably with linear regression due to its higher precision. The use of NumART*2 for continuous on-line T*2 mapping in real time fMRI studies is shown.

Original languageEnglish
Pages (from-to)877-882
Number of pages6
JournalMagnetic Resonance in Medicine
Issue number5
Publication statusPublished - Nov 1 2002


  • Functional MRI
  • Multiecho acquisition
  • Quantitative T*
  • Real-time

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging
  • Radiological and Ultrasound Technology


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