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Real‐time quantification of T 2 * changes using multiecho planar imaging and numerical methods
Author(s) -
Hagberg G.E.,
Indovina I.,
Sanes J.N.,
Posse S.
Publication year - 2002
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.10283
Subject(s) - linear regression , nonlinear system , regression , computer science , nonlinear regression , regression analysis , mathematics , artificial intelligence , algorithm , pattern recognition (psychology) , statistics , physics , quantum mechanics
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. Magn Reson Med 48:877–882, 2002. © 2002 Wiley‐Liss, Inc.