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Optimized clinical T2 relaxometry with a standard CPMG sequence
Author(s) -
Pell Gaby S.,
Briellmann Regula S.,
Waites Anthony B.,
Abbott David F.,
Lewis David P.,
Jackson Graeme D.
Publication year - 2006
Publication title -
journal of magnetic resonance imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.563
H-Index - 160
eISSN - 1522-2586
pISSN - 1053-1807
DOI - 10.1002/jmri.20490
Subject(s) - relaxometry , accuracy and precision , imaging phantom , standard deviation , materials science , sequence (biology) , flip angle , nuclear magnetic resonance , spin echo , algorithm , computer science , physics , mathematics , chemistry , optics , magnetic resonance imaging , statistics , medicine , biochemistry , radiology
Purpose To optimize the accuracy and precision of T2 measurements using the standard Carr‐Purcell‐Meiboom‐Gill (CPMG) sequence. T2 values obtained with this technique are normally sensitive to imperfect refocusing due to the formation of unwanted stimulated echoes. Materials and Methods Modifications are made to the refocusing slice selection width and the interleaving scheme. A widened refocusing slice improves the uniformity of the refocusing flip angle across the slice. A slow spin echo acquisition provided “gold standard” T2 values. Repeated T2 measurements in phantom and human studies are used to compare the accuracy and precision of the optimized and non‐optimized CPMG implementations. Results The required slice thickness ratio between refocusing and excitation slice widths is found to be 3:1 for typical optimized radiofrequency pulses. T2 values obtained using this optimized implementation more closely correspond to “gold standard” values. Repeated T2 measurements indicate significantly improved correspondence between data and model. A reduction in the fitting error of approximately 70% is demonstrated for phantoms. Conclusion We demonstrate that a relatively simple change to the CPMG relaxometry sequence parameters from the default setup yields significant improvements in the accuracy and precision of T2 measurements. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.