Pouymayou, Bertrand; Buehler, Tania; Kreis, Roland; Boesch, Christoph Hans (2017). Test-retest analysis of multiple (31) P magnetization exchange pathways using asymmetric adiabatic inversion. Magnetic resonance in medicine, 78(1), pp. 33-39. Wiley-Liss 10.1002/mrm.26337
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PURPOSE
A (31) P-MR inversion transfer (IT) method with a short adiabatic inversion pulse is proposed and its test-retest reliability was evaluated for two spectral fitting strategies.
METHODS
Assessment in a test-retest design (3 Tesla, vastus muscles, 12 healthy volunteers, 14 inversion times, 22 ms asymmetric adiabatic inversion pulse, adiabatic excitation); spectral fitting in Fitting Tool for Interrelated Arrays of Datasets (FitAID) and Java Magnetic Resonance User Interface (jMRUI); least squares solution of the Bloch-McConnell-Solomon matrix formalism including all 14 measured time-points with equal weighting.
RESULTS
The cohort averages of k[PCr→γ-ATP] (phosphocreatine, PCr; adenosine triphosphate, ATP) are 0.246 ± 0.050s(-1) versus 0.254 ± 0.050s(-1) , and k[Pi→γ-ATP] 0.086 ± 0.033s(-1) versus 0.066 ± 0.034s(-1) (average ± standard deviation, jMRUI versus FitAID). Coefficients of variation of the differences between test and retest are lowest (9.5%) for k[PCr→γ-ATP] fitted in FitAID, larger (15.2%) for the fit in jMRUI, and considerably larger for k[Pi→γ-ATP] fitted in FitAID (43.4%) or jMRUI (47.9%). The beginning of the IT effect can be observed with magnetizations above 92% for noninverted lines while inversion of the ATP resonances is better than -72%.
CONCLUSION
The performance of the asymmetric adiabatic pulse allows an accurate observation of IT effects even in the early phase; the least squares fit of the Bloch-McConnell-Solomon matrix formalism is robust; and the type of spectral fitting can influence the results significantly. Magn Reson Med, 2016. © 2016 Wiley Periodicals, Inc.
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