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Erschienen in:
01.12.2014 | Research Article
Simple recipe for accurate T 2 quantification with multi spin-echo acquisitions
Erschienen in: Magnetic Resonance Materials in Physics, Biology and Medicine | Ausgabe 6/2014
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Objective
The quantification of magnetic resonance relaxation parameters T
1 and T
2 have the potential for improved disease detection and classification over standard clinical weighted imaging. Performing a mono-exponential fit on multi spin-echo (MSE) data provides quantitative T
2 values in a clinically acceptable scan-time. However, due to technical imperfections of refocusing pulses, stimulated echo contributions to the signals lead to significant deviations in the resulting T
2 values. In this work, a simple auto-calibrating correction procedure is presented, allowing the accurate estimation of T
2 from MSE acquisitions.
Materials and methods
Correction factors for T
2 values obtained from MSE acquisitions with a mono-exponential fit are derived from simulations following the extended phase graph formulation. A closed formula is given for the calculation of the required correction factors directly from the measured data itself.
Results
Simulations and phantom experiments show high accuracy of corrected T
2 values for a wide range of clinically relevant T
2 values and for different nominal refocusing flip angles. In addition, corrected T
2 maps of the human brain are presented.
Conclusion
A simple recipe is provided to correct T
2 values obtained from MSE acquisitions via a mono-exponential fit for the influence of stimulated echoes. Since all required parameters are extracted from the data themselves, no additional acquisitions are required.