Comparison of CPMG and Uhrig Dynamic Decoupling (UDD) for tissue refocusing in MRI

TL;DR

This study compares the effectiveness of CPMG and UDD dynamic decoupling sequences in MRI tissue refocusing, finding CPMG generally performs better due to noise characteristics and susceptibility to systematic errors.

Contribution

The paper provides an experimental comparison of CPMG and UDD sequences in MRI, highlighting CPMG's superior performance and analyzing the reasons behind it.

Findings

CPMG offers better decoupling than UDD in MRI.

Noise spectra favor CPMG for tissue refocusing.

UDD is more sensitive to systematic errors.

Abstract

Two different dynamic decoupling strategies, the classic CPMG and the more recently proposed UDD protocol are compared in the context of magnetic resonance imaging (MRI). Both sequences were implemented on a 3T human MRI system and relaxometry was performed for a variety of tissue-mimicking agar and agarose gels. We find that CPMG provides moderately better decoupling than \UDD. The results are consistent with experimental noise spectra obtained from \textit{in vivo} spectroscopy results, which suggest that the type of noise spectra obtained would favor \CPMG. Theoretical coherence pathway analysis further suggests that \UDD\ is more susceptible to systematic errors due to static magnetic and radio-frequency field inhomogeneity or imperfect excitation and refocusing pulse profiles.