MR chemical exchange imaging with spin-lock technique (CESL): A theoretical analysis of the Z-spectrum using a two-pool R1 relaxation model beyond the fast-exchange limit

Jing Yuan, Jinyuan Zhou, Anil T. Ahuja, Yi Xiang J. Wang

Research output: Contribution to journalArticle

Abstract

The chemical exchange (CE) process has been exploited as a novel and powerful contrast mechanism for MRI, which is primarily performed in the form of chemical exchange saturation transfer (CEST) imaging. A spin-lock (SL) technique can also be used for CE studies, although traditionally performed and interpreted quite differently from CEST. Chemical exchange imaging with spin-lock technique (CESL), theoretically based on the Bloch-McConnell equations common to CEST, has the potential to be used as an alternative to CEST and to better characterize CE processes from slow and intermediate to fast proton exchange rates through the tuning of spin-lock pulse parameters. In this study, the Z-spectrum and asymmetric magnetization transfer ratio (MTRasym) obtained by CESL are theoretically analyzed and numerically simulated using a general two-pool R1 relaxation model beyond the fast-exchange limit. The influences of spin-lock parameters, static magnetic field strength B0 and physiological properties on the Z-spectrum and MTRasym are quantitatively revealed. Optimization of spin-lock frequency and spin-lock duration for the maximum CESL contrast enhancement is also investigated. Numerical simulation results in this study are compatible with the findings in the existing literature on CE imaging studies.

Original languageEnglish (US)
Pages (from-to)8185-8200
Number of pages16
JournalPhysics in medicine and biology
Volume57
Issue number24
DOIs
StatePublished - Dec 21 2012

ASJC Scopus subject areas

  • Radiological and Ultrasound Technology
  • Radiology Nuclear Medicine and imaging

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