TY - JOUR
T1 - MR chemical exchange imaging with spin-lock technique (CESL)
T2 - A theoretical analysis of the Z-spectrum using a two-pool R1 relaxation model beyond the fast-exchange limit
AU - Yuan, Jing
AU - Zhou, Jinyuan
AU - Ahuja, Anil T.
AU - Wang, Yi Xiang J.
PY - 2012/12/21
Y1 - 2012/12/21
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=84870322280&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84870322280&partnerID=8YFLogxK
U2 - 10.1088/0031-9155/57/24/8185
DO - 10.1088/0031-9155/57/24/8185
M3 - Article
C2 - 23175033
AN - SCOPUS:84870322280
SN - 0031-9155
VL - 57
SP - 8185
EP - 8200
JO - Physics in medicine and biology
JF - Physics in medicine and biology
IS - 24
ER -