Zhongliang Zu1, Junzhong Xu1, Hua Li1, Christopher C. Quarles1, Mark D. Does1, John C. Gore1, Daniel F. Gochberg1
1Institue of Imaging Science, Vanderbilt University, Nashville, TN, United States
CEST Z-spectra show dips from exchangeable sites (-NH2, -NH, and OH) at down field frequencies and from Nuclear Overhauser Enhancement (NOE) at up field frequencies. Quantitative mapping of such effects is difficult as conventional asymmetric analyses include contributions from both exchangeable sites and NOE. Here, we use a modified CEST method, chemical exchange ration transfer (CERT), to quantify amide proton transfer (APT) and NOE through subtraction of CEST signals at two irradiation flip angles instead of two frequency offsets. In vivo experiments on a rat brain with 9L tumor show interesting contrasts from APT and NOE.