Craig K. Jones1, 2, Alan Huang1, 2, Jiadi Xu1, 2, Richard Anthony Edward Edden, 23, Michael Schr4, 5, Jun Hua1, 2, Nikita Oskolkov1, 2, Michael T. McMahon1, 2, Peter C.M. van Zijl1, 2
1Department of Radiology and Radiological Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, United States; 2FM Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, United States; 3Department of Radiology and Radiological Sciences, Johns Hopkins University, Baltimore, MD, United States; 4Philips Medical Systems, Highland Heights, OH, United States; 5Keller Center for Imaging Innovation, Barrow Neurological Institute, Phoenix, AZ, United States
CEST is a magnetization transfer (MT) technique to indirectly detect pools of exchangeable protons through the water signal. Low power RF pulses can slowly saturate protons with minimal interference of conventional semi-solid based MT contrast (MTC). When doing so saturation-transfer signals are revealed upfield from water in the CEST spectrum, which is in the frequency range of non-exchangeable aliphatic and olefinic protons. The visibility of such upfield signals indicates the presence of a transfer mechanism to the water signal, while their finite width indicates that these signals are likely due to mobile solutes.