Elena Vinogradov1, Todd C. Soesbe2, James A. Balschi3, Dean A. Sherry2,4, Robert E. Lenkinski1
1Department of Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA; 2Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, USA; 3NMR Laboratory for Physiological Chemistry, Brigham and Womens Hospital, Harvard Medical School, Boston, MA, USA; 4Department of Chemistry, University of Texas at Dallas, Dallas, TX, USA
Chemical Exchange Saturation Contrast utilizes selective presaturation of a small pool of exchanging protons and is manifested in the decrease of the free water signal. Thus, CEST contrast is negative and requires the detection of small signal changes on top of a strong background signal. Here we introduce a Positive CEST (PCEST) scheme that results in the increased signal intensity in the presence of the agent and RF. Similar to the original CEST, the contrast can be switched ON and OFF. The sequence leads to better utilization of the dynamic range and results in the substantial background suppression.