Chemical Exchange Mapping

Abstract Chemical exchange saturation transfer (CEST) imaging is an emerging MRI technique that provides a sensitive means for the detection of dilute labile proton groups via their exchange with the abundant bulk tissue water signal. CEST MRI has been applied to investigate biomolecules (e.g., creatine, glutamate, and amide protons) and microenvironment properties (e.g., pH and temperature), with increasing biomedical applications. Whereas CEST-weighted MRI is informative, the development of quantification CEST (qCEST) analysis allows the characterization of the underlying CEST system, including the labile proton concentration and the chemical exchange rate. Herein, we provide a comprehensive review of the principle of CEST MRI, its pulse sequence, experimental acquisition, and data analysis, in particular, the measurement of the labile proton exchange rate.