Two-Frequency Irradiation of the pH-Dependent Amide Proton Transfer Effect in a Clinical Scanner:simulation and Experiment

Chao Xu¹, Christian Labadie¹, Andr Pampel¹, Samer Salamekh¹, Harald E. Mller¹

Two-frequency radiofrequency (RF) irradiation was claimed to allow the isolation of the chemical exchange saturation (CEST) from magnetization transfer (MT) asymmetry. We implemented this technique for detecting pH-dependent APT effect in a clinical 3T MRI scanner and compared the experimental data acquired from egg white solutions with the simulation result using a three-pool model. According to our study, the double-frequency irradiation enables the partial correction of the MT asymmetry. A linear dependence between pH and measured MTRasym by the double-frequency pulse was observed in the cross-linked egg white solutions.