Abstract #3379

Imaging ParaCEST Agents Using Frequency Labeled Exchange Transfer (FLEX) MRI

Chien-Yuan Lin¹,², Nirbhay N. Yadav²,³, S. James Ratnakar¹, A. Dean Sherry¹,⁴, Peter C. M. van Zijl²,³

¹Advanced Imaging Resarch Center, University of Texas Southwestern Medical Center, Dallas, TX, United States; ²F.M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, United States; ³Division of MR Research, Russell H. Morgan Dept. of Radiology and Radiological Science, Johns Hopkins University, Baltimore, MD, United States; ⁴University of Texas at Dallas, Dallas, TX, United States

Frequency labeled exchange transfer (FLEX) MRI is a pulse sequence that uses excitation instead of saturation to detect chemical exchange saturation transfer (CEST) agents. It has previously been shown to allow detection of rapidly exchanging water groups on paramagnetic (paraCEST) agents as well as separation of magnetization transfer (MT) effects from exchange effects using time domain analysis. In the present study, we implemented the FLEX method on a preclinical MRI system and show that FLEX imaging of paraCEST agents is possible. This should have potential for imaging the paraCEST agents in vivo where MT effects often obscure such agents due to the need for using high B1 for rapidly exchanging groups.