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Abstract #0709

Detection of paraCEST Agents with Reduced MT Interference using Frequency Labeled Exchange Transfer (FLEX)

Chien-Yuan Lin1,2, Nirbhay N. Yadav2,3, Joshua I. Friedman4, S. James Ratnakar1, A. Dean Sherry1,5, Peter C. M. van Zijl2,3

1Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, USA; 2F. M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA; 3Division of MR Research, Russell H. Morgan Dept. of Radiology & Radiological Science, Johns Hopkins University, Baltimore, MD, USA; 4Pharmacology & Molecular Sciences, Johns Hopkins University, Baltimore, MD, USA; 5University of Texas at Dallas, Dallas, TX, USA

Paramagnetic chemical exchange saturation transfer (paraCEST) agents combine the benefit of a large chemical shift difference and a fast exchange rate for sensitive MRI detection. However, the in vivo detection of these agents is hampered by the need for high B1 fields to allow sufficiently fast saturation, causing interference of large magnetization transfer (MT) effects from semi-solid macromolecules. It is shown on phantoms that the use of frequency labeled exchange transfer (FLEX) allows detection of such rapidly exchanging agents and that interfering broad components such as MT effects can be removed using T2* filtering of the signal.