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Abstract #0039

Eu3+-Based PARACEST Agents with Intermediate Water Exchange Rates Also Act as T2 Exchange (T2exch) Contrast Agents

Todd C. Soesbe1, Federico A. Rojas-Quijano1, Matthew E. Merritt1, A. Dean Sherry1,2

1Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, United States; 2Department of Chemistry, The University of Texas at Dallas, Dallas, TX, United States

In our initial in vivo murine studies of CEST agents, we observed a significant loss of MR signal in certain tissue types, most notably the kidneys (intravenous injection) and human cancer cell xenografts (intratumoral injection). This loss in signal was present even when the CEST saturation pulse was omitted from the imaging sequence, and appeared to be caused by a local decrease in T2 due to the presence of the CEST agent. We hypothesized that the proton exchange that enables the CEST effect can also cause a decrease in T2 for compounds with intermediate proton exchange rates.