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.