Vipul R. Sheth1, Yuguo Li2, Liu
Qi Chen3, Christine A. Howison4, Mark D. Pagel5
1Biomedical Engineering,
Case Western Reserve University, Cleveland, OH, United States; 2Radiology,
Case Western Reserve University, Cleveland, OH, United States; 3Chemistry
& Biochemistry, University of Arizona, Tucson, AZ, United States; 4Arizona
Research Laboratories, University of Arizona, Tucson, AZ, United States; 5Biomedical
Engineering and Chemistry & Biochemistry, University of Arizona, Tucson,
AZ, United States
A PARACEST MRI contrast agent, Yb-DO3A-oAA, can measure pH over a range of 6-7.9 pH units, with a precision of 0.206 pH units and an accuracy of 0.089 pH units. This measurement is based on a ratio of the two CEST effects of the PARACEST agent, which is independent of the agent's concentration or the samples T1sat relaxation time. Combined with a CEST-FISP acquisition protocol, the PARACEST agent was used to measure the extracellular pH (pHe) within a subcutaneous tumor and muscle of a MDA-MB-231 breast cancer model.