Liu Qi Chen1, Vipul
R. Sheth2, Christine A. Howison3, Phillip H. Kuo4,
Mark D. Pagel5
1Chemistry
& Biochemistry, University of Arizona, Tucson, AZ, USA; 2Biomedical
Engineering, Case Western Reserve University, Cleveland, OH, USA; 3Arizona
Research Laboratories, University of Arizona, Tucson, AZ, USA; 4Radiology,
Medicine, Biomedical Engineering, University of Arizona, Tucson, AZ, USA; 5Biomedical
Engineering & Chemistry & Biochemistry, University of Arizona,
Tucson, AZ, USA
Ultravist, a contrast agent that is clinically approved for X-ray/CT imaging, can also serve as a DIAmagnetic CEST (DIACEST) MRI contrast agent. A ratio of the two CEST effects from Ultravist can be used to measure pH over a range of 6.2-7.4 pH units with a precision of 0.070 pH units. This ratiometric approach obviates the need to know the agent's concentration or sample's T1sat relaxation time when measuring pH. We have used this DIACEST agent and a CEST-FISP MRI method to measure the extracellular pH (pHe) within a subcutaneous tumor and muscle of a mouse model of PANC-1 pancreatic cancer.
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