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Abstract #0400

In Vivo Detection of PI3K Pathway Inhibition by Hyperpolarized 13C MRSI at 14 Tesla

Myriam Marianne Chaumeil1, Subramanian Sukumar1, Humsa Venkatesh1, Christopher Ward1, Kristen R. Scott1, Tomoko Ozawa2, C David James2, John Kurhanewicz1, Daniel B. Vigneron1, Sarah J. Nelson1, Sabrina M. Ronen1

1Radiology, UCSF, San Francisco, CA, United States; 2Brain tumor Research Center, UCSF, San Francisco, CA, United States

In vivo inhibition of the PI3K pathway by Everolimus was evaluated using hyperpolarized (HP) 13C MRSI in subcutaneous tumors in mice at 14 Tesla. Whereas lactate-to-pyruvate ratio was increased in control animals, this ratio was decreased by 78% and 35% in treated animals relative to controls after 2 and 7 days, respectively. The drop in lactate-to-pyruvate ratio following Everolimus treatment is in line with the findings in treated cells and likely indicates a decrease in LDH activity in treated tumors. This preliminary in vivo study demonstrates the likely value of HP 13C studies of pyruvate for noninvasive monitoring PI3K inhibition.