Albert P. Chen1, Ralph E. Hurd2,
Marie A. Schroeder3,4, Angus Z. Lau4,5, Yi-Ping Gu4,
Wilfred W. Lam4, Charles H. Cunningham4,5
1GE Healthcare, Toronto,
ON, Canada; 2GE Healthcare, Menlo Park, CA, United States; 3Department
of Physiology, Anatomy & Genetics, University of Oxford, Oxford, United
Kingdom; 4Imaging Research, Sunnybrook Health Sciences Centre,
Toronto, ON, Canada; 5Deptartment of Medical Biophysics,
University of Toronto, Toronto, ON, Canada
To improve the robustness of pH measurement using hyperpolarized H13CO3- and 13CO2 signals in presence of carbonic anhydrase activity, the 13CO2 resonance was excited independently with a chemically selective RF pulse of larger tip-angle (to achieve higher SNR), while the other resonances of interest were acquired with a smaller tip angle. Accurate pH measurement could still be obtained even with repeated tipping (for temporally and/or spatially resolved data), since the ratio between the two pools was rapidly restored by the enzyme mediated exchange. This method was demonstrated in phantom and in vivo in pig heart.
Keywords