Samira Kazan1, Steven Reynolds2, Tooba Alizadeh1, Adriana Bucur2, Aneurin Kennerley3, Vincent Cunningham4, Martyn Paley2, Gillian M. Tozer1
1CR-UK/YCR Sheffield Cancer Research Centre, University of Sheffield, Sheffield, South Yorkshire, United Kingdom; 2Academic Unit of Radiology, University of Sheffield, Sheffield, South Yorkshire, United Kingdom; 3Signal Processing in Neuroimaging and Systems Neuroscience, University of Sheffield, Sheffield, South Yorkshire, United Kingdom; 4Aberdeen Biomedical Imaging Centre, University of Aberdeen, Aberdeen, Scotland, United Kingdom
Mathematical models are required to estimate kinetic parameters of [1-13C] pyruvate-lactate interconversion from magnetic resonance spectroscopy data. It has been shown previously that the use of a measured arterial input function provides a robust and more comprehensive analysis of the kinetics compared to using a hypothetical box-car input function. A measured AIF reduces the number of free parameters for fitting and provides physiologically meaningful values not only for the rate constant of conversion of pyruvate to lactate, but also for clearance of pyruvate from the blood to the tissue. This parameter would be of particular relevance if blood flow effects were of interest in a study. Urea has been used previously as a perfusion marker to track the perfusion of pyruvate to the site of interest. In this study, by simultaneous injection of hyperpolarized 13C pyruvate and urea we measured both AIFs in order to compare the clearance/perfusion rates obtained using both methods at a tumor site.