Marcus John Couch1,2, Alexei V. Ouriadov1, Giles E. Santyr1,3
1Imaging Research Laboratories, Robarts Research Institute, The University of Western Ontario, London, ON, Canada; 2Department of Physics & Astronomy, the University of Western Ontario, London, ON, Canada; 3Department of Medical Biophysics, The University of Western Ontario, London, ON, Canada
In this work, hyperpolarized 3He and 129Xe MRI was used to measure regional ventilation in the normal rat lung using the dynamic gas signal from inside the lungs. This method used a variable flip angle approach (FAVOR) to mitigate the effects of RF pulses and relaxation both in the ventilator system and in the rat lung. A theoretical model was used to fit signal enhancement curves on a pixel-by-pixel basis to generate two-dimensional maps of the ventilation parameter, r, which was defined as the fractional refreshment of gas per breath. Ventilation gradients were calculated in the superior/inferior and anterior/posterior directions.