MagniXene™ pulmonary gas exchange to blood

The primary function of lungs is to offer a large surface area for gas exchange to blood. This requires three steps: First, adequate ventilation, gases must be transported from outside to the alveoli. Second, gas must diffuse adequately through the septal wall and into the capillary bed. Third, blood flow through the capillary bed must be sufficient to provide oxygen to the rest of the body. The essential components of this sequence can be investigated individually with many of the protocols discussed in these pages, or all in concert by measuring MagniXene™ in the pulmonary red blood cells.

MagniXene™ is highly soluble in blood and tissues, and provides a chemical shift in its resonance frequency that is characteristic of its chemical environment. Red blood cells, in particular, offer a resonance frequency that is well separated from those of other tissue compartments. Consequently the amount of MagniXene™ present in contact with red blood cells and the timing of the growth of that amount can offer regional information on pulmonary health.

The signal in red blood cells may, however, be too small to image directly. We will investigate and indirect method call Xenon magnetization Transfer Contrast (XTC). Rather than measure the signal of xenon in blood directly, we destroy it over and over again. If a large quantity of xenon is being transferred to the blood, the overall signal in that region will drop more rapidly than in regions where little xenon is being transferred to blood. The difference between the images taken before and after these repeated depolarizations represents how much xenon is being exchanged with the bloodstream.