Changes in alveolar septal thicknesses in ILD

Interstitial lung disease (ILD) leads to a thickening in the interstitium in the alveolar septal walls. This increase in thickness can frustrate gas exchange to the blood and limit the oxygen saturation of blood, especially during exercise. ILD often afflicts patients without any known cause.

The solubility of MagniXene™ in tissues can be exploited to measure septal wall thicknesses. As noted above, the lung regions with inhaled MagniXene™ offer two frequency peaks: a gas peak which calibrates the volume under consideration, and a dissolved peak which measures MagniXene™ in tissues. The depth of penetration of the xenon saturating the tissues can be controlled by the timing. We first quench all the signal-producing xenon magnetization dissolved in the tissues, then measure how much has diffused back into the tissues. We perform this measurement at several points in time: the signal strength present after a short time corresponds to a layer of xenon permeating only a thin region of the tissue surface, while measurements recorded after longer times represent a more complete saturation of xenon throughout the septal tissue volume. If we then divide the volume of tissues, represented by a measurement of the amount of saturated xenon at long times, by the surface area, represented by the xenon signal at short times, we obtain the septal wall thickness.

We performed this measurement on three subjects known to be suffering with mild to moderate ILD, registering significantly higher measures of septal wall thickness on the two subjects at a more advanced stage of disease.