Dynamic assessment of paranasal sinus ventilation using xenon-enhanced computed tomography.

Disease of the paranasal sinuses is a common and costly condition. Evaluation of the efficacy of either medical or surgical methods of treatment is limited by the lack of quantitative methods to characterize sinus ventilation, which may be an important determinant of the baseline physiological state of the sinuses. Xenon-enhanced computed tomography (Xe-CT) measurement of sinus ventilation provides a noninvasive method of quantifying maxillary sinus ventilation using the nonradioactive, radiodense gas Xe as a tracer. Study subjects breathed a mixture of Xe gas and oxygen through a close-fitting nasal mask during serial CT imaging of a single radiographic plane through the maxillary sinuses--a generally well-tolerated protocol. Analysis of the sinus density-time curves allowed calculation of first-order exponential time constants from which specific ventilation rates could be determined for individual sinuses. Previously developed data analysis techniques were used to assess the statistical significance of the data and determine confidence intervals, allowing examination of the effects of noise in the data, and to demonstrate areas for further study protocol refinement. We conclude that Xe-CT measurement of sinus ventilation is a potentially valuable noninvasive technique for the diagnostic imaging of the human maxillary sinus.