133Xenon washout in the paranasal sinuses--a diagnostic tool for assessing ostial function.

A 133Xenon washout test is presented and interpreted. It was developed on the basis of studies into the accumulation of aerosols of different makes (lithium chloride in the form of ultrasonic, vibratory and pressurized aerosols) in the paranasal sinuses and sequential scintigraphy with radioactively labeled aerosols (99m Technetium colloidal sulfur) and is designed to shed light on the gas exchange in the paranasal sinuses and the patency of their orifices. The test constitutes a valuable addition to the battery of diagnostic tools for assessing paranasal sinus function and, at the same time, documents the true value of aerosol therapy.