[Niobium powder--a new x-ray contrast medium for tracheobronchography].

In inhalation tracheobronchography with niobium powder in rabbits and a volunteer (physician), excellent contour bronchograms with detailed imaging of the structure of the mucosa were obtained. With methodically proper application the niobium particles of 20-40 microns do not penetrate into the alveoli and are quickly (within 1-5 days) eliminated from the bronchi. Investigations with mice have shown, that niobium powder is insoluble, does not irritate tissues and is not resorbed. It is also nontoxic.