Powdered diatrizoic acid for radiography of the respiratory tract.  Part I. Experimental investigation. 
Powdered diatrizoic acid as a contrast medium administered by inhalation and insufflation for visualization of the airways was tested in vitro and in 21 dogs.  Good radiopacity of the contrast medium and its antibacterial activity was found in vitro.  In the majority of animal experiments visualization of the bronchial tree down to segmental and partially to subsegmental bronchi with only minimal agglomeration of contrast medium and with good or very good demonstration of anatomic details was achieved.  In the majority of dogs contrast medium was eliminated from the lungs within 18 hours.  Arterial blood gases tested on 5 dogs showed only unimportant changes after contrast medium administration.  No adverse reactions were observed.  Histologic and ultrastructural examinations after contrast studies showed phagocytic reaction to diatrizoic acid, transient impairment of production of surfactant, reactive changes of bronchial mucosa, and no fibrotic changes in the long-term observation.