[Dacryocystography in the digital subtraction technic].

Dacryocystorhinostomy is well established as a common surgical approach to the treatment of obstructive epiphora. The importance of a radiological procedure for pre-operative diagnosis and postoperative follow-up is emphasised. Routine imaging (dacryocystography) of the nasolacrimal system is made difficult by the high contrast between bone and air in the sinuses and pharynx, by overlapping structures, and by the very small size of those structures that are of interest. Digital subtraction technique provides significantly improved visualisation even of poorly contrasted structures of the lacrimal system (i.e. canaliculi lacrimales), overcoming limitations imposed by inherently high object contrast. Representative case reports such as pre- and postsaccal stenosis and functional obstruction are presented. Digital subtraction dacryocystography is an important nonvascular application of digital imaging technology.