[Low-dose helical CT-dacryocystography in nasolacrimal duct obstruction-a prospective study]

In addition to basic ophthalmologic diagnostic workup, different radiologic procedures can be performed for assessment of nasolacrimal duct obstruction. However, no gold standard imaging technique has yet been established. Using the results of the present study, the advantages of helical CT-dacryocystography (CT-DCG) are demonstrated, particularly when performed before endonasal endoscopic dacryocystorhinostomy.

In 21 patients with uni- or bilateral epiphora, 24 low-dose helical CT-DCGs were performed with non-ionic iodine-containing contrast medium and including three-dimensional reconstruction. For 8 patients, digital subtraction angiography (DSA)-DCG results were available for comparison with CT-DCG.

Using low-dose helical CT-DCG, either the location of nasolacrimal duct pathology could be exactly identified (n = 19; stenosis presaccal n = 3, intrasaccal n = 11, postsaccal n = 5) or nasolacrimal system block could be definitively excluded as the cause of epiphora (n = 5). For imaging of the perilacrimal and periorbital bony structures, CT-DCG is significantly better than DSA-DCG.

Low-dose helical CT-DCG with reconstruction of the coronal and sagittal planes represents an ideal imaging technique with low exposure for detection of nasolacrimal duct obstruction. By demonstrating all relevant anatomic landmarks for endoscopic dacryocystorhinostomy, helical CT-DCG enables head and neck surgeons to plan surgery optimally.