Die Bedeutung bildgebender Diagnostik und interventioneller Therapie bei Erkrankungen der ableitenden Tränenwege

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

BACKGROUND

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.

MATERIALS AND METHODS

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.

RESULTS

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.

CONCLUSION

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.

Cone-Beam Computed Tomography (CBCT) dacryocystography for imaging of the nasolacrimal duct system

PURPOSE

To evaluate the usefulness and safety of cone-beam computed tomography (CBCT) dacryocystography in detecting lesions, identifying coexisting soft-tissue changes and determining treatment options in patients with epiphora.

PATIENTS AND METHODS

Unilateral digital subtraction dacryocystography and CBCT dacryocystography were carried out on 45 patients. Stenoses and occlusions were identified and coexisting changes such as septal deviation and dacryoliths were noted. The diameter of the bony lacrimal duct of affected and unaffected side was measured and related to the clinically evident epiphora. An attempt was made to base the subsequent therapeutic planning on the CBCT dacryocystographic findings. Additionally, the radiation dose levels for CBCT dacryocystography in comparison to those of multislice computed tomography (MSCT) were evaluated in a standardized head-neck Rando-Alderson phantom.

RESULTS

Nasolacrimal duct obstructions were present in 37/45 patients, 18 with a stenosis and 19 with an occlusion in parts of the lacrimal outflow system. The minimal bony diameter of the side with epiphora was significantly decreased compared to the unaffected side. Coexisting soft-tissue changes did not correlate significantly with the clinical sign of epiphora. Eight patients showed no underlying reason for the epiphora and were treated conservatively. A total of eleven patients received interventional therapy for their stenosis and 23 patients had to be treated surgically. A further three patients received medical treatment for infection, before surgery and interventional therapy, respectively, were carried out. Dose levels for CBCT imaging remained far below those of MSCT.

CONCLUSION

CBCT dacryocystography is a safe and time-efficient modality for assessing the nasolacrimal duct system in patients with epiphora. CBCT dacryocystography provides detailed images of the nasolacrimal drainage system, surrounding soft tissue, and bony structures in one diagnostic tour. It allows clear measurement of the bony nasolacrimal duct and displays information beyond that of the drainage lumen, improving the planning of therapeutic interventional and surgical procedures.