Purpose: Digital subtraction dacryocystography (DS-DCG) is considered the "gold standard" in the assessment of the nasolacrimal duct system but fails to delineate the soft tissue structures that surround the lacrimal drainage apparatus. The goal of this study was to compare high resolution MR surface coil imaging with DS-DCG to determine the value of gadolinium-enhanced MR dacryocystography (MR-DCG) in patients with epiphora.
Method: We performed bilateral MR-DCG and unilateral DS-DCG in 11 patients (aged 3-70 years) with epiphora using Gd-DTPA-containing eyedrops (Magnevist; 78.63 mg of Gd/ml diluted in a sterile 0.9% NaCl solution 1:100) and a water-soluble contrast medium (Omnipaque; 677 mg of Iohexol/ml). Radiographic and MR findings were separated and reviewed by two radiologists who were blinded to patients' names and histories. Afterwards, the passage of the contrast material was compared in the two procedures. The gold standard was defined as the distal-most point of the contrast material identified on either study.
Results: Obstruction of the nasolacrimal duct system was diagnosed with a sensitivity of 100% with both MR-DCG and DS-DCG. With MR-DCG, the two readers correctly diagnosed the location of an obstruction in 67 and 89% and with DS-DCG in 56 and 67%. With MR-DCG, contrast material was traced further distally than with DS-DCG in three patients. DS-DCG was superior in only one case in which MR-DCG failed to delineate fistulas distal to the nasolacrimal sac.
Conclusion: Our data suggest that MR-DCG is suitable for assessing drainage problems of the nasolacrimal duct system, giving additional information concerning the surrounding soft tissue structures. Further studies are required to show whether MR-DCG can replace DS-DCG as the gold standard in the assessment of the nasolacrimal duct system.