Purpose: To assess unenhanced magnetic resonance imaging (MRI) in the preoperative evaluation of obstructive epiphora in patients undergoing dacryocystorhinostomy (DCR) and in particular, to evaluate the efficacy of this technique in the detection of the exact level of obstruction occurring in the naso-lachrymal duct (NLD). The correct identification and characterization of the NLD and its obstructions lead to a more effective surgery, preventing recurrent dacryocystitis after the surgical treatment.
Methods: From January 2009 to December 2014, 127 obstructive epiphoras were diagnosed and treated in 127 patients (35 M, 92 F; mean age 60.7 ± 7.48 years, range 42-75 years) with endoscopic DCR, in a IRB-approved protocol. To precisely define the morphology of the NLD and the site of obstruction, some of these patients (67/127) underwent unenhanced 1.5-T MR with TrueFISP and VIBE sequences, while the remaining (60/127) underwent Gadolinium-enhanced 1.5-T MR. Afterwards, surgery checked the real site of obstruction in both groups of patients (enhanced and unenhanced MR), with surgical outcomes matched with previous MR reports.
Results: In all cases, unenhanced MRI was able to detect the exact site of obstruction along the NLD, allowing a correct planning of surgical endoscopic procedures. On the contrary, enhanced MRI wrongly diagnosed six patients with proximal stenosis (6/60, 10.0%) as intermediate NLD obstruction. Unenhanced MRI was found to be more accurate than enhanced MRI with a statistical significant difference (p value = 0.0256) and obviously cheaper and easier to perform. All imaging reports were verified with surgery. The correct identification of the level of obstruction allowed successful surgery in around 73% (93/127) of patients, who had no recurrence during 6-month follow-up.
Conclusion: In patients with epiphora, unenhanced MR showed to be highly reliable and even more effective than enhanced MR in the preoperative characterization of NLD stenosis, with no need of performing complex, time-wasting and expensive procedures for the administration of topical contrast media.
Keywords: Dacryocystorhinostomy; Epiphora; Magnetic resonance imaging; Naso-lachrymal duct.