A Physiological, Non-Cannulated CT–Dacryocystography Protocol Using Dropwise Iodixanol Instillation: A Pilot Study

Background: Conventional CT–dacryocystography (CT-DCG) requires canalicular cannulation and forced contrast injection, which may distort anatomy and cause discomfort. This study describes a non-cannulated CT-DCG protocol using dropwise iodixanol 320 instillation designed to simulate physiological tear drainage. Methods: We retrospectively reviewed 80 patients (25 males, 55 females; mean age 64.3 ± 8.9 years) with suspected nasolacrimal duct obstruction. Iodixanol 320 was instilled at 2 drops/min for 10 min without cannulation. Imaging was performed on a low-dose 128-slice CT system with multiplanar reconstructions. Lacrimal patency, obstruction site, and patient discomfort (10-point VAS) were evaluated by a blinded radiologist. Results: Adequate contrast opacification was achieved in all cases. Obstruction was detected in 70/80 (87.5%) patients. Mean patient discomfort was 2.1 ± 1.3 VAS scale, lower than the values reported in the literature for conventional CT-DCG. No adverse reactions occurred. Conclusions: Non-cannulated CT-DCG with dropwise iodixanol instillation is a feasible and well-tolerated imaging technique that provides high diagnostic yield while preserving physiological tear flow. Further prospective, comparative studies are warranted to validate these findings.