Combined application of isotropic Three-Dimensional fast spin echo (3D-FSE-Cube) With 2-point Dixon fat/water separation (FLEX) and 3D-FSE-Cube in MR Dacryocystography.

Objective: To evaluate image quality of magnetic resonance dacryocystography (MRD) using three-dimesional fast spin-echo -Cube (3D-FSE-Cube) and 3D-FSE-Cube-Flex sequences to examine the lacrimal drainage system (LDS). Methods: 21 healthy volunteers underwent 3D-FSE-Cube and 3D-FSE-Cube-Flex MRD after topical administration of compound sodium chloride eye drops. Two radiologists assessed LDS images in a blinded fashion. The signal-to-noise ratio of fluid-filling and the contrast-tonoise ratio of fluid-turbinate were compared between the two sequences. Overall image quality, sharpness, artefacts, visualization of anatomical structures, and visibility of LDS segments were also compared. Results: Overall image quality, visualization of anatomic structures, and artefact were significantly better on 3D-FSE-Cube-Flex MRD (p < 0.001, respectively). when compared to 3D-FSE-Cube. 3D-FSE-Cube showed lower fluid-filling signal-to-noise ratio and fluid-inferior turbinate CNR (all p < 0.001). IIn comparison with D- SE Cube-Flex, 3D-FSE-Cube produced superior visibility of the upper drainage segments (superior canaliculi, p = 0.003; common canaliculus, p = 0.033; inferior canaliculi, p < 0.001), but inferior in lower-LDS visibility (lacrimal sac, p = 0.001; nasolacrimal duct, p < 0.001). There was no difference in the total number of segments visualized per LDS between the two sequences (p = 0.068). Conclusions: 3D-FSE-Cube-Flex demonstrated superior image quality and visibility of the lower LDS segments. 3D-FSE-Cube showed an advantage in visualizing the upper LDS segments. The combination of these sequences can improve LDS visibility. Advances in knowledge: 3D-FSE-Cube-Flex provides robust water & fat separation and mitigates lower LDS-associated inhomogeneity artefacts. 3D-FSE-Cube shows optimal upper LDS visualization. The combined application of these sequences is a non-invasive and effective method for assessing LDS disease.