Objective To investigate the technique and application of nasolacrimal duct imaging using MR hydrography.Methods Eight healthy volunteers(16 lacrimal ducts)and 17 patients affected by primary epiphora(32 lacrimal ducts)underwent MRl with three.dimensional fast recovery fast spin echo (3D-FRFSE)MR dacryocystography(MRD)sequence after sterile saline solution had been instilled into the conjunctival sac.For all patients affected by primary epiphora,FRFSE T2-weighted oblique coronal and axial images were obtained after MRD.All patients(32 lacrimal ducts)underwem lacrimal endoscopy.which served as a standard of reference for confirming MR findings.Results Eight cases of 16 normal lacrimal passages were showed by MR hydrography with administering topical sterile saline solution,which demonstrated the lacrimal sac well and whole course of the nasolacrimal duct.Endoscopic findings confirmed nasolacrimal duct obstruction secondary to chronic non-specific inflammation:the color of the mucosa of the nasolaerimal ducts was grey-red,and the obstructive sinuses were filled with nonelastic grey-white membrane.The accuracy of 3D-FRFSE MRD sequence in diagnosing obstructive level was 78%(25/32). The lacrimal ducts above the obstructive level showed watery hypo-intensity on 3D-FRFSE MRD.and the lacrimal ducts below the obstructive level could not be showed.Abnormal findings were presented in all cases of obstructive nasolacrimal ducts with Axi-FRFSET2 WI and Cor-FRFSET,WI sequences:long T2 fluid signals were seen in the lumens of tlle lacrimal sac and(or)nasolacrimal duct above the obstructive level. equal or slightly long T2 soft-tissue signals were seen in the lumens of the nasolaerimal duct below the obstructive level.and the mucosa of the ducts thickened Conclusion MR imaging performed after the topical administration of sterile saline solution can reveal normal nasolacrimal duct and is feasible in evaluating obstructive nasolacrimal ducts.