A new complex diagnostic protocol for the diagnosis of nasolacrimal duct obstruction: Simultaneous dacryocystography and dacryoscintigraphy using SPECT/CT

Objectives Epiphora, an abnormal overflow of tears, is commonly caused by tear drainage system anomalies including nasolacrimal duct obstruction (NLDO). To assess morphological abnormalities dacryocystography by computed tomography (CT-DCG) is used when CT contrast material is syringed into the lacrimal drainage system. To evaluate the function of the system dacryoscintigraphy (DSCI) is the most readily available non-invasive method.

Methods 14 patients with clinically suspected obstruction of nasolacrimal duct were recruited into this study. 5 MBq 99mTc sodium pertechnetate was instilled with a micropipette into the lacrimal lake of both eyes and simultaneously 90x 10 sec dynamic images was acquired in 128x120 matrix with a high resolution gamma-camera (NuclineTh/22, Mediso). The drainage was characterized based on the time-activity curve generated on the ROIs for the left and right eyes and nasolacrimal ducts. (InterviewXP, Mediso) If obstruction was confirmed SPECT/CT (Anyscan SC, Mediso) images (20sec/64 frame, 360° degree, 256x256 matrix SPECT and 100mAs, 120kV CT) was performed to localize the site of obstruction before and after syringing with contrast material (ioversol, Optiray 350, Covidien) of the nasolacrimal tear drainage system.

Results Using DSCI the tear could be detected mostly in the upper part of the nasolacrimal drainage system, but with CT-DCG the contrast material could be forced to get to the Hasner’s valve. DCG can provide anatomical details of the nasolacrimal drainage system. The result of a DCG can be totally different from that of a DSCI because of the fact that during DCG high pressure contrast injections are administered resulting in diverse viscosity and surface tension.

Conclusions SPECT/CT camera offers the opportunity to perform these two sensitive investigations simultaneously enabling us to localize anatomically the exact position of the radiolabelled tear, to identify any blockade and to propose surgical intervention