Preliminary Study on Three-plane Reconstruction Technique of Retrograde Inflated Lacrimal Duct CT Imaging Based on the Trend of Nasolacrimal Duct
OBJECTIVE To evaluate the accuracy and safety of the three-plane reconstruction technique of retrograde inflated lacrimal duct computed tomography(CT)imaging based on the trend of nasolacrimal duct in examining the patency of the nasolacrimal duct and lacrimal sac in patients with pre-sacicular lacrimal duct obstruction.METHODS A total of 43 cases(57 eyes)of pre-sacicular lacrimal duct obstruction from October 2022 to December 2023 were selected.Axial CT scans were performed before inflation to assess the presence of air in the nasolacrimal duct and lacrimal sac.Patients with incomplete air filling in the nasolacrimal duct and lacrimal sac on pre-inflation axial CT scans were subjected to retrograde inflation and pressure monitoring using a self-designed and manufactured system through the inferior nasal meatus.CT axial scans were performed after air filling,and the maximum inflation pressure during imaging was recorded.Three-plane reconstruction of lacrimal duct CT axial scans and analysis of its patency in three planes,axial,coronal,and sagittal,based on the trend of nasolacrimal duct were conducted.The results were compared with intraoperative findings to assess accuracy.Simultaneously,complications and adverse reactions were observed to evaluate safety.RESULTS(1)General situation:Before retrograde inflation,among the 43 cases(57 eyes),three cases(four eyes)had both the lacrimal sac and nasolacrimal duct filled with air,while 40 cases(53 eyes)had incomplete air filling.(2)Retrograde inflation test:After retrograde inflation,among the 53 eyes with incomplete air filling,both the nasolacrimal duct and lacrimal sac were fully filled with air in 33 eyes,while no air filling was observed in 20 eyes.Intraoperative verification showed that the nasolacrimal duct and lacrimal sac were unobstructed in 33 eyes,while 12 eyes among the 20 eyes had true obstruction in the lower segment of the nasolacrimal duct,and eight eyes had no obstruction in the nasolacrimal duct.The sensitivity of this examination method was 80.4%,specificity was 100.0%,and accuracy was 84.9%.The optimal reference range for nasal cavity inflation pressure was 8～9 kPa.(3)Complications and adverse reactions:No complications or adverse reactions were observed during or after the examination.CONCLUSIONS The three-plane reconstruction technique of retrograde inflated lacrimal duct CT imaging based on the trend of nasolacrimal duct can clearly display the bilateral nasolacrimal duct throughout the process,aiding in the assessment of nasolacrimal duct and lacrimal sac patency in patients with pre-sacicular lacrimal duct obstruction.It is safe and has certain guiding significance for the selection of clinical treatment procedures.
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