Advantage of CT multi planar reconstruction technique for the measurement of nasolacrimal duct

SUNJi-hang; ZHANGCheng-yue; ZENGJin-jin; WUQian; YUGang; LIUYong; PENGYun

Abstract：Objective Comparison of CT multi planar reconstruction technique (MPR) and the conventional axial CT technique measurements of diameters of nasolacrimal ducts with unilateral congenital nasolacrimal duct obstruction .To ex‐plore the advantages of two methods for the measurements respectively .Methods 18 CT examinations of unilateral con‐genital nasolacrimal duct probing through operation failed obstruction were reviewed .The height ,and transverse diame‐ter ,vertical diameterand of nasolacrimal duct of initial segment ,the middle segment and the end segment of nasolacrimal duct were measured using the routine CT axial technique and MPR .Results The initial segment ,axial CT image meas‐urement and M PR measurement of the middle and distal nasolacrimal ductvertical diameter are obvious differences ( P <0.01) ,results show that measuring the transverse diameter ,the affected side terminal has the difference ( P < 0 .01) , more than themeasuring part is not significantly different ( P >0 .05) ,and MPR measurement can observe bent out of shape ,nasolacrimal duct openings ,two kinds of methods can beclearly observ in the ipsilateral than the contralateral ,the diameter increased significantly ,the difference is statistically significant ( P<0 .01) .Conclusion Compared with the con‐ventional axial CT image measurement method ,CT multiplanar reconstruction of nasolacrimal duct shape ,out of shape is more comprehensive ,the measurement results are more credible ,but has no effect on the accuracy of diagnosis .