螺旋CT眼眶容积测量方法的研究

Investigation of Methodology in the Measurement of Orbital Volume with Computed Tomography

目的 探讨测量眼眶容积简便、省时又相对准确的CT成像方法。资料与方法以鼻科疾患就诊行16层螺旋CT扫描20例患者，眼眶正常，眼眶区及其周围未见占位性病变。双侧眼眶分别行容积再现（VR）成像，测得容积归入VR组；以层厚／层间距为2mm／2mm、2mm／4mm、2mm／5mm、3mm／3mm、3mm／5mm横断位重建五组图像，其余各种参数保持一致，并分别命名为A组、B组、C组、D组及E组。对各组测量得到的眼眶容积进行统计学分析。结果所得各组数据左右侧差异均无统计学意义。以VR组数据作为参照标准，A组误差率及差别的范围均最小，为2．42％和0．42％～4．40％，E组与其之间的差别最大，为7．35％，D组与其之间差别的范围最大为0．35％～7．75％。结论A组层厚及层间距均为2mm重建图像测量眼眶容积省时、方便、准确，可应用于各类型CT扫描仪。

Objective To evaluate methodology in the measurement of orbital volume with computed tomography （CT）. Methods Measurement of normal orbital volume was assessed in the axial images reconstructed by different slice thickness and interslice distance, and three dimensional images with volume rendering （3 D-VR） acquired by 16 row helical CT in 20 patients who performed computed tomography due to nasosinal abnormalities. Results There was no significant difference between the left orbit and the right in the measurement of orbital volume in each group. 3D-VR was the best in the measurement of orbital volume. Difference of the measurement results between 3 D-VR and the axial images reconstructed by slice thickness of 2mm and interslice distance of 2 mm was the least with a mean difference of 2.42% and range of difference from 0.42% to 4.40%. Difference of the measurement results between 3D-VR and the axial images reconstructed by slice thickness of 3 mm and interslice distance of 5mm was the biggest with a mean difference of 7.35%. Conclusions The axial images reconstructed by slice thickness of 2 mm and interslice distance of 2 mm were better than those reconstructed by other slice thickness and interslice distance in the measurement of orbital volume, and could be available in CT scanners of all kinds.