基于体模的肺内磨玻璃密度结节容积测量准确性研究

The accuracy of volumetric measurement of pulmonary ground-glass opacity nodules based on the chest phantom

目的评价64层螺旋CT计算机辅助测量模拟磨玻璃密度结节(ground-glass opacity nodule)体积的准确性,分析管电流对结节体积测量准确性的影响。方法制作胸部体模和13枚模拟磨玻璃密度结节,采用GE64层螺旋CT,分别用7组不同的管电流(30,60,90,120,150,180 mA和210 mA)进行扫描,扫描图像采用0.625 mm层厚、骨算法进行重建后传送至工作站,使用Lung VCAR软件计算模拟磨玻璃密度结节的体积。对7种电流条件下所测结节体积与结节标准参考体积分别进行相关分析,对7组计算结果的相对百分误差(relative percent error,RPE)的平均值进行比较分析。结果 7种扫描电流条件下13枚模拟磨玻璃密度结节均能够被软件成功分离并计算出各自体积,各组所测结节体积与标准参考体积均有明显相关性(P值均小于0.05),在电流为30,60,90 mA条件下,CT对模拟磨玻璃密度结节体积的测量较标准参考体积偏低,三组的RPE分别为(-5.63±8.60)%,(-6.07±7.49)%,(-5.50±8.31)%,而电流为120,150,180 mA和210 mA条件下CT对模拟磨玻璃密度结节体积的测量较标准参考体积偏高,四组RPE分别为(2.32±8.05)%,(3.06±8.18)%,(4.71±7.63)%,(3.05±7.79)%。结论采用CT测量磨玻璃密度结节体积的准确性较好,不同的CT扫描电流可以对结节体积测量产生影响。

Objective To evaluate the effect of various tube currents on accuracy of volumetric measurement of ground-glass opacity nodules.Methods A chest phantom and 13 artificial ground-glass opacity nodules with known volume were scanned using a 64-section computed tomography（CT） scanner at different tube currents（30,60,90,120,150,180,210 mA）.All data were reconstructed with slice thickness of 0.625 mm and bone algorithm.Automated nodule volume measurements were performed using computer-assisted volume measurement software.Nodule volumes measured by software were compared with the reference-standard volume of ground-glass opacity nodules.Correlation coefficient was used for statistical analysis.The relative percent error（RPE） between the CT measured volume and the reference-standard volume of ground-glass opacity nodules was measured.Results All volumes measured by MSCT at different tube currents were correlated with the reference-standard volume.The volumes of ground-glass opacity nodules measured at 30,60,90 mA were underestimated compared with the reference standard volume,and their mean RPEs were（-5.63±8.60）%,（-6.07±7.49）%,（-5.50±8.31%）,respectively.While there was substantial overestimation of volume at 120,150,180 and 210 mA,and the mean RPEs were（2.32±8.05）%,（3.06±8.18）%,（4.71±7.63）%,（3.05±7.79）%,respectively.Conclusion Computer-assisted volume measurement is a promising method for quantification of ground-glass opacity nodule volume.And the different tube currents could have effects on the accuracy of volumetric measurement.