多层螺旋CT计算心室容积的准确性及最佳层厚选择

The accuracy of ventricular volume measurement and the optimal slice thickness by using multislice helical computed tomography

目的(1)确定Simpson方法计算心室容积的最佳层厚;(2)评价多层螺旋CT计算心室容积的准确性。方法采用多层螺旋CT(东芝Aquilion)扫描系统对14个人的左室铸型和15个右室铸型进行扫描。分别以2.0、3.5、5.0、7.0及10.0mm层厚重建左、右心室短轴多平面重组(multiplanarreformattedimage,MPR)图像。采用标准Simpson法计算左、右心室铸型的容积。心室铸型的实际容积通过铸型排除水的容量来计算。结果各层厚计算的心室容积均高估相应心室的实际容积[左心室高估值介于(3.21±5.95)ml至(12.58±8.56)ml之间,右心室高估值介于(10.22±8.45)ml至(23.91±12.24)ml之间]。各层厚计算的心室容积均与相应的实际心室容积高度相关(左心室r值均>0.97,右心室r值均>0.95);心室容积的高估程度与选择的层厚呈显著正相关(左心室r=0.998,右心室r=0.996)。当层厚降至5mm时,计算的心室容积对实际容积的高估值与2mm层厚相比不再差异有统计学意义。结论采用多排Simpson法计算左、右心室容积时,5mm层厚是最有效率的层厚。MSCT可以准确计算左、右心室容积。

Objective To determine the optimal slice thickness for ventricular volume measurement by tomographic multislice Simpson＇s method and to evaluate the accuracy of ventricular volume measured by multislice helical computed tomography （MSCT） in human ventricular casts. Methods Fourteen human left ventricular （LV） and 15 right ventricular （RV） casts were scanned with MSCT scanner by using a scanning protocol similar to clinical practice. A series of LV and RV short-axis images were reconstructed with slice thickness of 2 mm, 3.5 mm, 5 mm, 7 mm, and 10 mm, respectively. Multislice Simpson＇s method was used to calculate LV and RV volumes and true cast volume was determined by water displacement. Results The true LV and RV volumes were （55.57 ± 28.91 ） ml, and （ 64.23 ± 24.51 ） ml, respectively. The calculated volumes from different slice thickness ranged from （58.78 ± 28.93 ） ml to （68.15±32.57） ml for LV casts, and （74.45 ± 27.81） ml to （88. 14 ± 32.91） ml for RV casts, respectively. Both the calculated LV and RV volumes correlated closely with the corresponding true volumes （all r 〉0.95, P 〈0. 001 ）, but overestimated the corresponding true volume by （3.21 ±5.95） to （12.58 ± 8. 56） mlforLVand （10.22±8.45） to （23.91±12.24） ml for RV （all P〈0.01）. There was aclose correlation between the overestimation and the selected slice thickness for both LV and RV volume measurements （ r = 0. 998 and 0.996, P 〈 0. 001 ）. However, when slice thickness was reduced to 5.0 mm, the overestimation became nonsignificant for slice thickness through 2.0 mm to 5.0 mm, and also for both LV and RV volume measurements. Conclusion Both LV and RV volumes can be accurately calculated with MSCT. A 5 mm slice thickness is enough and most efficient for accurate measurement of LV and RV volume.