多排低剂量螺旋CT鉴别肺结节:两种重建层厚比较

Detecting pulmonary nodules with two reconstruction slice thickness in 16-slice low dose helical CT

目的比较16排低剂量螺旋CT两种重建层厚对肺结节的数目、内部以及周边特征的检出情况。方法在健康人群低剂量胸部螺旋CT检查中,对80例疑似或确诊有肺部小结节患者的图像分别进行1.25 mm与2.50 mm层厚重建,共得到160组图像,所检出结节按直径分为≤5 mm组（第1组）、5~10 mm组（第2组）、≥10 mm组（第3组）,记录每组图像结节的数目、结节的边界清晰程度、边缘特征（分叶征、毛刺征）、密度（钙化、空洞）。结果两种重建层厚检测肺部结节数目差异无统计学意义,检测第1组结节的边界清晰程度、分叶征、钙化差异有统计学意义,但毛刺征、空洞差异无统计学意义,检测第2组及第3组结节的边缘特征、内部密度差异均无统计学意义。结论在胸部低剂量螺旋CT扫描过程中,可采用2.50 mm重建层厚扫描,设定图像噪声与重建层厚1.25 mm噪声相等,以进一步减少辐射剂量。

Objective To compare the performance of detecting and characterizing pulmonary nodules with 1.25 mm and 2.5 mm reconstruction slice thickness in 16-slice low dose spiral CT.Methods Eighty patients underwent low dose pulmonary CT for health check-up were enrolled because of suspected or diagnosed pulmonary nodules.All nodules were categorized into ≤5 mm（goup 1）,5—10 mm（group 2） and ≥10 mm（group 3） nodule.Images with 1.25 mm and 2.50 mm reconstruction slice thickness were generated for each of the patient.The number of nodules,internal structure（existence of calcification and cavity） and peripheral structure（clarities of edge,lobulation and spiculation signs） for each of the reconstruction were recorded.Results There was no statistical difference in the detected number of nodules between 1.25 mm and 2.50 mm reconstruction slice thickness.In Group 1,no statistical difference of detecting spiculation and cavity evaluation existed between the two reconstruction slice thicknesses,but nodule boundary,lobulation or calcification.In group 2 and 3,there was no difference for detecting nodule characterization between the two reconstruction slice thicknesses.Conclusion During low dose CT scanning for detection of pulmonary nodules,2.50 mm can be used for the same image noise as the 1.25 mm reconstruction slice thickness to provide further dose reduction.