64层螺旋CT动态增强扫描对结直肠癌肠外浸润判别函数的研究

目的 研究64层螺旋CT动态增强扫描结直肠癌肠外浸润的判别函数,以期提高结直肠癌肠外浸润诊断的准确性和特异性.方法 回顾性分析2007年6月至2008年12月49例结直肠癌患者的49个肿块,术前行64层螺旋CT动态增强扫描.每个肿块取1～2个层面,共96个层面.根据病理结果将96个层面分为肠外浸润组和非肠外浸润组,将2组动态增强后各时间点(10、15、20、25、30、35、40、45、50、55、60、65、70、75 s)肿块CT值与肿块处肠外5 mm范围内组织的CT值的差值进行判别分析,求出结直肠癌肠外浸润的判别函数.将CT形态学判别肠外浸润的结果和求出的判别函数判别的结果与病理结果进行对照.应用方差分析比较2组各时间点CT值差值的差异性.结果 肠外浸润组CT值差值范围为(43.6±27.8)～(52.3±30.8)HU,非肠外浸润组CT值差值范围为(100.4±20.3)～(116.2±21.4)HU.其中肠外浸润组20 s和40 s时的CT值差值分别为(43.6±27.8)和(50.9±27.8)HU;非肠外浸润组20 s和40 s时的CT值差值分别为(102.0 ±16.9)和(116.2±21.4)HU.2组各时间点CT值差值的差异有统计学意义(F=6.278,P<0.01).经判别分析,得到判别函数(D)=-3.450+0.023X1+0.017X2-0.001X12-0.001X22+0.002X1×X2,其中X1表示20 s CT值差值,X2表示40 s CT值差值.根据结直肠癌CT形态学表现正确判断69个层面,误判27个层面,其中20个层面非肠外浸润误判为肠外浸润,诊断肠外浸润的敏感性为82.5%,特异性为64.3%,准确性为71.9%.应用判别函数正确判断85个层面,误判11个层面,其中5个层面非肠外浸润误判为肠外浸润,诊断肠外浸润的敏感性为85.0%,特异性为91.1%,准确性为88.5%.结论 结直肠癌肠外浸润64层螺旋CT动态增强的判别函数可以提高肠外浸润诊断的准确性和特异性.

Discriminant function analysis for pericolic infiltration in colorectal cancer with dynamic enhanced 64-slice spiral CT

Objective To evaluate the efficacy of discriminant function analysis for pericolic infiltration in colorectal cancer on enhanced 64-slice spiral CT and to improve the diagnostic accuracy and specificity of pericolic infiltration. Methods Dynamic enhanced 64-slice spiral CT was performed in 49 colorectal cancer patients (49 masses in total) before surgery. One or two slices were selected for each mass, with a total of 96 slices. The 96 slices were classified into two groups (pericolic infiltration or nonpericolic infiltration group) according to pathological data. Discriminant analysis was performed on the CT values between the mass and the corresponding pericolic tissue 5 mm from the mass at different time points as follows; 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, and 75 s. The discriminant function was calculated, and the pericolic infiltration determined by discriminant function and CT morphology were compared with the pathological results. The CT values in pericolic and non-pericolic infiltration groups at different enhancement time points were assessed using analysis of variance. Results The mean CT values ranged from (43. 6 ±7. 8) HU to (52. 3 ±0. 8) HU in the pericolic infiltration group, and ranged from (100.4±20.3)HU to(116.2±21.4)HU in the non.perieolic infiltration group.At 20 s and 40 s,the mean CT vshle8 were(43.6±27.8)HU and(50.9±27.8)HU in the perleolic infiltration group, (102.0±16.9)HU and(116.2 ±21.4)HU in the non-perieolic infiltration group,respectively.The mean CT value in the pericolic infiltration group was significantly lower than that in the non-pericolic infiltration group at all contrast enhancement time points(F=6.278,P<0.01).A diseriminant function Was obtained as follows:D=-3.450+0.023Xl±0.017X2-0.00lX12-0.001X22+0.002X1×X2. Based on the CT morphology of colorectal cancer,69 slices were identified correctly and 27 slices were fulsely interpreted.the sensitivity.speeificity and accuracy for perieolic infiltration determination were 82.5%,64.3%and 71.9%.respectively.Based on diseriminant function,85 slices were identified correctly and 11 slices were falsely interpreted.the sensitivity,specificity and accuracy were 85.0%.91.1%and 88.5%,respectively.Conclusion The discriminant function with dynamic enhanced 64-slice spiral CT can improve the diagnostic accuracy and specificity of perieolic infiltration in eolorectal cancer patients.