Objective To observe the value of extracellular volume(ECV)and relative electron density(RED)based on dual-layer detector spectral CT(DLCT)for identifying colon cancer invasion into serous membrane.Methods Sixty-two patients with pathologically confirmed colon cancer with blurred pericolonic fat gap on CT images were retrospectively collected,including 18 cases of T4a stage tumors with serous membrane invasion and 44 cases of T2-T3 stage without serous membrane invasion.The arterial,venous and delayed phase DLCT images under 40 keV showing the largest diameter of colon cancers were analyzed.The iodine concentration(IC)and RED of the pericolonic fat around tumor-bearing and tumor-free intestines,as well as of the abdominal aorta or the common or external iliac artery were measured,while normalized IC(NIC)and difference of RED(REDdiff)of pericolonic fat around tumor-bearing and tumor-free intestines in each phase and ECV in delayed phase were calculated.The above parameters were compared between tumors with different stages,and for those with significant differences,the receiver operating characteristic curves were drawn,and the areas under the curve(AUC)were calculated to evaluate and compare the efficacies for identifying invasion of serous membrane in T4a stage colon cancer.Results Compared with T2-T3 stage colon cancers,T4a stage colon cancers were found more often occurred in patients aged ＜50 with higher proportion of lymph node metastases(both P＜0.05),also higher values of NIC and REDdiff on images in different phases,as well as ECV in delayed phase images(all P＜0.05).The AUC of arterial,venous and delayed phase NIC for differentiating T2-T3 and T4a stage colon cancers ranged from 0.868 to 0.902,while of REDdiff ranged from 0.848 to 0.903,all without significant difference(all P＞0.05).The AUC of delayed phase ECV was 0.948,not significant different with that of delayed phase NIC and REDdiff,arterial phase NIC nor venous phase REDdiff(all P＞0.05).Conclusion Based on DLCT,ECV and RED could be used to identifying serous membrane invasion of colon cancer when blurred pericolonic fat gaps were noticed.
维普
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