The Application Of Spectrum CT(GIS) And MRI For The Preoperative Assessment Of N Staging In Rectal Cancer

Objective:Firstly,through the application of spectral CT imaging,quantitatively and qualitatively evaluating regional lymph node characteristics in preoperative rectal cancer.Secondly,to study the value of gemstone spectral CT in the preoperative N staging of rectal cancer compared with conventional CT and MRI.Thirdly,to analyse qualitatively the factors related to lymph node metastasis.Material and Method:To collect prospectively patients suspected clinically rectal cancer from September 2015 to December 2016.All patients who were cleaned enema were inject water 500-1000 ml through the anus before scanning,and.GE Discovery CT was used to perform routine abdominal plain scan and GSI-enhanced scan.Within a week,some patients undergo the GE 3.0T MRI routine and enhanced scan.Evaluating and recording the location,maximum diameter,the density,iodine value,NIC and spectral curve slope of primary rectal cancer.The group,number,morphological characteristics(long diameter,short diameter,the ratios of short to long diameters,S/L),the density,iodine concentration(IC),NIC and spectral curve slope of the lymph node were evaluated and recorded,and then calculate the ratio of spectrum curve slope and the NIC of the lymph node to the primary rectal cancer.The group of the lymph node,number,morphological characteristics and the signal in the sequence of DWI were evaluated and recorded in patients of the MRI examination.The datas of each parameters were evaluated by the independent samples t test,chi-square test,single factor analysis,multiple factor regression analysis,etc.Results:There were 86 cases of rectal cancer(53 men,33 women),aged 39-77 years,with an averageage of(56±10)years old,with a medianage of 56 years.Among them,47 patients had MRI examination.59 cases had lymph nodes metastasis and 27 had no.Among 473 lymph node found in CT imaging,97 lymph nodes detected in the completely corresponding group of CT and pathology of 59 patients with stage N1-2 were divided into metastatic lymph nodes group and 113 lymph nodes detected in 27 cases of N0 patients were divided into the non-metastatic lymph node group.T test showed that morphological parameters in the metastatic lymph nodes group were higher.And that the CT density and IC in arterio-venous phase of metastatic lymph nodes were lower than these of non-metastatic lymph nodes.The area under ROC of the S/L,the IC in arterial phase,the CT density in arterial phase,the IC in venous phase,the CT density in venous phase,and the short diameter of lymph nodes were as follows: 0.847,0.841,0.792,0.758,0.746,0.704.The sensitivity and specificity of each threshold and threshold were 82.4%,75.0%,0.721;84.3%,75.3%,16.89(100ug/cm3);80.4%,74.1%,69.18HU;70.6%,66.7%,20.31(100ug/cm3);78.4%,68.5%,74.78HU;55.9%,79.6%,7.82 mm.The ratio of λHu and NIC in the group of Metastatic lymph node were lower than that in non-metastasis group,and the former is close to 1.The area under curve of ROC of the ratio of λHu and NIC were 0.879,0.835.Using the ratio of λHu closed to 1.12 as the criterion,the sensitivity and specificity were 86.3%,77.8%.Using the ratio of NIC closed to 1.03 as the criterion,the sensitivity and specificity were 82.4%,75.9%.68 patients were evaluated accurately in the N staging with conventional CT.The accuracy,sensitivity,specificity,PPV and NPV were 79.07%,81.36%,74.07%,64.52%,respectively.MRI correctly evaluated 38 cases of N staging,the accuracy,sensitivity,specificity,PPV and NPV were respectively 80.85%,82.14%,78.95%,85.19%,75%.74 patients were diagnosed correctly through the Spectrum CT,and the accuracy,sensitivity,specificity,PPV and NPV were 88.14%,81.48%,91.23%,and 75.86%,respectively.The accuracy,sensitivity,specificity,negative predictivevalue and positive predictive value of preoperative N staging of rectal cancer with Spectrum CT were higher than that of conventional CT and MRI.For N staging rectal cancer,consistency check display conventional CT and MRI can believe the existence of consistency,but consistency is poorer(Kappa= 0.670,p <0.001).And there was consistency between the Spectrum CT and MRI,and consistency is better(Kappa= 0.896,p <0.001).Related analysis revealed that the gender and age,the location of primary focus,and maximum diameter had no point between metastatic and non-metastatic lymph nodes.The age,tumor gross type,histological type,degree of infiltration and differentiation are the transfer factors of lymph node.Multi factor regression analysis showed that the degree of tumor infiltration is a major factor of lymph node metastasis of rectal cancer.Conclusion:1.The ratio of spectrum curve slope,the ratio of NIC,the lymph node short diameter,the ratio of short to long diameter,and arteriovenous iodine base value have high efficiency of diagnosis in the metastatic lymph node of rectal cancer.2.Spectrum CT is more valuable than conventional CT and MRI in the diagnosis of preoperative N staging of rectal cancer.And there is a better consistency between the Spectrum CT and MRI.3.The age of patients,the gross type of primary tumor,histological type,differentiation degree,infiltration degree can predict lymph node metastasis of rectal cancer.And the infiltration degree of tumor is the main factor affecting lymph node metastasis of rectal cancer.