| Objective:1.Comparison of MRI and Revolution CT in preoperative TN staging of rectal cancer in morphology2.Using energy spectrum multi-parameter imaging to analyze the correlation between the spectral parameters and preoperative TN staging of rectal cancer,and then dividing the cases into two groups,the metastatic lymph node groups and non-metastatic lymph nodes groups to investigate the diagnostic efficacy of different spectral parameters in metastatic lymph node groups and non-metastatic lymph node groupMaterial and Method:1.This study retrospectively analyzed a total of 76 patients from November 2017 to March 2019,all patients were confirmed pathologically to be rectal cancer.All patients underwent MRI and Revolution CT scans within two weeks before surgery.The scanning protocol consisted of fast self-selected echo(FSE)T1WI,T2WI axial diffusion weighted imaging(DWI)and multi-phase enhanced scan.The CT scan ranged from the diaphragmatic surface to the pubic symphysis level.A plain scan and a GSI dual-phased scan were performed.Two radiologists with more than 5 years of experience in diagnosing gastrointestinal tumors evaluated images and performed T and N staging based on morphological criteria of rectal cancer lesions and lymph nodes.The accuracy,sensitivity and specificity of T and N staging of MRI and CT were calculated based on the pathological results after resection and preoperative T and N staging.McNemar test was used to compare the two imaging methods in the diagnosis of preoperative TN staging of rectal cancer.P<0.05 was considered statistically significant2.This study retrospectively analyzed a total of 76 patients from November 2017 to March 2019,all patients were confirmed pathologically to be rectal cancer.All patients underwent Revolution CT scanning.The CT scan ranged from the diaphragmatic surface to the pubic symphysis level.A plain scan was firstly was performed at 120 kVp tube voltage.The dual-phase enhancement scan was performed in the spectral imaging scan mode with fast tube voltage switching between 80 and 140 peak kilo voltage.Using gemstone spectral imaging(GSI)General to analyze the obtained arterial and venous data and the observe the iodine concentration,water concentration,spectral curve slope,effective Z of rectal cancer lesions and lymph nodes.Then the cases were divided into two groups based on the pathological results,the metastatic lymph node group and non-metastatic lymph node group.Non-metastatic lymph nodes group includes NO staging patients,metastatic lymph node group includes N1 or N2 patients.Analysis of variance(ANOVA)was used to assess the iodine concentration,water concentration,spectral curve slope,effective Z of rectal cancer lesions and lymph nodes.Then the statistically significant parameters were evaluated by LSD-t test.Using Independent samples t test to analyze the corresponding spectral parameters of the metastatic lymph node group and non-metastatic lymph node group.Receiver operating characteristic(ROC)was performed and the diagnostic cutoffs were determined to distinguish between the metastatic lymph node group and non-metastatic lymph node group.The accuracy,sensitivity and area under curve(AUC)of corresponding parameters were calculated.P<0.05 was considered statistically significantResults:1.Among all 76 cases of rectal cancer,49 were males and 27 were females,the range of the age was 32 to 88 years old with an average age of 65.3 years.Pathological results after surgery revealed 6 T1 staging,21 T2 staging,40 T3 staging,9 T4s staging,54 NO staging,11 N1 staging,11 N2 staging.The overall accuracy of T staging by MRI was 82.9%(63/76),The overall accuracy of T staging by CT was 66.75(57/76).There was significant difference in overall accuracy between MRI and CT(P=0.031).The overall accuracy of N staging by MRI and CT was 76.3%(58/76)and 77.6%(59/76),respectively.There was no significant difference in overall accuracy between MRI and CT(P>0.05)2.54 NO staging patients were divided into non-metastatic groups,22 N1 staging patients were divided into metastatic groups.There was no significant difference between different T staging of water concentration in both arterial phase and venous phase.While different T staging of the iodine concentration,spectral curve slope and effective Z in both phases showed statistically significant(P<0.05).Further multiple comparisons revealed that,there was no significant difference in all spectral parameters between T1 and T2 stages in arterial phase and venous phase(P>0.05),while these spectral between T1 and T3,T1 and T4,T2 and T3,T2 and T4,T3 and T4 showed significant difference in arterial phase and venous phase(P<0.05).There was significant difference between different N staging of iodine concentration,water concentration,spectral curve slope and effective Z in both arterial phase and venous phase(P<0.05)Further comparisons showed that,no significant difference was observed in all spectral parameters between N1 and N2 stages in arterial phase and venous phase(P>0.05),while these spectral between NO and N1,NO and N2 showed significant difference in arterial phase and venous phase(P<0.05)Independent samples t test showed that the iodine concentration,water concentration,spectral curve slope and effective Z of non-metastatic lymph nodes group were lower than those of metastatic lymph nodes group in both arterial phase and venous phase,and the differences were statistically significant(P<0.05).The ROC curves of the iodine concentration,water concentration,spectral curve slope and effective Z of non-metastatic lymph nodes group and metastatic lymph nodes group in arterial phase and venous phase were plotted,and effective Z both has a better diagnostic efficiency,corresponding cutoff value were 8.7 and 8.91,AUC were 0.89 and 0.96,the sensitivity were both 86.36%and 86.36%,the specificity were 80.77%and 94.23%,respectivelyConclusion:1.There was a significant difference between Revolution CT and MRI in the diagnosis of preoperative T staging of rectal cancer in morphology,and MRI was superior to conventional CT.No statistical difference was observed between the two imaging methods in the diagnosis of N stage of rectal cancer2.The multi-parameter imaging of spectral CT is valuable in the diagnosis of preoperative T and N staging of rectal cancer and the differentiation of metastatic and non-metastatic lymph nodes. |
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