| Objective: To explore the value of spectral CT quantitative parameters in the preoperative staging of colorectal cancer(colorectal cancer,CRC),to explore the value of spectral CT quantitative parameters in the evaluation of colorectal adenocarcinoma,and to explore the relationship between K-ras gene state and the spectral CT performance including the CT characteristics and the CT quantitative parameters of colorectal cancer.Materials and methods: From November 2015 to December 2017 in Lanzhou University Second Hospital,a total of 66 cases of colorectal adenocarcinoma confirmed by operation and pathology,who had two-stage enhancement data of spectral CT were collected.All patients underwent K-ras gene detection,38 males and 28 females,aged 31-76 years.In some cases,the location of the tumor and enlarged lymph nodes around the bowel during operation were correlated with CT images.The details are as follows:1.In the staging study of colorectal cancer,patients with intraoperative labeling were selected,which were T2,T3,and T4 a staging of 36 cases,and single-energy CT values,iodine(fat)concentrations,and fat(iodine)concentration and energy spectrum curve slope;23 cases of peripheral lymph node metastases were compared.The single-energy CT values,iodine(water)concentration,water(iodine)concentration,and the slope of the energy spectrum curve of the primary lesion and the metastatic lymph nodes were compared;2.In the grading study of colorectal cancer,single-energy CT values at 40-140 keV,iodine(water)concentrations,water(iodine)concentrations,normalized iodine concentrations(NIC),and energy spectrum curve slope were compared in high-and low-grade adenocarcinomas.The Receiver operating characteristic(ROC)curve was used to analyze the statistically significant quantitative parameters for the differential diagnosis of high and low grade colorectal adenocarcinoma sensitivity and specificity.3.In the study of the correlation between K-ras gene status and CT imaging signs and quantitative parameters of energy spectrum,the imaging signs includes: tumor location,thickening of the intestinal wall,fat infiltration around the bowel,and whether there is enlargement of lymph nodes;Spectral CT quantitative parameters include: single-energy CT values,iodine(water)concentration,water(iodine)concentration,NIC,and curve slope.The curve slope and NIC were calculated according to the following formula: slope =(CT40 keV-CT100 keV)/60;NIC = lesion iodine(water)concentration / aortic iodine(water)concentration.Finally,statistical analysis was performed.The measurement data were analyzed by independent sample t test.The count data were analyzed by chi-square test.Results: 1.There were statistically significant differences in the spetral CT quantitative parameters of the peripheral fat of the T3 and T4 a stages in the arterial and the venous phase(P<0.05),and the T4 a staging parameters were higher than the T3 staging ones;There was no significant difference in the parameters of primary lesions and metastatic lymph nodes;2.The iodine(water)concentration,NIC,curve slope,and CT value of 40~130keV in the arterial phase were significantly different between the high and low grade adenocarcinomas(P<0.05),and the parameters in the high grade group were all higher than the low group ones.The ROC curve showed that the diagnostic efficiency of each parameter from high to low was 60 keV CT value,curve slope,iodine concentration and NIC;3.Of the 66 cases of CRC,32 cases(48%)showed mutations in the K-ras gene.K-ras mutant CRC mostly located in the right colon(16/32),lesions in the intestine showed an eccentric thickening(30/32),and there was an increased number of lymph nodes around the bowel(30/32).Iodine(water)concentration(21.28±3.98 vs 12.83±9.18),NIC(0.20±0.05 vs 0.12±0.09),the slope of the curve(2.29±0.62 vs 1.33±0.89)and the the CT value of 40~70keV in K-ras mutant CRC was higher than K-ras mutant wild-type ones.Conclusions: 1.The quantification parameters of spectral CT,such as iodine(water)concentration,iodine(fat)concentration,fat(iodine)concentration,single energy CT value and curve slope,can distinguish the perianal fat invading and lymph node properties in CRC’s T and N stages;2.In the grading assessment of CRC,the iodine(water)concentration,single-energy CT value,NIC,and curve slope can be used to identify high-grade and low-grade CRC.The parameters of high-grade CRC are all higher than low-grade CRC;3.CT imaging features(tumor location,thickening of the intestinal wall,increase in peristaltic lymph nodes),and quantitative parameters of spectral CT(iodine concentration,low keV single energy CT,NIC,and curve slope)can reflect the status of K-ras gene. |
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