The Application Of Dual-layer Detector Spectral CT In The Diagnosis Of Colorectal Cancer

Objective:To explore the diagnostic value of dual-layer detector spectral CT(DLCT)quantitative parameters(iodine density,effective atomic number,single energy CT value in the range of 40-100keV and slope of energy spectrum curve)in T staging of colorectal cancer,to explore the diagnostic value of dual-layer detector spectral CT quantitative parameters in detecting metastatic lymph nodes of colorectal cancer;to explore the value of quantitative parameters of dual detector spectral CT in judging the status of p53 gene in colorectal cancer.Materials and methods:The data of 49 patients with pathologically confirmed colorectal cancer who underwent abdominal DLCT examination from December 2019 to December 2020 were retrospectively analyzed.There were 33 males and 16 females.The average age was 61 years old,and the median age was 63 years old.p53 gene was detected in 36 cases.The details are as follows:1.In the study of T staging of colorectal cancer,a total of 46 patients were included.The iodine density,effective atomic number,single energy CT value in the range of 40-100keV and slope of energy spectrum curve of tumors in different T staging were compared.2.In the study of metastatic lymph nodes of colorectal cancer,83 lymph nodes,31 metastatic lymph nodes and 52 non-metastatic lymph nodes were included.The differences of spectral CT parameters between metastatic and non metastatic lymph nodes were compared.The parameters with statistical differences were analyzed by receiver operating characteristic curve(ROC),and the diagnostic efficiency of each parameter was compared.3.In the study of the relationship between p53 gene status in colorectal cancer,36 cases were included.The arterial and venous dual phase iodine density,effective atomic number,single energy CT value in the range of 40-100kev and slope of energy spectrum curve were measured in mutant and wild-type colorectal cancer,and the differences of spectral CT parameters between the two groups were compared.Result:1.In the T staging study,there were no significant differences in spectral CT parameters between the early group(T1-T2)and the late group(T3-T4),including iodine density,effective atomic number,single energy CT value in the range of 40-100keV and slope of spectral curve.2.In the study of lymph node metastasis,31 metastatic lymph nodes and 52 non-metastatic lymph nodes were included in the study.The iodine density,effective atomic number and energy spectrum curve slope of metastatic lymph nodes in both arterial and venous dual phase were lower than those of non-metastatic lymph nodes.There were significant differences in iodine density and slope of energy spectrum curve in the arterial phase between the two groups.The AUC of iodine density in arterial phase was 0.795,sensitivity was 0.704,specificity was 0.722;the slope of energy spectrum curve in arterial phase was 0.809,sensitivity was 0.778,specificity was 0.722.3.In the study of p53 gene status,32 cases were included,including 20 cases of mutant CRC and 12 cases of wild-type.There were more p53 mutations in the right colon(7 cases)than in the wild type(0 cases),and the difference was statistically significant(P=0.029).The iodine density in arterial phase(1.33±0.42)of p53 mutant was higher than that in wild-type(1.03 ± 0.34),the slope of energy spectrum curve in arterial phase(1.59±0.53)was higher than that in wild-type(1.20± 0.49),and the 40keV monoenergetic CT value in arterial phase(150.06 ± 35.09)was higher than that in wild-type(125.55± 27.11).Conclusion:1.There is no significant difference in DLCT quantitative parameters among different T staging groups of colorectal cancer.2.DLCT quantitative parameters have a certain value in differentiating lymph node metastasis of colorectal cancer patients,and the slope of energy spectrum curve in arterial phase is better than iodine density.3.There were significant differences in tumor location and DLCT quantitative parameters(arterial phase iodine density,arterial phase energy spectrum curve slope,arterial phase 40keV single energy CT value)among different p53 gene status groups.