Objective:To investigate the predictive value of the quantitative parameters of dual-layer detector spectral CT in arterial and venous phases for the differentiation degree and the E-cadherin protein expression of gastric cancer.Methods:This was a cross-sectional study. The preoperative data from the dual-layer detector spectral CT images among 183 patients with gastric adenocarcinoma confirmed by operation and pathology was retrospectively analyzed from October 2021 to October 2022 in the First Affiliated Hospital of Fujian Medical University. According to the differentiation degree and E-cadherin protein expression of gastric cancer, all patients were divided into the moderately well differentiated group ( n=82) and the poorly differentiated group ( n=101), as well as the E-cadherin-negative group ( n=80) and the E-cadherin-positive group ( n=103). The CT images in arterial and venous phases were used to reconstruct the virtual monoenergetic images (VMI) at 40, 50, 60, 70, 80, 90, and 100 keV, effective atomic number (Z eff) images and iodine concentration (IC) images. The CT values (CT keV) from VMI, Z eff and IC were measured, and the normalized Z eff (NZ eff) and the normalized IC (NIC) were calculated. Independent-sample t test or Mann-Whitney U test were used to compare the differences in quantitative parameters between groups. The logistic regression analysis was used to screen for the independent predictors, after which a combined prediction model was constructed. The receiver operating characteristic curves were used to evaluate the predictive efficiency of the parameters for the differentiation degree and the E-cadherin protein expression of gastric cancer. Results:There were statistically significant differences in CT 40 keV to CT 70 keV, NZ eff and NIC in dual-phase, as well as Z eff and IC in the venous phase between the moderately well differentiated group and the poorly differentiated group ( P<0.05). The combined prediction model was constructed by CT 40 keV ( OR=1.03, 95% CI 1.02-1.05, P<0.001) in arterial phase and CT 40 keV ( OR=1.05, 95% CI 1.03-1.07, P<0.001) and Z eff ( OR=1.32, 95% CI 1.06-1.65, P=0.015) in venous phase, of which the area under the curve (AUC) for the prediction of the moderately-well group and the poor group was 0.932 (95% CI 0.897-0.967), with a sensitivity of 90.1% and a specificity of 85.4%. Between the E-cadherin-negative group and the E-cadherin-positive group, CT 40 keV and NZ eff in arterial phase, as well as CT 40 keV to CT 70 keV, Z eff, NZ eff, IC and NIC in venous phase, had statistically significant differences ( P<0.05). The AUC for the combined prediction model established by CT 40 keV ( OR=1.02, 95% CI 1.01-1.04, P<0.001) and Z eff ( OR=1.33, 95% CI 1.09-1.63, P=0.006) in venous phase was 0.800 (95% CI 0.736-0.864), with a sensitivity of 95.0% and a specificity of 60.2%. Conclusion:The combined prediction model from the quantitative parameters of dual-layer spectral detector CT can be used to predict the differentiation degree and the E-cadherin protein expression of gastric cancer preoperatively.

Purpose To explore the clinical application value of dual-layer detector spectral CT combined with half volume contrast agent in detecting the liver metastases in portal vein phase.Materials and Methods Ninety-six patients with liver metastases diagnosed by liver enhanced CT in the First Affiliated Hospital of Fujian Medical University from November 2021 to June 2022 were prospectively studied.They were randomly divided into two groups by using the contrast agent administration calculation method based on body surface area.The conventional polyenergetic image(CI)of patients in the conventional contrast agent group(48 cases with 18.6 gI/m2 body surface area iodine contrast agent)was constructed in the portal vein phase,and the 40-70 keV(5 kiloelectron voltage)virtual monoenergetic imaging(VMI)was reconstructed for patients in the semi contrast agent dose group(48 case with 9.3 gI/m2 body surface area iodine contrast agent).The image noise,CT value and contrast noise ratio in the two groups were measured and compared.Besides,the image quality was scored with a 5-point method,and the consistency of subjective scores between two radiologists were evaluated.Results The VMI noise at 40-70 keV was(10.26±1.38)Hu,(9.59±1.35)Hu,(9.15±1.31)Hu,(8.80±1.32)Hu,(8.58±1.31)Hu,(8.40±1.31)Hu and(8.27±1.33)Hu;while the CI noise was(10.86±1.13)Hu.It revealed that the VMI noise at 45-70 keV was lower than the CI noise(t=-3.885,-5.343,-6.449,-7.180,-7.756 and-8.132,P<0.001).There was no significant difference between VMI and CI noises at 40 keV(t=-1.800,P>0.05).With the decrease of energy level,CT value of normal liver parenchyma,and contrast noise ratio values of liver parenchyma and liver metastases gradually increased,at the 40 keV level,the values of which were(148.31±21.34)Hu,8.81±2.83 and 8.18±2.85;at the 45 keV level,the values were(130.10±16.95)Hu,7.66±2.46 and 7.48±2.55;at the 50 keV level,the values were(116.19±13.55)Hu,6.60±2.08 and 55.40±13.77,reaching the highest at 40 keV level,while the CI values were(118.02±7.02)Hu,5.69±1.11 and 5.77±1.41.Therefore,the value of 40 keV and 45 keV VMI was significantly higher than CI(t=3.804,4.883,4.462,all P<0.05;t=2.854,3.465,3.378,all P<0.05),respectively.There was no significant difference between 50 keV VMI and CI(t=-0.612,1.739,2.208,P>0.05).The subjective score in the overall quality of VMI images was higher than that of CI at 40-50 keV(t=9.628,7.508,3.514,P<0.05).The subjective scores of the two physicians were good consistent among image contrast,image noise and overall image quality(Kappa=0.766,0.749 and 0.661,P<0.05),respectively.Conclusion VMI at 40-50 keV can provide better image quality and display ability of liver metastases than CI images at portal vein phase with a 50%reduction in contrast agent dose.