The Application Value Of Spectral Insufflation CT Combined Automatic Spectral Image Assist Technology Preoperatively In Evaluation Of Esophageal Cancer Staging

Part One: The influence of the automatic spectral image assist combined with low total dose of iodinated contrast medium injection based on body mass index(BMI)on radiation dose and image quality of chest CT enhancementBackground and Objective: As a landmark functional imaging technology,tube voltages of conventional spectral CT switch through 140 k Vp and 80 k Vp,Due to lack of individual preferences,spectral CT cannot effectively reduce the radiation dose in the process of scanning based on BMI values.The best scanning parameters can be selected according to patients' size and noise index by ASIA(automatic spectral imaging assist)technology,which can maintain the radiation dose similar to regular scan and optimize the image quality.The effective reduction of contrast injection dose based on the patients' weight can reduce the risk of adverse reactions.The aim of our study was to investigate the influence of ASIA combined with low total dose of iodinated contrast medium injection based on body mass index(BMI)on radiation dose and image quality of chest CT enhancement.Materials and methods: One hundred and twenty cases randomly divided into group A and B(60 patients respectively)were enrolled in our study.Patients were then divided into three sub-groups based on BMI value(14 cases in BMI<18.5 kg/m2,26 cases in 18.5 kg/m2?BMI<24.9 kg/m2 and 20 cases in BMI<18.5 kg/m2).Dual-phase chest CT enhancement was performed by using GE HD750 CT.Automatic spectral imaging assist(ASIA)technology were performed in group B with 300 mg I/kg contrast medium injection,while group A underwent conventional 120 k Vp CT with 450 mg I/kg contrast medium injection.Image analysis and measurement was performed by a radiologist with 10 years experience of CT diagnosis using GE Health Care AW 4.6 workstation.ROI including descending aorta at different layers(main pulmonary artery,tracheal bifurcation,right pulmonary artery and left/right atrium)were selected on monochromatic images via GSI spectral software.Group A and B were reconstructed with FBP and 50% ASIR,respectively.CT attenuation,image noise,CNR,subjective image quality scores,radiation dose and total dose of iodinated contrast medium for each group were calculated and evaluated.SPSS 19.0 was used for statistical analysis.The age,height,weight,BMI and radiation dose were compared using pared-samples T test.The objective and subjective analysis was measured by One-way ANOVA and Mann-Whiteney U test.Results: 1.Image noise comparison: The image noise in group A were dramatically lower than that in 40 Ke V during AP(P<0.05 for all),and higher than those in 70 Ke V(P<0.001 for all),and similar to those in 50 Ke V and 60 Ke V(P>0.05 for all).In terms of VP,image noise in group A were significant inferior to 40 and 50 Ke V(P<0.05 for all),and superior to those in 70 Ke V(P<0.001 for all),and similar to those in 60 Ke V(P>0.05 for all).2.CT attenuation comparison: The mean CT attenuation of 40 and 50 Ke V for descending aorta at the layers in MPA,TB,RPA and RLA in group B were significantly higher compared to that in group A during AP and VP(P<0.05 for 40 and 50 Ke V),and lower than those in 70 Ke V(P<0.001 for all),and similar to those in 60 Ke V(P>0.05 for all).3.CNR comparison: The CNR for descending aorta at the layers in MPA,TB,RPA and RLA on 40~60Ke V images for the normal size patients,and 40,50 Ke V for underweight and overweight in group B were all significantly higher than those in group A(P<0.05 for all),while others shows no significant difference(P>0.05).However,there were no significant differences in CNR of any ROI between 70 Ke V and group A,except for descending aorta at the layers in MPA and RPA for the overweight(P=0.038 and P=0.026,respectively).4.Subjective image quality evaluation: All scores of image noise score,anatomical details score and overall image quality score were equal to or more than three points,which can meet the clinical requirement.The monochromatic image in 40 Ke V showed higher anatomical details score,but lower image noise score and similar overall image quality score in contrast to those in group A(P<0.05 for all).50 and 60 Ke V exhibited higher anatomical details score and overall image quality score than those in group A,but lower and similar image noise score(P<0.05 for all).The 70 Ke V showed superior image noise score,inferior overall image quality score and similar anatomical details score(P<0.05 for all).5.Radiation dose and total dose of iodinated contrast medium injection comparison: There exist no statistical differences of CTDIvol,DLP and ED between groups at all BMI levels(P>0.05 for all).Iodine load in group B reduced by 33.33% per kilogram of body weight than group A.The total dose of iodinated contrast medium in group B were lower than that of group A in BMI<18.5kg/m2 and 18.5kg/m2?BMI<24.9 kg/m2(P<0.05 for all),but had no statistical differences in BMI>24.9 kg/m2(P>0.05).Conclusions: 1.Image noise of 40~60Ke V performed by ASIA can be effectively reduced or maintained,and promote the resolution and image quality compared to conventional 120 KVp image.2.There exist no statistical differences of CTDIvol,DLP and ED between ASIA and conventional 120 KVp image at all BMI levels.3.Iodine load in ASIA group reduced by 33.33% per kilogram of body weight than conventional 120 KVp image.The total dose of iodinated contrast medium in ASIA were lower than that of conventional 120 KVp image in BMI<18.5kg/m2 and 18.5kg/m2?BMI<24.9 kg/m2.Part Two: The Application value of Spectral insufflation CT combined “double low dose scanning” protocol preoperatively optimized for T stage on esophageal cancerBackground and Objective: Esophageal Carcinoma(EC)is one of common malignant tumors in digestive system.The mortality of EC is about 300 thousands of people per year around the world.In China,the most common pathology subtype is Esophageal Squamous Cell Carcinoma(ESCC).The correct T stage for ESCC by imaging preoperatively plays a critical role in the development,treatment and prognosis of the patients.Conventional CT has limitation in ESCC stage or restage after treatment.Esophageal insufflation CT(EICT)is a method of insufflating the esophagus into the stomach before the CT examination,fully expanding the esophageal cavity in order to achieve the goal of inflating the esophagus.Hence,we determined to evaluate the T stage for ESCC using low-dose spectral insufflations CT technique,and tried to discuss the accuracy of T stage preoperatively.Materials and methods: Seventy-five ESCC patients comfirmed by surgery or esophagoscopy randomly divided into three groups(25 patients respectively)were enrolled in our study.Dual-phase chest CT enhancement was performed by using GE HD750 CT.Automatic spectral imaging assist(ASIA)technology were performed in group B and C with 300 mg I/kg contrast medium injection,while group A underwent conventional 120 k Vp CT with 450 mg I/kg contrast medium injection.EICT were performed in group C.Image analysis and measurement was performed by a radiologist with 10 years experience of CT diagnosis using GE Health Care AW 4.6 workstation.Group A and group B,C were reconstructed with FBP and 50% ASIR,respectively.Contrast-to-noise ratio(CNR)of lesion-to-mediastinal adipose and radiation dose for three groups were measured and compared.Special imaging features were observed and recorded by two radiologists with 10 years diagnosed experience.T stages for ESCC were evaluated between groups.SPSS 19.0 was used for statistical analysis.The objective analysis was measured by One-way ANOVA.Compared to pathology result,sensitivity,specificiay and accuracy for T stage evaluation were measured between groups.Results: 1.Special imaging features for T stage evaluation: Hierarchy enhancement has significant different in discriminating T1/2 and T3 stage in medullary type of ESCC(P>0.05 for all).Combined using quantitative and qualitative analysis of adipose in front of vertebral body,there exists statistical difference in differential diagnosis of T3 and T4 stage in medullary type of ESCC(P <0.05 for all).2.Image quality and radiation dose comparison: CNRlesion-to-mediastinal adipose of group B and C were higher than that of group A(P<0.05);but has no difference between group B and C(P>0.05).CTDIvol,DLP and ED between groups shows no statistical difference(P>0.05).Iodine load in group B and C reduced by 33.33% per kilogram of body weight than group A.3.The sensitivity and accuracy in group C in terms of T1/2 stage diagnosis were higher than group A and B.With regard to T3 stage,the sensitivity and specificity in group C were higher than that of group A and B.The sensitivity,specificity and accuracy in diagnosis of T4 between groups were almost similar.Conclusions: 1.Spectral insufflation CT combined ASIA technology can optimize the CNR for ESCC,maintain the radiation dose and reduce contrast medium injection dose.2.Compared to conventional CT,spectral insufflation CT combined ASIA technology can promote the differential diagnosis between T1/2 and T3 stage.3.Combined using quantitative and qualitative analysis of adipose in front of vertebral body,the ability of differential diagnosis of T3 and T4 stage in medullary type of ESCC can be improved.Part Three: Combined Diagnosis of Spectral CT Parameters in Preoperative Assessment of Lymph Node Metastasis from Esophageal Squamous Cell Carcinoma using Logistic Regression and ROC CurveBackground and Objective: Regional lymph node migration is the primary and common site of esophageal squamous cell carcinoma(ESCC)metastasis.Preoperative CT diagnosis of lymph node status plays a guiding role for establishment of treatment.Several articles on CT for staging ESCC have argued that the pooled results of CT for the detection of lymph node metastases due to less sensitivity and accuracy for N stage.Spectral CT imaging achieve instantaneous switch between 80 k Vp and 140 k Vp,which concluded 40~140 Ke V monochromatic images with high differentiated ability.In this study,we determined the multivariate Logistic regression model in a retrospective cohort of patients for optimal cutoff value in identifying metastatic status from non-metastatic lymph node.Materials and methods: Sixty EC patients with 45 males and 15 females comfirmed by surgery or esophagoscopy were enrolled in our study.Dual-phase chest CT enhancement was performed by using GE HD750 CT.Image analysis and measurement was performed by two radiologists with 10 years and 20 years experience of CT diagnosis using GE Health Care AW 4.6 workstation.ROI were selected on 70 Ke V monochromatic images with optimal contrast-to-noise ratio via GSI spectral software.The spectral CT parameters(NIC,NICD,NIC ratio,Zeff,Zeff-c,Slope of 40~140 Ke V spectral curve)were measured during arterial phase and venous phase.SPSS 19.0 was used for statistical analysis.The significant spectral CT parameters of lymph node were selected using multi-logistic regression analysis.Binary Logistic regression was used for combined predictive probability calculation.Thresholds of quantitative parameters and diagnostic accuracy calculation were selected using ROC curve.Results: 1.We finally included 134 suspected lymph nodes in our study.IC,NIC,the slope of 40~70 Ke V,80~100 Ke V,110~140 Ke V,Zeff and Zeff-C of metastastic lymph node were higher than that of non-metastastic ones during two phases(P <0.05 for all);The difference and ratio of NIC between arterial phase and wenous phase of metastastic lymph node were lower than that of non-metastastic node(P <0.05 for all).2.ROC curve showed that IC,NIC,K40~70 Ke V,K80~100 Ke V,K110~140 Ke V,Zeff and Zeff-C during AP have medium diagnostic value,while other parameters' siginificance were lower.IC AP,NIC AP,Zeff AP and Zeff-C AP were selected using multi-logistic regression analysis,especially for IC AP.Threshold of 22.39 in IC AP generate 66.70% sensitivity,96.15% specificity and 78.40% accuracy.3.Binary Logistic regression result showed that the diagnostic value of combined parameters with IC AP and NIC AP was the highest.Threshold of 0.29 yield 70.73% sensitivity,96.15% specificity and 80.60% accuracy.4.Compared to the result according to conventional CT features,combined parameters with IC AP and NIC AP exhibited higher sensitivity(70.20% vs.64.63%),specificity(96.15% vs.78.85%)and accuracy(80.60% vs.70.15%)in differential diagnosis of metastastic lymph node.Conclusions: Combined parameters with IC AP and NIC AP using binary logistic regression analysis have a strong ability in differential diagnosis of metastastic lymph node,with higher sensitivity and specificity than single parameter.