Study About The Clinical Utility Of DECT With Dual Energy Scan In The Evaluation Of Gastric Cancer

Part One Evaluate the ability of DECT in detection whetherthe fat around the gastric cancer is infiltrated by measuringiodine concentration of the fat around the tumorObjective: To evaluate the ability of Dual-energy CT in detectionwhether the fat around the gastric cancer is infiltrated by measuring iodineconcentration of the fat around the tumor.Methods: Fifty-three patients (46men,7women, age range29~74, meanage59.8±9.4) with gastric cancer that was confirmed by endoscopyunderwent dual-energy scanning with Siemens second-generation dual-sourceCT. They accepted surgery within a week and hadcomplete pathological information. The iodine concentration of the fat aroundthe cancer in arterial phase and venous phase images was obtainedrespectively. The ROC curve was used to determine the iodine value of thebest threshold for judging the fat infiltration.Results: The iodine concentration was0.00±0.18mg/ml and0.17±0.25mg/m in group A(the fat was normal), respectively in the arterial andvenous phase. The iodine concentration was0.65±0.35mg/ml and1.08±0.43mg/ml in group B(the fat was infiltrated). In arterial phase, whenthe threshold value was0.15mg/ml, the sensitivity was100%, the specificitywas86.7%, the positive predictive value was95%, and the negative predictivevalue was100%. In venous phase, when the threshold value was0.62mg/ml,the sensitivity was86.8%, the specificity was100%, the positive predictivevalue was100%, and the negative predictive value was75%.Conclusion: The iodine concentration of fat around the gastric cancermeasured by Dual-energy CT can help us to distinguish whether the fat is infiltrated. Part Two Evaluation of advanced gastric cancer byspectroscopy curve of DECTObjective: Using dual-energy spectrum of software analysis, study withthe spectrum characteristics of the curve of the normal gastric and gastriccancer, normal fat and invasion fat, metastasis lymph node and gastric cancer,and analyze the differences and the contact between them.Methods: Forty patients (35men,5women, age range29~74, mean age60.2±8.5) with gastric cancer that confirmed by endoscopy underwentdual-energy scanning by Siemens second-generation dual-source CT. Theyaccepted surgery within a week and had complete pathological information,and all of them were confirmed that the fat around the tumor was infiltratedand had lymph node metastasis. Measure the CT value ofnormal stomach, gastric cancer, fat around the normal gastric wall, fat aroundthe gastric cancer, lymph nodes under different Kev, and then drawthe spectrum curves. Compare the trend curves of the different tissues.Results: Energy spectrum of the normal stomach and gastriccancer showed a slow downward trend in the curve, but not parallel. Thespectrum curve of normal gastric wall downward trend wassignificantly higher than the trend of gastric cancer during40Kev-80Kev, andnormal gastric wall CT value higher than the range of CT values of gastriccancer. In90Kev-190Kev, there was no significant difference between thenormal gastric wall and gastric cancer. Spectrum curve of thenormal fat within the40Kev-100Kev showed a clear upward trend. Invasionof the fat spectrum curve was flat, and the CT value was higher than normalfat. The energy spectrum curves of gastric cancer and lymph node metastasistended to decrease, more significant in40Kev-80Kev. In80Kev-190Kev the two curves were straight and roughly parallel.Conclusion: spectrum curve can help to distinguish betweennormal stomach and gastric cancer, normal fat and invasion fat and lymphnode metastasis. Part Three Evaluate the images quality of the differentvoltage conditions and the noise reduction capability of IRIS byusing dual-phase enhanced CT scanning the gastric cancerpatientsObjective: To compare the enhanced images of different voltageconditions by using dual-phase enhanced CT scanning the gastric cancerpatients, and evaluate the images quality and the noise reduction capabilityusing iterative reconstruction in image space (IRIS).Methods: Sixty patients (42men,18women, age range38~77, mean age57.7±8.7) with gastric cancer that was confirmed by endoscopy underwentdual-energy scanning with Siemens second-generation dual-energy CT. Theywere performed routine and enhanced scan using DECT with dual energymode. To determine the CT values of the tumor and the normal gastric indifferent images of different voltage conditions in the dual-phase enhancedimages, and then calculate difference of the CT value between the tumor andthe normal gastric, and to study if there is significant difference. To determinethe CT values and noise of the tumor and liver in different images of differentvoltage conditions, respectively in the different reconstruction dual-phaseenhanced images, then to study if there are significant differences in the noiseof the FBP-80kVp and IRIS-80kVp images, signal to noise ratio (SNR) of theFBP-DE and IRIS-80kVp images.Results:1. The difference of the CT value between the tumor andnormal gastric: Both in the arterial and venous phase images, there were statistically significant differences between the80kVp and the dual-kilovolt(P<0.05). The difference of80kVp image was more significant.2. Noise:There were statistically significant differences in the image of tumor and liverobtained in the arterial and venous phase between the FBP-80kVp andIRIS-80kVp (P<0.05). The noise of FBP-80kVp image was more significant.3.SNR: There were statistically significant differences between the FBP-DE andIRIS-80kVp images, except the SNR of the liver in arterial phase images. TheSNR was higher in IRIS-80kVp image.Conclusion: The images of the low voltage (80kVp) have a higherdegree of enhancement between the tumor and the normal gastric, and theIRIS can make the noise reduction. Associate the low voltage and IRIS canmake the image optimized.