| Objectives To explore the average CT value,effective atomic number(Zeff),slope of energy spectrum attenuation curve(slope)and calcium water ratio(calcium water)of gallstones in gemstone spectral imaging(GSI)To explore the diagnostic value of GSI condition and conventional spiral CT scanning condition in the diagnosis of biliary negative stones;to study the accuracy of measuring the size of stones under different single energy GSI conditions.Methods A total of 108 biliary stones were selected during the period from November2018 to March 2021,and the stones were removed by the General Surgery of the Affiliated Hospital of North China University of Technology.The stones were intact and unbroken,and the size was greater than 5 mm.The infrared spectrum analyzer was used as the"gold standard"for the diagnosis of biliary calculi.There were 81 single component stones.The stones were divided into four categories:cholesterol stones,calcium bilirubinate stones,calcium carbonate stones and hydroxyapatite stones.The stones were scanned by GSI and conventional spiral CT with Revolution energy spectrum CT.The difference of CT,Zeff and CWR of stones with different components was compared by analysis of variance,and the difference of Slope was compared by rank sum test.Then 81 stones were scanned by X-ray,42 of them were not developed and were negative stones.The phantom was scanned with GSI and conventional CT120k V,and the detection rate of negative stones under different conditions was compared by tests,and the difference in CT values of negative stones and bile under different conditions was compared by analysis of variance.The image stone size was measured at 40 kev-140 ke V(interval 10 ke V)under GSI condition.Paired sample t test was performed between the measured stone size and the actual stone size(the result measured by vernier caliper was"gold standard")to compare the accuracy of measurement results under different conditions.Results Analyzed the composition of the stones with an infrared spectrum analyzer.Among the 108 stones,81 stones could be identified as a single component.The 81gallstones were divided into 4 groups:50 were cholesterol stones and 19 were calcium bilirubin stones.Calcium carbonate stones,9 calcium carbonate stones,and 3hydroxycarbonate apatite stones.The average CT values of Zeff,Slope,CWR,and120k V are:cholesterol stones 7.67±0.88,-0.89(-1.54--0.13),-0.00±0.00,16.33±3.01HU;bilirubin Calcium stones 10.42±0.65,18.21(12.11-22.39),0.43±0.10,761.46±223.46HU;calcium carbonate stones 15.73±0.64,36.34(34.64-37.45),0.73±0.16,1398.32±265.04HU;Hydroxyapatite 15.78±0.58,37.12(35.43-38.64),0.72±0.11,1483.23±185.31 HU.According to statistical analysis,the Zeff,Slope,CWR,and CT values under 120k V of calcium carbonate stones and hydroxycarbonate apatite were not statistically different(P>0.05).There were differences between the other groups.Statistically significant(P<0.05).Under single energy conditions,there was no statistically significant difference in the CT values of calcium carbonate stones and hydroxycarbonate apatite(P>0.05),and the differences in CT values of the other stones were statistically significant(P<0.05).Compared with conventional spiral CT scan,the detection rate of negative stones was significantly higher in GSI scan(χ~2=5.316,P=0.021).At 120k V,the average CT value of stones and bile was compared,and the difference was not statistically significant(t=0.953,P=0.245).When the single energy is70ke V,the difference in CT values of stones and bile is not statistically significant(t=-0.848,P=0.399),and the difference under the other single energy is statistically significant(P<0.05).In GSI scanning mode,there was no significant difference between the measured stone size and the actual stone size.Conclutions 1 Under GSI scanning conditions,the energy spectrum parameters can not distinguish calcium carbonate from hydroxyapatite.According to CT value,conventional spiral CT scan can distinguish cholesterol,gall pigment and calcium carbonate or hydroxyapatite stone.Therefore,the energy spectrum CT scan has no advantage over conventional CT in distinguishing stone components,but increases radiation dose.2 The detection rate of GSI scanning condition is higher than that of conventional spiral CT scanning condition.The single energy of 70ke V is equivalent to the mixed energy of120k V,which is not conducive to the detection of gallstones.3 With the increase of energy,the accuracy of measuring the size of stone becomes higher and higherFigure 13;Table 8;Reference 124... |
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