Study Of Gallstone Composition By Spectral CT Analysis

Objective: To explore the differences of parameters(for example,CT mean(CT),CT slope(Slope),effective atomic number(Zeff),calcium-water ratio(CWR))and spectral curves of spectral CT in various gallstones with different components,and to explore the diagnostic value of spectral CT in differentiating pure cholesterol gallstones from impure ones.Method: Spectral CT was used to scan gallstones in vitro and IR spectrum was used as the gold standard of determining the composition and classification of gallstones.With these methods,gallstones were divided into pure and impure cholesterol gallstone groups.Furthermore,the impure cholesterol gallstones were divided into calcium bilirubinate group,calcium stearate group and calcium carbonate group.ROI was outlined in the axial,coronal and sagittal maximum planes of gallstones.Mann-Whitney U test was used to test the differences of parameters between different gallstone groups.A receiver operating characteristic(ROC)curve was used to determine the optimal parameters' cutoff value of pure and impure cholesterol stone group.Area under the curve(AUC)was used to compare these two groups of gallstones.The sensitivity,specificity,positive predictive value and negative predictive value were obtained by the best distinction method.Results: There were significant differences in CT parameters between pure and impure cholesterol stone groups(P<0.01).However,there were no significant differences in parameters between calcium bilirubinate and calcium stearate groups(P>0.05).CT slope was the best diagnostic parameter to distinguish pure and impure cholesterol stones: AUC was 0.956.Taking Slope?0.98 as pure cholesterol stone,Slope<0.98 as impure cholesterol stone as the diagnostic standard,sensitivity was 81.25%,specificity was 100%,the positive predictive value was 100%,and the negative predictive value was 78.57%.Conclusion: Spectral CT can be used as an effective reference method to distinguish pure cholesterol stones from impure ones.There were differences in spectral CT manifestations and energy spectrum curves of gallstones with different compositions.Spectral CT has an important reference value for the analysis of gallstone components.