CT Perfusion Imaging Combined With Energy Spectrum Imaging To Evaluate The Intramedullary Infiltration Transition Zone Of VX2 Malignant Bone Tumors In Rabbits

Objective To analyze the parameters of CT perfusion imaging and energy spectral imaging,compare them with pathological specimen,study the differences in parameters between the marginal solid area,micro-invasive area and pure edema area of rabbit VX2 malignant bone tumors,in order to explore the value of CT perfusion imaging and spectral imaging in evaluating intramedullary transition of malignant bone tumors.Methods 50 New Zealand white rabbits were selected to establish models of VX2 malignant bone tumor at the right tibia metaphysis.The models were examined by CT perfusion examination and energy spectrum examination three weeks after models were established,then the models were executed immediately.The right tibia of the models were taken for gross specimens and pathological sections.Observe the gross specimen and pathological sections,the margin areas of the models were divided into marginal solid area,the micro-invasive area and the pure edema area.Corresponding three areas of pathological sections to CT imaging,measuring the CT perfusion parameters(blood volume BV,blood flow BF,surface permeability PS,meantransit time MTT)and spectrum parameters(energy spectrum curve K,iodine-based value,water-based value)in different areas by CT Perfusion4 software and GSI Viewer software.Using one-way ANOVA to compare the differences between the parameters of the three areas,plotting the Receiver Operating Characteristic Curves(ROCs),calculating the accuracy of distinguishing different areas by different parameters according to the area under curve(AUC).Using SPSS 25.0 software for statistical analysis.Results(1)Preparation,imaging and pathological analysis of the model rabbit 50 models were established,among them 12 models died during feeding and imaging,3 models showed no tumor in tibia,1 model showed pathological fracture,a total of 34 models were included in the experiment,all of them completed CT perfusion examination and CT energy spectrum examination,and all they were prepared into pathological sections.(2)Statistical results of CT perfusion parameters in different regions of tumor margins The BV values of the marginal solid area,micro-invasive area and pure edema area at the tumor margins were respectively12.785±0.532 ? 12.553±0.579 ?8.327±0.394(P=0.000),the BF values were respectively 80.399±4.439?59.939±4.916?40.383±4.588(P=0.000),the MTT values were respectively 9.955±1.153?9.939±1.141?10.478±0.991(P=0.139),the PS values were respectively 44.384±2.267?37.577±2.477?33.397±2.019(P=0.000),There were significant difference in BV?BF?PS values among three areas,and no difference in MTT among three areas.Comparing within groups,there were no significant difference in BV values between marginal solid area and micro-invasive area(P=0.095),MTT values had no significant difference between marginal solid area and micro-invasive area,marginal solid area and pure edema area,micro-invasive area and pure edema area(P values were respectively 0.961,0.104,0.440).All other parameters had significant difference between each other.(3)Statistical results of energy spectral imaging parameters in different areas of tumor margins The slope K values of the marginal solid area,micro-invasive area and pure edema area at the tumor margins were respectively 3.533±0.128 ? 2.563±0.203 ?4.758±0.222(P=0.000),the iodine-based value of three areas were respectively 63.924±1.863?53.109±3.437?44.903±2.592(P=0.000),the water-based value of three areas were respectively 1028.159±8.249?1030.221±15.189?1029.952±12.218(P=0.765).There were significant difference in slope K and iodine-based values among the three areas,and no difference in water-based value among the three areas.Comparing within groups,water-based value had no significant difference between marginal solid area and micro-invasive area,marginal solid area and pure edema area,micro-invasive area and pure edema area(P values were respectively 0.502,0.494,0.938).All other parameters had significant difference between each other.(4)Accuracy of different parameters to distinguish different regions BV and BF had highest accuracy in differentiating micro-invasive area from pure edema area(AUC=1),PS was next(AUC=0.878);BF had highest accuracy in differentiating marginal solid area from micro-invasive area(AUC=1),PS was next(AUC=0.976),BV had lower accuracy in differentiating marginal solid area from micro-invasive area.BV?BF and PS all had highest accuracy in differentiating three areas(AUC=1);MTT can not differentiate different areas from each other area(AUC<0.7).Iodine-based value and slope K value had highest accuracy in differentiating marginal solid area from micro-invasive(AUC=1);slope K value had highest accuracy in differentiating micro-invasive area from pure edema area(AUC=1),iodine-based value next(AUC=0.961);water-based value can not differentiate different areas from each other area(AUC<0.7).Conclusion(1)The BF and PS value of CT perfusion can effectively distinguish marginal solid areas,micro-invasive areas and pure edema areas of tumor,and BF has highest accurary.BV can effectively distinguish areas with tumor cells and pure edema area.(2)The iodine-based value and slope K value of energy spectral CT can effectively distinguish marginal solid areas,micro-invasive areas and pure edema areas of tumor,and slope K value has the highest accurary.