Objective To observe the value of electron density map(EDM)from spectral CT combined with CT features in differentiating acute and chronic osteoporotic vertebral fractures(OVF).Methods Thoracic and/or lumbar spectral CT data of 48 patients with acute complicated chronic OVF were retrospectively analyzed.Totally 110 fractured vertebrae were enrolled,including 53 vertebrae with acute fractures(acute group)and 57 with chronic fractures(chronic group).The quantitative parameters of spectral CT,including CT values of conventional 120 kVp polyenergetic image(PI,i.e.routine CT images)and 40,70,100 keV virtual monoenergetic images(VMI),effective atomic number(Z-eff)and electron density(ED),as well as routine CT finding were compared between groups,and those being significantly different were included in multivariate logistic regression to screen the independent risk factors for acute OVF and construct a combined model.Receiver operating characteristic(ROC)curves were drawn to evaluate the efficacy of each single independent risk factor and the combination for differentiating acute and chronic OVF.Results Significant differences of all spectral CT quantitative parameters,also of routine CT findings including interruption of vertebral endplate,cortical folds,increased vertebral density,gas within vertebral body and vertebral compression degree were found between groups(all P＜0.05).Logistic regression analysis showed that CTPI(OR=0.855,P=0.005),ED(OR=16.432,P=0.005),cortical folds(OR=0.038,P=0.034)and increased vertebral density(OR=0.025,P=0.013)were all independent risk factors for acute OVF.The area under the curve(AUC)of the above single parameters for identifying acute and chronic OVF was 0.870,0.889,0.879 and 0.866,respectively,all lower than that of the combined model(0.977)(Z=3.47,3.73,2.95,2.71,all P＜0.05).Conclusion Spectral CT EDM combined with CT findings could effectively differentiate acute and chronic OVF.