Value Of Spectral CT Imaging For Identifying Tuberculous And Malignant Pleural Effusions

Objective To evaluate the diagnostic value of dual energy spectral CTimaging in differentiating tuberculous from malignant pleural effusions.Methods Retrospectively analyzed67hydrothorax patients (31withtuberculous pleural effusions and36with malignant pleural effusions, confirmedpathologically) who underwent plain CT with spectral imaging mode. Spectral CTrelated parameters for the hydrothorax were obtained: effective-Z and iodine andwater concentrations from the material decomposition images. Spectral HU curve(CT value as function of photon energy) was generated from the set ofmonochromatic images, and the slope k of the curve was further calculated ask=[HU(40keV)-HU(90keV)]/50. Results from the two groups were analyzed withindependent samples t test.Receiver operating characteristic curves were generatedto determine parameters for optimizing sensitivity, specificity and accuracy in thisstudy.Results (1)The slope of the spectral HU curve for malignant pleuraleffusions （0.45±0.22） was statistically higher than that for tuberculous pleuraleffusions （0.23±0.08）,(t=5.23, P<0.05).（2） The effective-Z values fortuberculous and malignant pleural effusions were （7.67±0.04） and（7.78±0.11）, respectively, with significant ifference between them (t=5.45,P<0.05).（3） The iodine concentrations were (0.19±0.0）7g/L and （0.37±0.18）g/L in the tuberculous pleural effusions and malignant pleural effusions,respectively, with significant difference (p<0.05). While there was no differencefor the water concentrations between the tuberculous pleural effusions （1068.27±0.01） g/L and malignant pleural effusions （1067.48±0.01） g/L,(p=0.60>0.05).Conclusion Spectral CT provided additional parameters than conventionalCT for effectively differentiating tuberculous pleural effusions from malignantpleural effusions. Spectral CT may be used to better differentiate tuberculouspleural effusions from malignant pleural effusions.