Objective To assess the value of spectral CT in differentiating benign and malignant serous cavity effusion in vitro.Methods 41 plastic tubes filled with serous cavity effusion underwent spectral CT imaging.The gemstone spectral imaging(GSI)viewer was used to measure the mean CT values of water -iodine concentration, iodine -water concentration,monochromatic images(40 -140KeV,interval of 5KeV),140KVp QC,and EFF -Z. Slope of spectral curve was measured also.Based on clinical and pathological diagnosis,30 cases of benign and 11 cases of malignant serous cavity effusion were compared.The difference of the spectral characteristic parameters was evaluated statistically by independent -samples t test using SPSS 18.0.Results The EFF -Z,water -iodine concentration,iodine -water concentration,and slope of spectral curve[7.26 ±0.25,(1 021.82 ±6.37)mg/mL, (-3.23 ±1.53)mg/mL,0.26 ±0.12]of benign serous cavity effusion showed no statistically significant differences between the malignant group[7.31 ±0.10,(1 016.17 ±5.32)mg/mL,(-3.06 ±1.18)mg/mL,(0.24 ±0.10), t =0.652,2.016,0.332,0.482,all P >0.05 ].There were statistically significant differences on 55 -140 KeV between the two groups[(4.87 ±7.13)and (10.66 ±6.70),(7.17 ±6.48)and (12.71 ±5.94),(9.58 ±6.11) and (14.96 ±5.65),(11.63 ±5.97)and (16.77 ±5.52),(13.31 ±5.93)and (18.36 ±5.52),(14.66 ± 5.98)and (19.52 ±5.52),(16.06 ±6.06)and (20.90 ±5.63),(17.03 ±6.10)and (21.42 ±5.88), (17.58 ±6.12)and (22.29 ±5.59),(18.05 ±6.14)and (22.74 ±5.49),(18.52 ±6.17)and (23.19 ± 5.51),(18.74 ±6.20)and (23.33 ±5.46),(19.16 ±6.20)and (23.80 ±5.47 ),(19.30 ±6.26 )and (23.87 ±5.45),(19.57 ±6.26)and (24.19 ±5.48),(19.66 ±6.28)and (24.21 ±5.43),(19.92 ±6.31) and (24.46 ±5.44),(20.00 ±6.32)and (24.53 ±5.43),t =2.339,2.474,2.544,2.489,2.456,2.356,2.301, 2.060,2.231,2.223,2.206,2.161,2.188,2.138,2.162,2.122,2.114,2.104,all P <0.05].However,there were no statistically significant differences on 40 -50 KeV[(-5.51 ±11.82)and (0.96 ±11.59),(-0.41 ±9.77) and (5.75 ±9.85),(2.47 ±8.21)and (8.19 ±8.11),t =1.559,1.785,1.984,all P >0.05].The difference be-tween benign and malignant effusion was statistically significant on 140KVp QC also [(10.25 ±6.96,16.60 ±6.84) (t =2.601,P =0.013)].Conclusion Some spectral CT characteristic parameters especially 55 -140 KeV mono-chromatic images can differentiate benign and malignant effusion.Spectral CT maybe afford a new method to differenti-ate benign and malignant effusion.

Objective To evaluate the ability of two sets parameters of the volome rendering technich(VRT)with multislice spiral CT(MSCT)to display the normal inner ear.Methods Fifty-eight inner ears of twenty-nine healthy volunteers were scanned and reconstructed with VRT.The images of VRT were recombinated with two sets(A,B)of parameters.Results The semicirculares、cochlea,vestibule,fenestra cochleae and vestibuli of inner ear could be visualized clearly by VRT images with"A"group's parameters.The vestibuli was displayed unsharply by VRT images with"B" group's parameters.Conclusions The double-threshold segmentation matching with manuleditor of VRT was successfully used to separate the inner ear from the temporal bone.And the semicirculares,cochiea,vestibule,fenestra cochleae and vestibuli of inner ear could be displayed clearly by VRT images of"A"group's parameters(threshold:256～765,935～1019,brightness:42,opacity:70).