Quantitative diagnosis of fatty liver with dual-energy CT: An experimental study in rabbits

Objectives: To explore the correlation between fatty content of fatty liver and the difference of CT attenuation value in dual-energy CT, and to evaluate the value of dual-energy CT in the quantitative diagnosis of fatty liver in rabbits. Material and Methods: Dual-energy CT at 120 kVp and 90 kVp was performed in 16 rabbits of experimental groups that were induced to various degrees of fatty liver by feeding carbon tetrachloride (CCl4). Four healthy rabbits in the control group underwent dual-energy CT at the same time. The CT attenuation values of liver tissues at 120 kVp (H120), 90 kVp (H90) and the difference (ΔH) between them were obtained. The specimens of liver tissues were examined with freeze section (9 μm) and an oil red O stain histologically. The ratio of fatty content in liver to the liver volume (VP value) was measured using the image analyzer system. Results: The change of CT attenuation values between 120 kVp and 90 kVp was not obvious (ΔH between −0.4 HU and 1.4 HU) in the control group. The density of the liver in the experimental groups decreased differently, and the change in CT attenuation values between high and low energy levels were very clear. H120 values were between 51.0 HU and 91.7 HU and H90 values were between 37.0 HU and 89.2 HU. ΔH values were between 2.5 HU and 14.0 HU. Significant negative linear correlation (r = −0.92, −0.93, t = 8.51, 9.76, p < 0.001, 0.001, respectively) were found between VP values and H120 and H90, respectively, while significant positive linear correlation (r = 0.95, t = 11.89, p < 0.001) was found between VP values and ΔH. Conclusion: The amount and degree of fat in the fatty liver can be assessed exactly by dual-energy CT. It will be a potential new effective method for quantitative diagnosis of fatty livers.