Contrast-enhanced computed tomography for the diagnosis of fatty liver: prospective study with same-day biopsy used as the reference standard.

PURPOSE: The study purpose was to prospectively determine the accuracy of contrast-enhanced CT in diagnosing fatty liver using same-day biopsy as the reference standard. MATERIALS AND METHODS: One hundred seventy-nine potential living liver donors underwent unenhanced and portal-phase contrast-enhanced hepatic CT and subsequent liver biopsy on the same day. Attenuation difference between the liver and the spleen on unenhanced (( pre ) L-S) and contrast-enhanced (( post ) L-S) images and blood-subtracted hepatic attenuation on contrast-enhanced images (( post ) L-B), calculated by [L - 0.3 x (0.75 x P + 0.25 x A)]/0.7 where L, P and A represent the attenuation of the liver, main portal vein and abdominal aorta, respectively, were obtained. The accuracy of these indices in diagnosing fatty liver according to various threshold levels, 5%-30% histological steatosis in increments of 5%, was compared using ROC analysis. RESULTS: The area under the ROC curve for ( pre ) L-S, ( post ) L-S and ( post ) L-B was 0.663-0.918, 0.712-0.847 and 0.821-0.923, respectively, depending on the threshold levels of hepatic steatosis. The accuracy of ( pre ) L-S and ( post ) L-S did not differ (P >or= 0.054), despite a trend towards a lower accuracy with ( post ) L-S. ( post ) L-B yielded higher accuracy than ( pre ) L-S at threshold levels of 5% and 10% (P or= 0.144). CONCLUSION: Portal-phase contrast-enhanced CT has a similar, or even greater, accuracy than unenhanced CT in diagnosing fatty liver.