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 × (0.75 × P + 0.25 × 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 ≥ 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 ≤ 0.002) and similar accuracy to _pre L-S at the other threshold levels (P ≥ 0.144). Conclusion: Portal-phase contrast-enhanced CT has a similar, or even greater, accuracy than unenhanced CT in diagnosing fatty liver.