Biopsy-proven Nonsteatotic Liver in Adults: Estimation of Reference Range for Difference in Attenuation between the Liver and the Spleen at Nonenhanced CT

Abstract

Purpose:To establish the reference range for hepatic attenuation minus splenic attenuation difference (CT L 2 S ) values on nonenhanced computed tomographic (CT) images obtained in adults with a biopsy-proved nonsteatotic liver and determine the CT L 2 S criterion for diagnosing hepatic steatosis. Materials and Methods:This retrospective study was institutional review board approved, and all subjects had provided written informed consent. The CT L 2 S was measured in 315 liver donor candidates (207 men, 108 women; mean age, 31.5 years 6 10.1 [standard deviation]) who underwent nonenhanced CT of the liver and subsequent ultrasonographically guided liver biopsy on the same day. Nonenhanced liver CT was performed with a 16-section multidetector scanner in 154 individuals and with a 64-section multidetector scanner in 161 individuals. Biopsy specimens were analyzed for degree of hepatic steatosis and iron deposition. The CT L 2 S reference range was determined according to Clinical and Laboratory Standards Institute guideline C28-A3 in individuals with a histologically proved nonsteatotic liver. The sensitivity of nonenhanced CT for the diagnosis of 5% or greater and 30% or greater hepatic steatosis with use of the lower limit of the reference range as the diagnostic cutoff was determined. The effects of subject age and sex, CT scanner type, and hepatic iron on the CT L 2 S were evaluated by using multiple linear regression analysis. Results:Ninety-six subjects (48 men, 48 women) were found to have a histologically proved nonsteatotic liver, with an estimated reference range for CT L 2 S values of 1-18 HU. With a CT L 2 S of less than 1 HU as the criterion for hepatic steatosis, the sensitivities of nonenhanced CT for 5% or greater and 30% or greater hepatic steatosis were 18.6% (29 of 156 subjects) and 67 % (26 of 39 subjects), respectively. Subject age had a signifi cant but negligible effect on CT L 2 S (0.076-HU increase per year of age, P = .009), subject sex and scanner type had no effects on CT L 2 S , and hepatic iron deposition signifi cantly increased the CT L 2 S (1.434-HU increase per increase in iron deposition grade, P = .011). Conclusion:The histologically proved reference range of CT L 2 S values for nonsteatotic livers was 1-18 HU. A CT L 2 S of less than 1 HU could be used as a conservative criterion for diagnosing hepatic steatosis with nonenhanced CT more consistently.q RSNA, 2011

MDCT classification of steatotic liver

“…Therefore, the final number of patients analyzed was 51 and the prevalence of patients without steatosis was 27.5% (n = 14). These data are similar to those reported in the recently published study by Park et al [16], where the prevalence of patients without steatosis was 30.5%.…”

“…Despite the widespread use of this approach, the cut-off of DLS for nonenhanced CT images used to distinguish steatotic livers from nonsteatotic livers has not been determined definitively, with published studies involving different cut-off values ranging from − 10 to 5 HU [19][20][21][22]. In a recent paper published in Radiology [16], the use of HU less than 1 as the DLS threshold was proposed, whereas we observed a specificity of 86% using a threshold of − 1 HU. Using a threshold of 55 HU of DLS in the arterial phase, we obtained a specificity of 92%.…”

Specificity of unenhanced CT for non-invasive diagnosis of hepatic steatosis: implications for the investigation of the natural history of incidental steatosis

“…Many studies have subsequently evaluated the use of CT in the setting of NAFLD [26,[28][29][30][40][41][42][43][44]. In most investigations, the spleen has been used as an internal reference standard, either subtracting its attenuation value from that of the liver, or reporting the result as a liver/ spleen attenuation ratio.…”

“…Mean body mass index (BMI) was 23.4±3.0 kg/m 2 . Portions of this study cohort have been the focus of previous prospective investigations evaluating different parameters [27][28][29].…”

Importance of imaging and recent developments in diagnosis of nonalcoholic fatty liver disease

“…CT was quite accurate for the diagnosis of grade 2-3 steatosis but was not as accurate for detecting grade 1 steatosis. In addition, liver parenchymal attenuation in CT may be affected by some factors, including the presence of excess iron and glycogen in the liver and the certain drugs such as amiodarone and methotrexate, acute hepatitis or acute toxic hepatic injury and cirrhosis [15,39,40] . Therefore, in patients with hemochromatosis and hemosiderosis, liver attenuation values are unreliable for detecting fat infiltration [37] .…”