Yang Shin Park MD, Presenter: Nothing to Disclose

Seong Ho Park MD, Abstract Co-Author: Research Consultant, Infinitt Co, Ltd

Seung Soo Lee MD, Abstract Co-Author: Nothing to Disclose

Sung Gyu Lee MD, Abstract Co-Author: Nothing to Disclose

Eun Sil Yu MD, Abstract Co-Author: Nothing to Disclose

The attenuation difference between the liver and the spleen on unenhanced CT (CTL-S) is a commonly used parameter to estimate hepatic steatosis (HS). However, ironically, there has been no systematic pathology-correlated study about the reference interval of CTL-S. The purpose of this prospective study was to establish the reference interval of CTL-S using same-day hepatic biopsy as the reference standard and to determine its implications in the diagnosis of HS.

A group of 333 healthy hepatic donor candidates (M:F=219:114; mean age±SD=31.5 years±10.0) underwent unenhanced CT of the liver using Lightspeed 16 (GE Healthcare) (n=154) or Somatom Definition (Siemens Medical Solutions) (n=179) with similar scan parameters and subsequently received US-guided liver biopsy on the same day. CTL-S was obtained using region-of-interest measurements. The degree of HS (%) and hemosiderin deposition were determined by pathologic analysis. The effect of CT scanner, gender, and hemosiderin on CTL-S was evaluated using the multiple linear regression analysis. The reference interval of CTL-S was determined by taking the central 95% of the pathology-proven HS-free patients and by calculating the 90% confidence intervals (CIs) of the upper and lower reference limits according to the Clinical and Laboratory Standards Institute Guideline (C28-A3). The sensitivity of the reference interval in the diagnosis of clinically-relevant (≥5%) and moderate (≥30%) degrees of HS was determined.

Significant correlation was found between CTL-S and the pathologic degree of HS (r=0.74; P<.0005). CT scanner and gender were not significantly correlated with CTL-S (P≥.071), whereas hemosiderin was (P=.004). The reference interval for CTL-S was obtained in the 102 patients (M:F=51:51) without HS and ranged from 2 HU (90% CI, 0-3 HU) to 18 HU (90% CI, 16-19 HU). When CTL-S value less than 2 HU was used to define HS on CT, CT showed sensitivity of 21.3% (35/164) and 68.3% (28/41) for the diagnosis of HS≥5% and HS≥30%, respectively.

The pathology-correlated reference interval of CTL-S is 2-18 HU and the suggested criterion of CTL-S to diagnose HS on CT is less than 2 HU.

The diagnosis of HS on unenhanced CT can be made more consistently and scientifically using the reference interval and the proposed criterion.

Park, Y, Park, S, Lee, S, Lee, S, Yu, E, Establishing the Reference Interval of the Attenuation Difference between the Liver and the Spleen on Unenhanced CT Using Same-day Hepatic Biopsy as the Reference Standard.  Radiological Society of North America 2009 Scientific Assembly and Annual Meeting, November 29 - December 4, 2009 ,Chicago IL. http://archive.rsna.org/2009/8011380.html