Postmortem determination of hepatic steatosis. Comparing Rho/Z and fat fraction measurements on dual-energy CT for histological grading: A retrospective analysis

Abstract

Abstract Background Dual-energy computed tomography allows for improved organ characterization by applying two different X-ray energy spectra. Purpose To evaluate the postmortem unenhanced DECT scans of human livers with histologically determined stages of hepatic steatosis; to measure hepatic attenuation, effective atomic number, electron density, fat fraction; to examine whether DECT has an advantage over single-energy CT in distinguishing between steatosis grades. Materials and methods Cases with histologically diagnosed hepatic steatosis were included in this study. Using a standardized DECT scanning protocol, the parameters HU, ρe, Zeff and FF were measured. The diagnostic performance was calculated using the CT-based reference standard of 40HU as the cutoff. In addition, the effect of less strict cutoff values for all measured parameters on diagnostic performance was evaluated. Results 119 cases were included in the study. In histology, mild steatosis was detected in 84 cases, moderate steatosis was detected in 21 cases, and severe steatosis was detected in 14 cases. The reference cutoff value of 40HU led to a high specificity (99%) but limited sensitivity (46%), while the prediction accuracy was 83%. A combination of less strict HU cutoff values with FF improved the sensitivity to 57% and accuracy to 86%. Conclusion This study reported that DECT can improve the diagnostic performance of distinguishing between mild and moderate-to-severe forms of hepatic steatosis by combining HU values with FF. Consequently, DECT is advantageous over single-energy scans.