The Accuracy of Ultrasound Controlled Attenuation Parameter in Diagnosing Hepatic Fat Content

Sebastiana Atzori,1,2 Yasmin Pasha,1 James B Maurice,1,3 Simon D Taylor-Robinson,1 Louise Campbell,1,4 Adrian KP Lim1,5 1Department of Surgery and Cancer, Imperial College London, London, W1 1NY, UK; 2Department of Medicine, Sassari University Hospital, Sassari, 07100, Italy; 3UCL Institute for Liver and Digestive Health, Royal Free Hospital Campus, London, NW3 2QG, UK; 4Office of the Clinical Director, Tawazun Health, London, W1G 9QN, UK; 5Department of Imaging, Charing Cross Hospital, Imperial College Healthcare NHS Trust, London, W6 8RF, UKCorrespondence: Sebastiana Atzori, Department of Medicine, Sassari University Hospital, Via Enrico de Nicola, Sassari, 07100, Italy, Tel +39 3483359085, Email sebastiana_atzori@yahoo.itPurpose: The Controlled Attenuation Parameter (CAP score) is based on ultrasonic properties of retropropagated radiofrequency signals acquired by FibroscanTM (Echosens, Paris, France). Since ultrasound propagation is influenced by the presence of fat, CAP score was developed to quantify steatosis. The aim of this study was to delineate the accuracy of CAP in diagnosing hepatic steatosis, compared to the gold standard of liver biopsy.Patients and Methods: A total of 150 patients underwent same-day liver biopsy and measurement of hepatic steatosis with Fibroscan. Only examinations with 10 satisfactory measurements, and an inter-quartile range of less than 30% of the median liver stiffness values were included for data analysis. Histological staging was then correlated with median values and Spearman correlation calculated. P values of < 0.05 were considered statistically significant.Results: For diagnosis of hepatic steatosis (HS), CAP could predict the steatosis S2 with AUROC 0.815 (95% CI 0.741– 0.889), sensitivity (0.81) and specificity (0.73) when the optimal cut-off value was set at 288 dB/m. CAP detected histological grade S3 with AUROC 0.735 (95% CI 0.618– 0.851), sensitivity (0.71) and specificity (0.74), with a cut-off value of 330 dB/m. The AUROC for steatosis grade S1 was 0.741 (95% CI 0.650– 0.824), with a cut-off value of 263 dB/m with sensitivity 0.75 and specificity 0.70. Univariate analysis showed a correlation between CAP and diabetes (p 0.048).Conclusion: The performance of CAP to diagnose steatosis severity decreases as steatosis progresses. CAP is associated with diabetes but not other clinical factors and parameters of the metabolic syndrome.Keywords: fibroscan, steatosis, diabetes, ballooning, liver, fibrosis