Effect of skin-capsular distance on controlled attenuation parameter for diagnosing liver steatosis in patients with nonalcoholic fatty liver disease.

The effect of the skin-capsular distance (SCD) on the controlled attenuation parameter (CAP) for diagnosis of liver steatosis in patients with nonalcoholic fatty liver disease (NAFLD) remains unclear. The SCD was measured using B-mode ultrasound, and the CAP was measured using the M probe of FibroScan®. According to the indications of the M probe, 113 patients with an SCD of ≤ 25 mm were included in the present study. The association between the SCD and CAP was investigated, and the diagnostic performance of the SCD-adjusted CAP was tested. The SCD showed the most significant positive correlation with the CAP (ρ = 0.329, p < 0.001). In the multiple regression analysis, the SCD and serum albumin concentration were associated with the CAP, independent of pathological liver steatosis. According to the multivariate analysis, two different formulas were developed to obtain the adjusted CAP using the SCD and serum albumin concentration as follows: adjusted CAP (dB/m) = CAP - (5.26 × SCD) and adjusted CAP (dB/m) = CAP - (5.35 × SCD) - (25.77 × serum albumin concentration). The area under the receiver operating characteristic curve for diagnosis of a steatosis score ≥ 2 of adjusted CAP was 0.678 and 0.684 respectively, which were significantly greater than the original CAP (0.621: p = 0.030 and p = 0.024). The SCD is associated with the CAP independent of liver steatosis. Adjustment of the CAP using the SCD improves the diagnostic performance of the CAP in NAFLD.

Diagnostic Accuracy of FibroScan and Factors Affecting Measurements.

Evaluating liver steatosis and fibrosis is important for patients with non-alcoholic fatty liver disease. Although liver biopsy and pathological assessment is the gold standard for these conditions, this technique has several disadvantages. The evaluation of steatosis and fibrosis using ultrasound B-mode imaging is qualitative and subjective. The liver stiffness measurement (LSM) and controlled attenuation parameter (CAP) determined using FibroScan are the evidence-based non-invasive measures of liver fibrosis and steatosis, respectively. The LSM and CAP measurements are carried out simultaneously, and the median values of more than ten valid measurements are used to quantify liver fibrosis and steatosis. Here, we demonstrate that the reliability of the LSM depends on the interquartile range to median ratio (IQR/Med), but CAP values do not depend on IQR/Med. In addition, the LSM is affected by inflammation, congestion, and cholestasis in addition to fibrosis, while CAP values are affected by the body mass index in addition to steatosis. We also show that the M probe provides higher LSM values but lower CAP values than the XL probe in the same population. However, there was no statistically significant difference between the diagnostic accuracies of the two probes. These findings are important to understand the reliability of FibroScan measurements and the factors influencing measurement values for all patients.