Perihepatic Adipose Tissue Thickness: a New Non-Invasive Marker of NAFLD?

Background and Aims: Several non-invasive markers have been proposed to assess liver damage in NAFLD. We measured by ultrasound (US) the perihepatic adipose tissue thickness (PATT), i.e. the thickness of the fat between the abdominal muscular layer and the hepatic surface, in addition to waist circumference, BMI, biochemistry and serum adipokines, to predict the severity of liver damage in NAFLD. Methods: 63 NAFLD patients and 45 controls were studied. PATT and US steatosis score were assessed in all patients. Histology was obtained in those with an US steatosis score >= 2. Results: PATT was 13.5 +/- 4.1 mm in NAFLD vs 8.0 +/- 4.1 in controls (p<0.001). A PATT value of 11.2 mm seems to represent a cut-off below which NAFLD is unlikely. Test sensitivity, specificity and the area under the ROC curve were 100%, 50% and 75%, respectively, suggesting a good discrimination between patients with non-NASH and those with NASH or borderline NASH. In addition, PATT strongly correlated with waist circumference (p<0.001). Both PATT and waist circumference correlated with US steatosis, HOMA-IR, TNF-alpha, 1L-6 and leptin. Based on a multiple logistic regression analysis, waist circumferences >= 110, 113 and 122 cm were associated with a probability >= 50% of abnormal HOMA-IR, TNF-alpha and leptin values, respectively. Conclusion: PATT and waist circumference could represent non-invasive markers predicting the severity of liver damage in NAFLD.