Revisão sistemática de estudos de acurácia diagnóstica da ultrassonografia no diagnóstico da esteatose hepática e gordura abdominal em adolescentes

Abstract

With the growing number of overweight adolescents, there was an increase in the prevalence of nonalcoholic fatty liver disease (NAFLD). Consequently, studies with imaging tests involving abdominal fat measurements and hepatic steatosis (HS) were developed and Ultrasonography (US) has been proposed as a non-invasive alternative to computed tomography (CT) and magnetic resonance imaging (MRI). The aim of this study was to perform a systematic review of the literature to identify and synthesize the available evidence on the accuracy of US in the diagnosis of HS and the measurement of abdominal subcutaneous and visceral fat compared to CT and/or MRI. Search in literature was performed in MEDLINE, Cochrane Database of Systematic Reviews, SCOPUS, WEB of SCIENCE, LILACS and ADOLEC databases, without restriction of language, for articles published between january 2000 and september 2015. We selected studies that included obese or overweight adolescents with HS, who underwent US, CT, and/or MRI exams for HS examination and/or abdominal fat measurement. Two independent reviewers selected the articles, with the differences resolved by consulting a third reviewer. No studies involving US accuracy compared to CT and/or MRI were found to measure abdominal fat thickness in this population. We included three US accuracy studies for the detection of HS in adolescents compared to MRI, and two studies also included children. This systematic review found values of sensitivity between 48% and 100%, specificity between 52% and 100%, positive predictive values of US hepatic in children and adolescents between 59 to 100% and statistically significant values of positive likelihood ratio. However, in two studies, the majority of patients (67% and 72%, respectively) with mild steatosis in the US were determined not to have HS by MRI. Thus, these studies would indicate that hepatic US does not have the accuracy needed to classify the degree of steatosis; it is only useful in cases of greater severity of HS and MRI would be considered a more useful and objective method than the US to discriminate differences in liver fat content and for monitoring of young patients with HS, despite its high cost and low availability. Further research on HS diagnosis and abdominal fat measurements involving comparative accuracy studies would be needed to provide a response for future recommendations in this age group.