Estudo de precisão diagnóstica da graduação ultrassonográfica da esteatose hepática através da análise de concordância com a densidade tomográfica do fígado

Abstract

Hepatic steatosis (HE) corresponds to the initial phase of Non-Alcoholic Fatty Liver Disease, characterized by deposition of triglycerides in hepatocytes, that is diagnosed by imaging tests. Ultrasonography (US) represents the mainly diagnostic method, it detects the disease and categorizes into three grades (mild, moderate and severe), by the use of qualitative parameters related to increased hepatic echogenicity, a subjective visual assessment of fatty liver. The reliability of this evaluation is frequently questioned among radiologists, as well as described in the literature, which reports intra-observer and inter-observer variability. The objective of the present study was to analyze the precision of US in grading HE, through the exams from patients who had undergone abdominal sonography and computed tomography within a three-month interval between them, which allows the comparison between US grading and liver tomographic density. The level of statistically significant difference was p < 0,01 for density tomographic values in each ultrasound grade, but the median value did not vary significantly when comparing cases of moderate and severe HE (p = 0.718), with a wide overlap in the distribution of density values between these two degrees. Although the US classification is still widely used, it can probably enter the phase of obsolescence and abandonment in the next years, following the technologies life cycle. Magnetic Resonance, elastography and quantitative ultrasound are the most potential technologies to replace conventional US. By considering the fatty liver US classification as a medical device, it shows low levels of effectiveness and efficiency. And it can be related to misleading errors by using a fragile parameter, a bad rule. This study suggests that while this classification remains in daily medical practice, physicians should be encouraged to classify HE not only into the three isolated grades, but also using terms that express doubtful cases, those with borderline appearance, which would be mild/moderate or moderate/severe.