Desenvolvimento de um Modelo Matemático Preliminar Baseado em Escala de Cinza para Avaliação de Esteatose Hepática: Um Estudo Piloto Unicêntrico

Abstract

Introduction: Echogenicity is a measure used in ultrasound imaging to assess the ability of tissue to reflect sound waves. In the case of hepatic tissue, it is important to identify and classify different levels of echogenicity to assist in diagnosing possible alterations. As ultrasound imaging is operator-dependent, there is a gap in accurately defining the levels of metabolic dysfunction-associated steatohepatitis (MASH). Objective: To develop a mathematical model for estimating levels of echogenicity in hepatic tissue in MASH based on grayscale values. Method: The common number of grayscale levels in an ultrasound is 256. We utilized a dataset containing experimental grayscale values (Ci) and corresponding echogenicity values (Ei). The method of least squares was applied to determine the equations describing the relationship between Ci and Ei. Results: We assume that E is a linear function of the grayscale, given by: E = m x C + b. Where: E = is the unit of measurement of echogenicity, C = is the value of the grayscale (0 to 256), m = is the slope coefficient of the line relating E to C, and b is the intercept coefficient of the line. The results derived from the least squares method provided the following regression equations: m = (Σ(Ci - Cm) x (Ei - Em)) / (Σ(Ci - Cm)^2) and b = Em - m x Cm. These equations allowed us to estimate the levels of echogenicity in hepatic tissue based on grayscale values. Thus, on a grayscale ranging from 0 to 256, hepatic tissue with normal echogenicity presented a value within the range of 120 to 150; mild hepatic steatosis demonstrated values between 150 and 180; moderate MASH had a value between 180 and 210; severe MASH had a value above 210. Conclusion: The regression equations obtained through the method of least squares can be used to calculate the degrees of MASH. This estimation can assist in the diagnosis and monitoring of hepatic tissue alterations in ultrasound examinations.