Non-Invasive Diagnostic Tests for MASLD in Pediatric Population

Non-Alcoholic Fatty Liver Disease (NAFLD) is currently the leading cause of liver disease in children. The name of NAFLD recently changed to metabolic dysfunction associated steatotic liver disease (MASLD). The definition of MASLD is the presence of steatosis in the liver and a metabolic abnormality, in the setting of other liver steatotic liver diseases having been ruled out. Due to its association with obesity and diabetes, MASLD prevalence is rising worldwide following the upward trends of these diseases. Among the United States pediatric population, the prevalence of NAFLD has been measured at around 11% and it varies widely among races. MASLD is likely very similar in numbers. Because of the natural history of the disease, MASLD patients are at risk of developing cardiovascular complications and hepatocellular carcinoma, raising the issue of diagnosing and treating promptly with the most accurate approaches.

Liver biopsy is the gold standard for assessing inflammation and fibrosis in metabolic dysfunction associated steatotic liver disease. This test is highly sensitive and specific, however some weaknesses exist. Liver biopsy uses a small sample size which can misrepresent the overall health/disease of the organ and there can be interpretation variability within the pathologists assessing the histology. Liver biopsy is also an invasive test, making it less desirable due to the potential of complications and cost. Due to these and despite being the most exact test, its invasive nature and its high price, make it not widely used.

There are several clinical needs, including a better way to rapidly diagnose MASLD in the outpatient clinic setting and to measure the severity of MASLD in patients already diagnosed. The first need, to diagnose MASLD requires demonstrating the presence of steatosis through imaging and sending some standard labs to rule out other conditions and assess metabolic features. The second need focuses primarily on fibrosis assessment, because the amount of fibrosis is the most closely associated with long term outcomes. While inflammation quantity is also important for staging MASLD, inflammation tends to rise and fall with changes in lifestyle and presents a less durable finding. Currently, in pediatrics the level of inflammatory injury is reasonably well represented by change in alanine transaminase (ALT). Thus, validating it is not a primary or secondary objective in this proposal.

The most accurate non-invasive imagining diagnostic test for hepatic steatosis in MASLD is Magnetic Resonance Imagining (MRI) and Magnetic Resonance Spectroscopy (MRS). Specifically, the MRI with Proton Density Fat Fraction (PDFF), has shown to have the best results at diagnosing liver steatosis since it is able to map for fat to the whole liver. Accurate fibrosis assessments have been accomplished with the use of Magnetic Resonance Elastography (MRE) and possess an advantage over ultrasound fibrosis measurements because it is independent of abdominal fat. In spite of that, this imaging is not widely available, and it is still highly priced making it less available.