Liver acoustic radiation force impulse (ARFI) in childhood obesity: comparison and correlation with biochemical markers.

PURPOSE: To compare and correlate the diagnostic efficiency of acoustic radiation force impulse (ARFI) elastography with biochemical markers for assessing hepatic changes in overweight and obese children.

METHODS: This prospective study was approved by the institutional ethics committee. It included 54 overweight and obese children and 50 normal children (as a control group) in the age range 5-18 years. For all children, we performed grayscale ultrasonography to diagnose fatty liver, ARFI elastography to measure liver stiffness, and biochemical evaluation for aspartate aminotransferase (AST), alanine aminotransferase (ALT), and serum triglyceride (TG) levels.

RESULTS: Of the 54 obese children, AST was elevated in 13 (24.1%) and ALT was elevated in 16 (29.6%); however, only 4 (25%) of these 16 obese children with abnormal aminotransferase levels had an AST/ALT ratio >0.8. Furthermore, all children with abnormal aminotransferase levels with AST/ALT ratio >0.8 also had abnormal readings of ARFI elastography. The TG was elevated (>150 mg/dL) in 2 out of 54 (3.7%) obese children. None of the normal children showed abnormal levels of aminotransferase and TG. Three out of 54 (5.6%) obese children did not show fatty liver changes, while 29 (53.7%) showed grade-I fatty liver changes, and 22 (40.7%) showed grade-II fatty liver changes. The mean (SD) ARFI value was 1.13 m/s (SD 0.199) for obese children and 1.02 m/s (SD 0.11) for children in the control group. Of the 54 obese children, 49 (90.7%) showed ARFI values of <1.19 m/s (normal), 4 (7.4%) had ARFI values from >1.19 to <1.75 m/s, and 1 (1.9%) had an ARFI value >1.75 m/s. Four children with an increased ARFI value also had an AST/ALT ratio >0.8. However, one obese child with a raised ARFI value did not have an elevated AST/ALT ratio, and none of his aminotransferase levels were abnormal. All normal children had ARFI values <1.19 m/s.

CONCLUSION: ARFI elastography shows excellent correlation with AST/ALT ratios in obese children and may be used as a noninvasive tool to detect nonalcoholic fatty liver disease (NAFLD) and associated hepatic changes, especially in pediatric patients, for whom liver biopsy is not always feasible.