Changes in Liver Shear Wave Elastography of Preterm Infants during Hospitalization

Abstract

Liver evaluation is essential in preterm infants because of exposure to hepatotoxic drugs, the effects of parenteral nutrition, and their organ immaturity. The clinical significance of shear wave elastography (SWE) which measures tissue elasticity, is unclear in preterm infants. For SWE application to liver evaluation in preterm infants, we examined the postnatal course and factors associated with changes.We prospectively measured liver SWE values every other week in 37 preterm infants born at 23 to 35 weeks gestation and 12 term infants born after 36 weeks gestation.The median early postnatal liver SWE value was 1.22 (interquartile range, 1.19-1.26) m/s. The correlations of liver SWE values with gestational age and birth weight were r = -0.18 (p = 0.23) and r = -0.21 (p = 0.157), respectively. The median liver SWE values from birth to 36 to 38 postmenopausal weeks were 1.22 (1.17-1.24) m/s at <28 weeks gestation (n = 9), 1.21 (1.18-1.25) m/s at 28 to 29 weeks gestation (n = 11), 1.24 (1.21-1.28) m/s at 30 to 31 weeks gestation (n = 8), and 1.21 (1.20-1.24) m/s at ≥32 weeks gestation (n = 9). There was no change over time in any gestational age group (p = 0.158). The median liver SWE values were 1.22 (1.17-1.25) m/s (n = 10) and 1.22 (1.19-1.25) m/s (n = 27) for small- and appropriate-for-gestational-age infants, respectively (p = 0.93). The correlations of abnormally high serum concentrations of direct bilirubin (>1.0 mg/dL) and alanine aminotransferase (>12 IU/L) with liver SWE values were r = 0.37 (p = 0.041) and r = 0.21 (p = 0.35), respectively.Liver SWE values may be useful for the evaluation of liver damage with cholestasis in preterm infants because they remain constant regardless of gestational age and birth weight and do not change over time or with a deviation of body size. · Liver SWE was prospectively performed in preterm infants.. · Liver SWE was constant until term regardless of gestational age or birth weight.. · Liver SWE values of preterm infants ranged from 1.2 to 1.3 m/s.. · For preterm infants, elevation of liver SWE values reflected cholestasis.. · Liver SWE may become the new standard for liver evaluation in preterm infants..

Fig. 1

Correlation between liver shear wave elastography (SWE) values in the early postnatal period and perinatal data. Scatter plots show the correlation between the early postnatal liver SWE values and the perinatal information. ( A ) Gestational age: r  = −0.18 ( p  = 0.23). ( B ) Birth weight: r  = −0.21 ( p  = 0.157).

Fig. 2

Correlation between liver shear wave elastography values and laboratory data. Scatter plots show the correlation between the liver shear wave elastography values and the maximum serum direct bilirubin and alanine aminotransferase concentrations. ( A ) Maximum serum direct bilirubin concentrations of the infants in whom the serum direct bilirubin concentration was >1.0 mg/dL, defined as direct hyperbilirubinemia ( n  = 30): r  = 0.37 ( p  = 0.041). ( B ) Maximum serum alanine aminotransferase concentrations of the infants in whom the serum alanine aminotransferase concentration was >12 IU/L, which is the upper limit of normal for preterm infants ( n  = 22): r  = 0.21 ( p  = 0.35).

Fig. 3

Time course of liver shear wave elastography values in infants with cholestasis. ( A ) A boy born at 23 weeks of gestation, 450 g, underwent colostomy because of necrotizing enterocolitis at 3 weeks after birth. He required prolonged parenteral nutrition and subsequently developed intestinal failure-related liver disease. ( B ) A boy born at 24 weeks of gestation, 544 g, digested enteral feeding (mother's milk) well, and parenteral nutrition was terminated 2 weeks after birth. However, when feeding with milk formula was started 5 weeks after birth, he developed a gastrointestinal allergy, and parenteral nutrition was resumed. He thereafter required prolonged parenteral nutrition and subsequently developed intestinal failure-related liver disease. ( C ) A boy born at 30 weeks of gestation, 839 g, had poor digestion on enteral feeding; therefore, parenteral nutrition was continued until 4 weeks after birth. He developed intestinal failure-related liver disease 4 weeks after birth because of persistent indigestion associated with gastrointestinal allergy, which resolved spontaneously 6 weeks after birth. All infants were discharged from the hospital alive.