Evaluation of liver fibrosis with T2 relaxation time in infants with cholestasis: comparison with normal controls

Abstract

The degree of hepatic fibrosis in biliary atresia (BA) correlates with the prognosis of the disease and thus, early diagnosis of liver fibrosis is clinically important. Liver biopsy is the gold standard for the evaluation of liver fibrosis, but it is an invasive procedure requiring sedation in children. Therefore, it is desirable to identify a noninvasive method for diagnosis and follow-up of hepatic fibrosis. The purpose of this study is to evaluate the possibility of quantifying liver fibrosis in infants by T2 relaxation time measurements. The institutional review board approved this prospective study and parental informed consent was obtained. During MR cholangiopancreatography using a 1.5-T MR scanner in infants with neonatal cholestasis, T2 relaxation time of the liver was calculated with the mean signal intensities measured on images obtained using spin-echo sequences (TR/TE, 2,000/20, 40, 60, 80, 100, 120, 140, 160 ms). A normal control study was performed during spinal MRI in infants with anorectal malformation and normal liver enzyme profiles. A liver biopsy was obtained in the children with cholestasis. The correlation between histopathological fibrosis stage and T2 relaxation time was evaluated by Kendall's Tau-b test. Twenty-five infants (male: female, 12:13; age range 0-11 months, mean 3.2 months), 14 with neonatal cholestasis (9 BA and 5 non-BA) and 11 normal controls were included in this study. Relaxation times (mean ± standard deviation [SD]) for the liver were 57.8 ms ± 8.8 in the normal control group (n=11) and 56.8 ms ± 9.6 in the BA group (n=9) without statistically significant differences (P=0.811). T2 relaxation times were not significantly different between the low stage (≤ F1) and high stage (≥ F2) fibrosis (mean 57.8 vs 56.8; P=0.934). T2 relaxation of a normal infant liver at 1.5-T had a mean value of 57.8 ms, which is comparable with adult data (46-57 ms). However, T2 relaxation time was not different in patients with BA and did not correlate with stage of fibrosis.