Evaluation of liver tissue by ultrasound elastography and clinical parameters in children with multiple blood cell transfusions.

Abstract

Children receiving multiple blood cell transfusions are prone to iron overload and successive tissue damage in liver parenchyma, making noninvasive screening options desirable. Ultrasound (US) elastography using acoustic radiation force impulse (ARFI) imaging enables evaluation of liver parenchyma stiffness, and MRI allows for quantification of liver iron concentration. The objective was to correlate US elastography with MRI in children who had undergone bone marrow transplantation and to evaluate the modification of liver tissue with US in combination with clinical parameters at follow-up. ARFI, T2*-weighted MRI and a clinical score (HepScore, based on parameters of liver function) were performed in 45 patients (24 male; mean age 9.7years) before and 100days and 365days after transplantation. All received multiple blood transfusions (mean number 22.2 up until 1year after transplantation). We correlated US findings and HepScore with MRI findings. We observed signs of iron accumulation in 29/45 (64.4%) patients on MRI (T2*<10ms) and 15/45 (33.3%) showed increased tissue stiffness (ARFI>5.5kPa). Correlation of elastography and MRI was not significant (P=0.57; n=51 matched measurements). Comparing US elastography with HepScore in receiver operating characteristic (ROC) curve analysis indicated a cut-off for affected parenchyma if HepScore was >5 points (sensitivity 67%, specificity 68%). Simultaneous increases of both indicated tissue alteration. Combining US and HepScore enabled detection of liver tissue alteration through iron overload, but we found no direct significant effect of estimated iron from MRI on ARFI imaging.