# Intrauterine blood transfusion causes dose- and time-dependent signal alterations in the liver and the spleen on fetal magnetic resonance imaging

## TL;DR

MRI scans show that life-saving blood transfusions in the womb can cause changes in the liver and spleen of fetuses, including size increases and signal changes linked to iron buildup.

## Contribution

First study to report MRI signal alterations in fetal liver and spleen following intrauterine transfusions.

## Key findings

- Fetuses receiving transfusions had significantly larger liver and spleen volumes.
- T1 signal intensity inversely correlated with the number of transfusions.
- T2 signal intensity strongly correlated with time since last transfusion.

## Abstract

Intrauterine transfusions (IUTs) are a life-saving treatment for fetal anemia. However, with each transfusion, iron bypasses uptake regulation through the placenta and accumulates in fetal organs. Unlike other imaging modalities, fetal magnetic resonance imaging (MRI) is capable of non-invasively assessing fetal liver disease and/or organ iron overload. This study aimed to investigate the effects of IUTs on MRI findings in the fetal liver and spleen.

For this retrospective study, we included eight fetuses undergoing IUT and prenatal MRI from 2014 to 2023. The fetuses were gestational age-matched with a cohort that received fetal MRI for other indications, but no IUTs. Signal intensity (SI) and volumetric analyses of the liver and the spleen were performed.

Fetuses receiving transfusions had significantly larger volumes of both liver (p = 0.003) and spleen (p = 0.029). T1 SI inversely correlated with the number of IUTs (Pearson’s r = −0.43, p = 0.099). This effect regressed over time (r = 0.69, p = 0.057). T2 SI did not correlate significantly with transfusion frequency but showed a strong positive correlation with the number of days between IUT and MRI (r = 0.91, p = 0.002). For splenic SI measures, similar effects were observed regarding T1 SI reduction per received transfusion (r = −0.36, p = 0.167) and recovery of T2 SI after IUT (r = 0.88, p = 0.004).

This is the first study to report the effects of IUTs on MRI data of fetal livers and spleens. We observed considerable dose- and time-dependent SI alterations of the liver and spleen following IUT. Furthermore, fetal hepatosplenomegaly can be expected following IUT.

Question
What fetal changes are found by MRI after life-saving intrauterine transfusion (IUT)?

Findings
Dose- and time-dependent reductions in signal intensity of the fetal liver and spleen, as well as hepatosplenomegaly, were found after intrauterine transfusion.

Clinical relevance
Intrauterine transfusions cause transient iron overload with consequential changes in MRI signal intensity of fetal livers and spleens. Fetal hepatosplenomegaly can be expected following transfusions. Radiologists’ awareness of changes following IUT may improve report quality.