The Fetal Spleen in Low-Risk Pregnancies and prior to Preterm Birth: Observational Study of the Role of Anatomical and Functional Magnetic Resonance Imaging

INTRODUCTION

Spontaneous preterm birth complicates ∼7% of pregnancies and causes morbidity and mortality. Although infection is a common etiology, our understanding of the fetal immune system in vivo is limited. This study aimed to utilize T2-weighted imaging and T2* relaxometry (which is a proxy of tissue oxygenation) of the fetal spleen in uncomplicated pregnancies and in fetuses that were subsequently delivered spontaneously prior to 32 weeks.

METHODS

Women underwent imaging including T2-weighted fetal body images and multi-eco gradient echo single-shot echo planar sequences on a Phillips Achieva 3T system. Previously described postprocessing techniques were applied to obtain T2- and T2*-weighted imaging of the fetal spleen and T2-weighted fetal body volumes.

RESULTS

Among 55 women with uncomplicated pregnancies, an increase in fetal splenic volume, splenic:body volume, and a decrease in splenic T2* signal intensity was demonstrated across gestation. Compared to controls, fetuses who were subsequently delivered prior to 32 weeks' gestation (n = 19) had a larger spleen when controlled for the overall size of the fetus (p = 0.027), but T2* was consistent (p = 0.76).

CONCLUSION

These findings provide evidence of a replicable method of studying the fetal immune system and give novel results on the impact of impending preterm birth on the spleen. While T2* decreases prior to preterm birth in other organs, preservation demonstrated here suggests preferential sparing of the spleen.

Premature birth associated with a favorable course in gestational alloimmune liver disease (GALD): A case report

Gestational alloimmune liver disease (GALD) is a rare neonatal disorder with high mortality and morbidity. The patients come to caregivers' attention aged a few hours or days. The disease manifests as acute liver failure with or without siderosis. The differential diagnosis of neonatal acute liver failure (NALF) is broad, including mainly immunologic, infectious, metabolic and toxic disorders. The most common cause, however, is GALD followed by herpes simplex virus (HSV) infection. The best suited pathophysiological paradigm of GALD is that of a maternofetal alloimmune disorder. State of the art treatment combines intravenously administered immunoglobulin (IVIG) with exchange transfusion (ET). We report an infant born at 35 + 2 weeks' gestation in whom GALD had a favorable course, of interest because premature birth in our patient may have exerted protective aspects and lessened morbidity in that intrauterine exposure to maternal complement-fixing antibodies was shortened. The diagnosis of GALD was challenging and difficult. We suggest a modified diagnostic algorithm combining clinical findings with histopathologic findings in liver and lip mucosa and, if available, on abdominal magnetic resonance imaging-study focusing on the liver, spleen, and pancreas. This diagnostic workup must be followed by ET and subsequent administration of IVIG without delay.

Magnetic resonance imaging of neonatal hemochromatosis

Neonatal hemochromatosis is a rare condition that causes neonatal liver failure, frequently resulting in fetal loss or neonatal death. It is thought that most cases of neonatal hemochromatosis are caused by gestational alloimmune liver disease (GALD), with neonatal hemochromatosis being a phenotype of GALD rather than a disease process. Extrahepatic siderosis in the pancreas, myocardium, thyroid and minor salivary gland is a characteristic feature of neonatal hemochromatosis. There is also sparing of the reticuloendothelial system with no iron deposition in the spleen. Hepatic and extrahepatic siderosis seen in neonatal hemochromatosis is from iron dysregulation secondary to liver damage rather than iron deposition causing the liver damage. The presence of extrahepatic siderosis in the pancreas and thyroid is diagnostic of neonatal hemochromatosis and can be detected noninvasively by multi-echo gradient recalled echo (GRE) T2*-weighted sequence of MRI within hours of birth. This helps to expedite the treatment in the form of intravenous immunoglobulin and exchange transfusion, which improves the survival in these babies. The finding of hepatic siderosis is nonspecific and does not help in the diagnosis of neonatal hemochromatosis because it is seen with other causes of advanced liver disease.

Magnetic Resonance Imaging Findings in Neonatal Hemochromatosis

BACKGROUND

There are limited data on utility of magnetic resonance imaging (MRI) in the assessment of suspected neonatal hemochromatosis (NH).

OBJECTIVES

The aim of the study was to present our experience with utilization of multi-echo sequence MRI technique in the evaluation of NH and to compare MRI findings in infants with and without NH.

METHODS

MRI performed for suspected NH were retrospectively reviewed to note the presence and severity of iron deposition (ID) in liver, spleen, pancreas, and kidneys on multi-echo sequences. Findings were compared in infants with and without NH.

RESULTS

Of 20 infants (9 boys and 11 girls; median age of 12.5 days) included in the study, 7 of 20 had NH and 13 of 20 were assigned to the non-NH group. Higher degree of pancreatic ID was seen in the NH group (P = 0.001) with 4 of 7 evaluable pancreas showing moderate-to-severe degree and 1 of 7 showing mild degree of ID whereas none of the 13 infants in non-NH group showed moderate or severe degree of pancreatic ID. Even though the severity of hepatic ID was higher in NH group (P = 0.033), variable severity of hepatic ID was seen in both groups with most infants in both groups showing moderate-to-severe degree of ID. The severity of splenic ID was not particularly associated with any group (P = 0.774) but there was no moderate or severe degree of ID in NH. Renal ID was seen in two infants in non-NH group.

CONCLUSIONS

A moderate-to-severe degree of pancreatic ID seen on MRI tends to be associated with NH and should be sought to establish a timely diagnosis of NH. Presence and severity of hepatic ID cannot be used for differentiation of NH from other causes of neonatal liver failure.