Elspeth H. Whitby

Frequency and natural history of subdural haemorrhages in babies and relation to obstetric factors

BACKGROUND Subdural haematomas are thought to be uncommon in babies born at term. This view is mainly based on findings in symptomatic neonates and babies in whom subdural haemorrhages are detected fortuitously. We aimed to establish the frequency of subdural haemorrhages in asymptomatic term neonates; to study the natural history of such subdural haematomas; and to ascertain which obstetric factors, if any, are associated with presence of subdural haematoma. METHODS We did a prospective study in babies who were born in the Jessop wing of the Central Sheffield University Hospitals between March, 2001, and November, 2002. We scanned neonates with a 0.2 T magnetic resonance machine. FINDINGS 111 babies underwent MRI in this study. 49 were born by normal vertex delivery without instrumentation, 25 by caesarean section, four with forceps, 13 ventouse, 18 failed ventouse leading to forceps, one failed ventouse leading to caesarean section, and one failed forceps leading to caesarean section. Nine babies had subdural haemorrhages: three were normal vaginal deliveries (risk 6.1%), five were delivered by forceps after an attempted ventouse delivery (27.8%), and one had a traumatic ventouse delivery (7.7%). All babies with subdural haemorrhage were assessed clinically but no intervention was needed. All were rescanned at 4 weeks and haematomas had completely resolved. INTERPRETATION Presence of unilateral and bilateral subdural haemorrhage is not necessarily indicative of excessive birth trauma.

Comparison of ultrasound and magnetic resonance imaging in 100 singleton pregnancies with suspected brain abnormalities

Objective  To compare the diagnostic accuracy of the current reference standard‐ultrasound with in utero magnetic resonance imaging, in a selected group of patients.

Post-mortem MRI as an adjunct to fetal or neonatal autopsy

CONTEXT Understanding what was wrong with a dead fetus or why a newborn child died can help the parents to grieve, while any findings can be used to inform the parents if there is a risk to future pregnancies and the level of risk. This information is mainly obtained from autopsies, but the number of parents agreeing to autopsy has dropped, which has prompted the search for adjuncts to autopsy. STARTING POINT The UKs Chief Medical Officer outlined the rationale for exploring alternatives to autopsy in 2000 and 2001. After wide consultation, MRI was deemed to offer the most realistic chance of making a contribution. Results so far are promising, but of insufficient depth and quality to make firm recommendations about providing a service in the future. In 2004, the UK Department of Health therefore tendered for this research to be done in fetal and neonatal (and adult) cases, and this work is due to start in 2005. WHERE NEXT? High-quality anatomical information about the brain and spine of fetuses and neonates can be easily obtained with standard MRI scanners. Most developmental and acquired abnormalities can be seen on post-mortem MRI. More work needs to be done on organs not in the central nervous system, and heart malformations, in particular, might present diagnostic problems. A possible outcome could be whole-body MRI plus targeted biopsies of abnormalities taken under image guidance as an adjunct to formal autopsy.

A Prospective Study of Fetuses with Isolated Ventriculomegaly Investigated by Antenatal Sonography and In Utero MR Imaging

BACKGROUND AND PURPOSE: Fetal ventriculomegaly (VM) is important because of its high prevalence and high risk of association with other brain abnormalities. The purpose of this article was to investigate the hypotheses that including in utero MR imaging (iuMR) in the diagnostic pathway for fetuses with isolated VM on antenatal imaging will show other brain abnormalities in a high proportion of cases and that these will have a significant effect on clinical management. MATERIALS AND METHODS: One hundred forty-seven pregnant women were recruited prospectively from 8 fetomaternal centers in Britain. All of the fetuses had VM diagnosed on sonography but no other abnormality. iuMR was performed, and the results of the examinations were compared with those of sonography. Two fetomaternal experts made independent assessments of the effects of any new diagnoses on clinical management. RESULTS: Categoric assessments of ventricular size were the same in approximately 90% of fetuses. Other abnormalities were shown in 17% of fetuses. The most frequent additional brain abnormality shown on iuMR was agenesis of the corpus callosum. Severe VM was associated with an approximately 10-fold increase in the risk of another brain abnormality being present when compared with fetuses with mild VM. The most profound effects on clinical management, however, were found in cases of mild VM. CONCLUSIONS: This work supports our hypotheses by showing a high detection rate of other brain pathology when iuMR was used to supplement antenatal sonography (17%). In a high proportion of cases, the detection of the extra pathology would have led to significant changes in clinical management.

Less Invasive Autopsy: Benefits and Limitations of the Use of Magnetic Resonance Imaging in the Perinatal Postmortem

The decline in the postmortem (PM) autopsy rate in the United Kingdom paralleled the change in public perception of this procedure after the organ retention crisis in 2000. The introduction of magnetic resonance imaging (MRI) in the fetal, perinatal, and pediatric autopsy led some investigators to propose that MRI could replace the conventional PM. We assessed the role of MRI in fetal autopsy as an addition or a potential replacement method to the conventional PM and to evaluate the benefits and limitations of each technique. We retrospectively reviewed the PM and MRI examination of 100 fetuses. The MRI was limited to the brain or brain and spinal cord. Forty-six cases involved termination of pregnancy; 30 were intrauterine fetal deaths/stillbirths; 16 were premature deliveries followed by neonatal death; and 8 were miscarriages. The mean gestational age of all cases was 25.54 weeks (range: 13–41 weeks). In 54 of the 90 full PMs, there was a complete agreement between the MRI and autopsy findings on the morphology of the brain and spine. Despite this agreement, the information gained at the PM was relevant to find the cause or mechanism of death in 20 of 54 cases (37%). In 24 autopsies the MRI added valuable information to the autopsy. However, if MRI had been the only investigation, essential information would have been lost in 17 of 24 cases (71%). In 12 cases the PM was clearly superior to the MRI. The integrated result obtained from the traditional autopsy remains crucial in determining the cause or mechanism of the malformation or of the fetal/perinatal death and accordingly is important for the counseling offered to parents regarding the recurrence risk for future pregnancies.

Ultrafast magnetic resonance imaging of central nervous system abnormalities in utero in the second and third trimester of pregnancy: comparison with ultrasound

Objective To assess the ability of ultrafast magnetic resonance imaging to visualise abnormalities in the central nervous system of third trimester fetuses in utero and to compare the results with the current ‘reference standard’ of ultrasound and postnatal imaging or post‐mortem data.

Investigating direct detection of axon firing in the adult human optic nerve using MRI.

The aim of this study was to directly detect spectral components of the magnetic fields of ionic currents caused by firing of the axons in the optic nerve in response to visual strobe stimulation. The magnetic field parallel to the main B0 field can potentially alter the local phase and magnitude of the MR signal which can cause signal loss due to intravoxel dephasing. Measured frequency spectra showed evidence of the strobe stimulus localized to regions containing the optic nerve, not thought to be due to motion artifacts, in 30 out of 52 experiments in 5 adult human subjects. The effect was (0.15 +/- 0.05)% of the mean magnitude equilibrium signal from the voxel in the frequency range 0.7-3.3 Hz, corresponding to an estimated field of (1.2 +/- 0.4) nT, at an echo time of TE = 32.4 ms using a 1.5 T MRI scanner. Only 1 of 12 phase image experiments showed effects. These findings provide preliminary evidence for direct detection of axonal firing in the optic nerve.

Imaging the fetal spine using in utero MR: diagnostic accuracy and impact on management

BackgroundIn-utero MR imaging (iuMR) has entered the clinical arena during the last decade. It is used mainly for imaging fetal brain abnormalities.ObjectiveTo report our experience of imaging the fetal spine and spinal cord in fetuses with known or suspected abnormalities diagnosed on US imaging.Materials and methodsProspective imaging and retrospective analysis of the possible impact on management of 50 consecutive fetuses with spinal abnormalities detected by antenatal US imaging.ResultsIn 40 (80%) of 50 fetuses, iuMR and US imaging were in complete agreement. In the other 10 fetuses (20%), iuMR provided additional information or changed the diagnosis, including 8 fetuses where the iuMR could find no abnormality and was found to be correct by later follow-up.ConclusionIuMR is useful in fetuses with a suspected spinal abnormality. The clinical impact of iuMR may be numerically less than with brain abnormalities, but is still sufficient to warrant its use, especially if there is any uncertainty about the US imaging, and particularly as a relatively high proportion of diagnoses on US imaging are false-positives.

Low field strength magnetic resonance imaging of the neonatal brain

Background: Magnetic resonance (MR) imaging of the neonate has been restricted by the need to transport the sick baby to the large magnetic resonance scanners and often the need for sedation or anaesthesia in order to obtain good quality images. Ultrasound is the reference standard for neonatal imaging. Objective: To establish a dedicated neonatal MR system and compare the clinical usefulness of MR imaging with ultrasound imaging. Design: Prospective double blind trial. Setting: Neonatal intensive care unit, Sheffield. Main outcome measures: Imaging reports. Patients: 134 premature and term babies. Results: In 56% of infants with pathology suspected on clinical grounds, MR provided additional useful clinical information over and above that obtained with ultrasound. Conclusion: Infants can be safely imaged by dedicated low field magnetic resonance on the neonatal intensive care unit without the need for sedation at a cost equivalent to ultrasound.

Diffusion‐weighted imaging of cerebral white matter and the cerebellum following preterm birth

Aim  The aim of this study was to determine if apparent diffusion coefficients (ADCs) generated with diffusion‐weighted imaging of cerebral white matter and the cerebellum are affected by white matter damage.