Anthony R Hart

Magnetic Resonance Imaging and Developmental Outcome Following Preterm Birth: Review of Current Evidence.

Preterm birth is associated with an increased risk of developmental difficulties. Magnetic resonance imaging (MRI) is increasingly being used to identify damage to the brain following preterm birth. It is hoped this information will aid prognostication and identify neonates who would benefit from early therapeutic intervention. Cystic periventricular white matter damage has traditionally been associated with abnormal motor developmental and cerebral palsy, but its presence on MRI does not preclude normal cognitive development. This has led to increasing interest in the identification of diffuse periventricular white matter damage with conventional and sophisticated MRI. However, the correlation between these appearances and developmental outcome remains unclear. Measurements of the size, volumes, and growth rates of many regions of the brain, such as the corpus callosum, ventricular system, cortex, deep grey matter, and cerebellum, are all also altered following preterm birth, but there is insufficient evidence to use this data in the clinical setting. This article is a review of the current evidence on MRI and developmental outcome, suggesting possible indications for the use of MRI following preterm birth.

Neonatal Cochlear Function: Measurement after Exposure to Acoustic Noise during in Utero MR Imaging

PURPOSE To establish whether fetal exposure to the operating noise of 1.5-T magnetic resonance (MR) imaging is associated with cochlear injury and subsequent hearing loss in neonates. MATERIALS AND METHODS The study was performed with local research ethics committee approval and written informed parental consent. Neonatal hearing test results, including otoacoustic emission (OAE) data, were sought for all neonates delivered in Sheffield who had previously undergone in utero MR imaging between August 1999 and September 2007. The prevalence of hearing impairment in these neonates was determined, with corresponding 95% confidence intervals calculated by using the binomial exact method, and mean OAE measurements were compared with anonymized local audiometric reference data by using the t test. RESULTS One hundred three neonates who had undergone in utero MR imaging were identified; 96 of them had completed hearing screening assessment. Thirty-four of these babies were admitted to the neonatal intensive care unit (NICU), and one of them had bilateral hearing impairment. The prevalence of hearing impairment was 1% (one of 96; 95% confidence interval: 0.03%, 5.67%), which is in accordance with the prevalence expected, given the high proportion of babies in this study who had been in the NICU (ie, NICU graduates). In addition, for the well babies, there was no significant difference in mean OAE cochlear response compared with that for a reference data set of more than 16,000 OAE results. When NICU graduates were included in the comparison, a significant difference (P = .002) was found in one of four frequency bands used to analyze the cochlear response; however, this difference was small compared with the normal variation in OAE measurements. CONCLUSION The findings in this study provide some evidence that exposure of the fetus to 1.5-T MR imaging during the second and third trimesters of pregnancy is not associated with an increased risk of substantial neonatal hearing impairment.

Appearances of diffuse excessive high signal intensity (DEHSI) on MR imaging following preterm birth.

BackgroundDiffuse damage to the periventricular white matter has recently been suggested to be a cause of the cognitive deficits seen following preterm birth. It is unclear whether this form of injury can be visualised on MR imaging, but one group has described diffuse excessive high signal intensity (DEHSI) as a possible form of diffuse white matter injury. This finding is dependant on window imaging and the subjective assessment of the reviewer, but little data have been published on the degree of subjectivity on its appearance among raters.ObjectiveTo assess the subjectivity of DEHSI on conventional and ultrafast T2-weighted MR imaging following preterm birth.Materials and methodsAn observational study of 40 preterm infants who had MR imaging of the brain around term-equivalent age, including conventional fast spin-echo (FSE) and ultrafast single-shot fast spin-echo (SSFSE) T2-weighted sequences in the axial plane. Images were anonymised and scored twice by four observers for the presence of DEHSI. Inter- and intra-observer agreement were calculated.ResultsSixty-five percent of conventional and 100% of the ultrafast images were of diagnostic quality. DEHSI was noted in between 0% and 69.2% of conventional images and 27.5–90% of the ultrafast images. Inter- and intra-observer agreement ranged from none to moderate.ConclusionThe visual appearances of DEHSI on conventional FSE and ultrafast SSFSE T2-W images are highly subjective, limiting its clinical application.

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.

Management and investigation of neonatal encephalopathy: 2017 update

This review discusses an approach to determining the cause of neonatal encephalopathy, as well as current evidence on resuscitation and subsequent management of hypoxic-ischaemic encephalopathy (HIE). Encephalopathy in neonates can be due to varied aetiologies in addition to hypoxic-ischaemia. A combination of careful history, examination and the judicious use of investigations can help determine the cause. Over the last 7 years, infants with moderate to severe HIE have benefited from the introduction of routine therapeutic hypothermia; the number needed to treat for an additional beneficial outcome is 7 (95% CI 5 to 10). More recent research has focused on optimal resuscitation practices for babies with cardiorespiratory depression, such as delayed cord clamping after establishment of ventilation and resuscitation in air. Around a quarter of infants with asystole at 10 min after birth who are subsequently cooled have normal outcomes, suggesting that individualised decision making on stopping resuscitation is needed, based on access to intensive treatment unit and early cooling. The full benefit of cooling appears to have been exploited in our current treatment protocols of 72 hours at 33.5°C; deeper and longer cooling showed adverse outcome. The challenge over the next 5–10 years will be to assess which adjunct therapies are safe and optimise hypothermic brain protection in phase I and phase II trials. Optimal care may require tailoring treatments according to gender, genetic risk, injury severity and inflammatory status.

3D Reconstructions of the Cerebral Ventricles and Volume Quantification in Children with Brain Malformations

RATIONALE AND OBJECTIVES The aim of this study was to assess the ability of a semiautomated process to produce three-dimensional reconstructions of the ventricles and calculate ventricular volumes from magnetic resonance (MR) imaging data in children with structural brain abnormalities. MATERIALS AND METHODS Fourteen children referred for MR imaging of the brain for neurologic symptoms were selected. Seven participants had structural brain abnormalities on MR imaging; seven further participants were age-matched controls with normal brain morphology. MR imaging included T1-weighted volumetric images in all cases. Semiautomated postprocessing techniques were performed on the MR imaging data to generate three-dimensional reconstructions of the ventricles. These were analyzed for morphologic changes, and volumes were calculated. Inter- and intrarater agreement of ventricular volumes were calculated. RESULTS This technique produced detailed three-dimensional reconstructions of the ventricles, even in children with grossly abnormal ventricular morphology. All MR imaging data were successfully postprocessed in <5 minutes. Inter- and intrarater reliability was excellent, with correlation coefficients of 0.99 and 0.92, respectively. CONCLUSION This methodology can create detailed three-dimensional visualizations and volumetric measurements of morphologically abnormal ventricles. This technique could help physicians and parents comprehend abnormal ventricular anatomy better and may have future clinical uses in monitoring disease progression or neurosurgical planning.

Profound encephalopathy with complete recovery in three children with familial hemiplegic migraine.

We describe three cousins who presented with agitation, dysphasia and/or coma, and developed hemiplegia following initial onset of symptoms. Two cases followed minor head injuries, two were pyrexial and two were associated with neutrophilia. Two cases required ventilatory support on the intensive care unit. Magnetic resonance imaging in all three cases showed cortical swelling, and one had evidence of restricted water diffusion on diffusion‐weighted imaging, suggestive of ischaemia/infarction. A complete family history at the time of presentation would have led to an earlier diagnosis of profound encephalopathy in familial hemiplegic migraine, which would have enabled better prognostication of their clinical course and caused less distress for the families.

An MR-compatible neonatal incubator

OBJECTIVES To develop a neonatal MR-compatible incubator for transporting babies between a neonatal intensive care unit and an MRI unit that is within the same hospital but geographically separate. METHODS The system was strapped to a standard MR-compatible patient trolley, which provides space for resuscitation outside the incubator. A constant-temperature exothermic heat pad was used to maintain temperature together with a logging fluoro-optic temperature monitor and alarm system. The system has been designed to accommodate standard knee-sized coils from the major MR manufacturers. The original incubator was constructed from carbon fibre, but this required modification to prevent radiofrequency shading artefacts due to the conducting properties of the carbon fibre. A high-tensile polyester material was used, which combined light weight with high impact strength. The system could be moved onto the patient bed with the coils and infant in place by one technologist. RESULTS Studies in eight neonatal patients produced high quality 1.5 T MR images with low motion artefacts. The incubator should also be compatible with imaging in 3 T MR systems, although further work is required to establish this. Images were acquired using both rapid and high-resolution sequences, including three-dimensional volumes, proton spectra and diffusion weighting. CONCLUSION The incubator provides a safe, quiet environment for neonates during transport and imaging, at low cost.

Destructive encephalopathy in incontinentia pigmenti

Anthony R Hart MRCPCH, Christopher Edwards MBCHB, Jugnu Mahajan MD FRCPCH, Margaret L Wood FRCP, Paul D Griffiths PHD FRCR 1 Sheffield Childrens Hospital NHS Foundation Trust, Western Bank, Sheffield U.K. 2 Department of Paediatrics, Rotherham District General NHS Foundation Trust, Rotherham. 3 Department of Dermatology, Rotherham District General NHS Foundation Trust, Rotherham, UK. 4 Academic Unit of Radiology, University of Sheffield, Sheffield, UK. Correspondence to: t.hart@doctors.org.uk Pubilshed online 28 November 2008.

The use of MR imaging and spectroscopy of the brain in children investigated for developmental delay: What is the most appropriate imaging strategy?

ObjectivesDevelopmental delay is a common problem in paediatric practice and many children with developmental delay are referred for MR imaging. Our study was performed as part of a continuing audit process to optimise our MR protocol and case selection.Materials and methodsWe performed MR imaging and spectroscopy protocol on 157 children with developmental delay. We analysed the effect of these interventions by looking at the overall detection rate of relevant pathology and in particular subgroups of the children.Results71% of the children had normal MR imaging, 10% had non-specific findings and 19% had specific abnormalities on MR imaging. The overall risk of having a specific structural abnormality with isolated developmental was 7.5% but if other neurological symptoms/signs were present the risk was 28%. Two children had abnormal spectroscopic findings, one with tuberous sclerosis and the other with absent brain creatine.ConclusionCase selection for MR imaging is important in children with developmental delay. The best strategies for selecting children for MR are either; not performing MR with developmental delay in one domain only or performing MR with developmental delay in three or four domains or if there are other neurological features.