Imaging of the brain in full-term neonates: does sonography still play a role?

State-of-the-art cranial ultrasound in clinical scenarios for infants born at term and near-term

Neonates admitted to the intensive care unit are at risk of brain injury. Importantly, infants with signs of neurological impairment need prompt diagnosis to guide intervention. Cranial ultrasound (CUS) is the first-line imaging tool for infants born preterm. New developments in this technology, which now incorporates high-resolution equipment, have notably improved the performance of CUS in infants born at term and near-term. On the other hand, the potential of CUS as a diagnostic tool in older infants is less established. The lack of studies focusing on this topic, local protocol variability among clinical sites, and divergent opinions on CUS patterns of disease entities are the main constraints. This review provides an overview of state-of-the-art CUS as a decision-making tool under different clinical scenarios, such as neonatal encephalopathy, seizures, and suspected central nervous system infection. The CUS features that characterize several patterns supporting a diagnosis are detailed, focusing on haemorrhage and infection.

Feasibility of Brain Ultrasound Performed by Nurses in the Evaluation of Newborns Who Are HIV Exposed in Utero and Uninfected: A Pilot Study in Botswana

BACKGROUND

Children who are exposed to HIV in utero but are uninfected (HIV-exposed uninfected or HEU) are at higher risk of neurodevelopmental delays compared to children born to persons without HIV. Magnetic resonance imaging (MRI) studies have revealed differences in grey matter volumes, cerebral perfusion, and white matter changes in these children. However, MRI is costly and not widely available in areas with high HIV prevalence, like Botswana, where more than 15% of children are HEU. To address this, we explored the use of brain ultrasound, conducted by trained study nurses, as a safe, less costly, and accurate alternative method for assessing differences relating to HIV exposure status in the brain structures of neonates.

METHODS

Brain ultrasounds of newborns in the Following Longitudinal Outcomes to Understand, Report, Intervene and Sustain Health for Infants, Children, Adolescents who are HIV Exposed Uninfected (FLOURISH) observational study-comprising 35 HEU newborns and 24 HIV-unexposed (HU) newborns-were performed by study nurses and evaluated by a pediatric radiologist for quality and structural abnormalities, such as calcifications, cysts, and hemorrhages. Two radiologists measured extra-axial cerebrospinal fluid spaces, ventricles, and the corpus callosum.

RESULTS

Ultrasound studies of 59 newborns (59% boys; median gestational age 38.4 weeks) were completed. All studies were of diagnostic quality, with 90.2% rated as being of good or excellent quality. Structural abnormalities were rare (10.2% incidence) and did not differ by HIV exposure group. Corpus callosum length was shorter in HEU infants compared to HU infants (45.7 mm vs. 47.3 mm; p = 0.03). Other ventricular and corpus callosum measurements showed no significant variations.

CONCLUSIONS

Brain ultrasounds conducted by study nurses are feasible and reveal differences in corpus callosum length between HEU and HU infants. The benefits of easier training, lower cost, and rapid deployment make ultrasound a promising screening tool in resource-limited settings.

Early Morbidities of Hypoxia-Ischemic Encephalopathy in Term Neonates With a Resistive Index as a Prognostic Indicator

Background Acidosis, hypoxemia, and hypercarbia are symptoms of a syndrome known as perinatal asphyxia that occurs during the first and second stages of labor and shortly after delivery due to poor gas exchange. The Doppler technique is a non-invasive way to assess the risk of neurodevelopment damage in hypoxic-ischemic encephalopathy (HIE) that may be done at the patient's bedside without disturbing them. The study aims to evaluate cranial ultrasound findings in HIE and investigate the role of resistive index (RI) values assessed by color Doppler transcranial ultrasonography in predicting early morbidities in neonates with HIE within 72 hours of life. Methodology Prospective observational research was carried out at the north Karnataka region's tertiary newborn critical care unit. The study included 54 infants with HIE in total. The male-to-female ratio was 1.7:1, with 34 (63%) male and 20 (37%) female newborns. Results About 32 instances had grade I HIE, 8 had grade II HIE, and 14 had grade III HIE. In 35 instances (64.81%), the RI was normal; in 19 cases (35.19%), it was abnormal. Increased periventricular density and cerebral parenchyma echo density were common Doppler ultrasonography findings. Roughly 93% of people survived, and 7% of people died from HIE. Seizures (12.96%) and acute renal damage (33.33%) were the most frequent consequences. Conclusion In instances of HIE, the RI was revealed to be a favorable predictive indicator for newborn prognosis. Counseling and educating parents about early morbidities, anticipated long-term consequences, and the need for follow-up will all benefit from it. Additionally, color Doppler is a practical and secure diagnostic method for determining a newborn's level of HIE.

Quantitative Evaluation of Brain Echogenicity in Hypoxic-Ischemic Encephalopathy in Term Neonates Compared with Controls

Purpose Neurosonography evaluation of neonatal hypoxic-ischemic encephalopathy (HIE) is mainly qualitative. We aimed to quantitatively compare the echogenicity of several brain regions in patients with HIE to healthy controls. Materials and Methods 20 term neonates with clinical/MRI evidence of HIE and 20 term healthy neonates were evaluated. Seven brain regions were assessed [frontal, parietal, occipital, and perirolandic white matter (WM), caudate nucleus head, lentiform nucleus, and thalamus]. The echogenicity of the calvarial bones (bone) and the choroid plexus (CP) was used for ratio calculation. Differences in the ratios were determined between neonates with HIE and controls. Results Ratios were significantly higher for HIE neonates in each region (p<0.05). The differences were greatest for the perirolandic WM, with CP and bone ratios being 0.23 and 0.22 greater, respectively, for the HIE compared to the healthy neonates (p<0.001). The perirolandic WM had a high AUC, at 0.980 for both the CP and bone ratios. The intra-observer reliability for all ratios was high, with the caudate to bone ratio being the lowest at 0.832 and the anterior WM to CP ratio being the highest at 0.992. Conclusion When coupled with internal controls, quantitative neurosonography represents a potential tool to identify early neonatal HIE changes. Larger cohort studies could reveal whether a quantitative approach can discern between degrees of severity of HIE. Future neurosonography protocols should be tailored to evaluate the perirolandic region, which requires posterior coronal scanning.

Imaging of Hypoxic-Ischemic Injury (in the Era of Cooling)

Hypoxic-ischemic injury (HII) is a major worldwide contributor of term neonatal mortality and long-term morbidity. At present, therapeutic hypothermia is the only therapy that has demonstrated efficacy in reducing severe disability or death in infants with moderate to severe encephalopathy. MRI and MRS performed during the first week of life are adequate to assess brain injury and offer prognosis. Patterns of injury will depend on the gestation age of the neonate, as well as the degree of hypotension.

Role of Neurosonography in Critically Ill Neonates in NICU

Background

Neurosonography has been commonly used for screening in neonatal intensive care unit (NICU), for early detection of defects in the central nervous system (CNS) which include findings like intracranial hemorrhage, hydrocephalus, cerebral edema, and other structural abnormalities.

Aim

To detect the CNS abnormality in critically ill neonates by neurosonography.

Materials and Methods

This was a cross-sectional study done in the NICU of AVBR Hospital, Sawangi Meghe, Wardha. Neonates were defined as “critically ill” after taking their detailed history and performing a complete physical examination. Following this, the newborns who fulfilled the studies’ inclusion criteria were subjected to neurosonogram. The following factors were considered: gestational age, clinical examination, investigations, neurosonography findings, and outcomes.

Results

A total of 150 critically ill newborns were subjected to neurosonography, 24 of them had abnormal findings. There was a significant correlation of gestational weeks, mode of delivery, and diagnosis of critically ill neonates with abnormal neurosonography ( P = .000, P = .000, and P = .000). Prematurity was the most common diagnosis followed by meningitis. A total of 16% of the newborns had abnormal results in neurosonography. About 6.67% of these had hydrocephalus, 5.34% had an intraventricular hemorrhage (IVH), 1.34% had periventricular echogenicity, 0.66% had cerebral edema, 0.67% had germinal matrix hemorrhage, and 0.66% had brain abscess. A total of 109 (72.67%) participants in the study had a positive outcome at the time of discharge from NICU; whereas, 27 (18%) unfortunately did not survive.

Conclusion

Neurosonography is thus a valuable, safe, and effective diagnostic tool used for screening critically ill neonates for abnormalities of the brain.

Ultrasound imaging of preterm brain injury: fundamentals and updates

Neurosonography has become an essential tool for diagnosis and serial monitoring of preterm brain injury. Preterm infants are at significantly higher risk of hypoxic-ischemic injury, intraventricular hemorrhage, periventricular leukomalacia and post-hemorrhagic hydrocephalus. Neonatologists have become increasingly dependent on neurosonography to initiate medical and surgical interventions because it can be used at the bedside. While brain MRI is regarded as the gold standard for detecting preterm brain injury, neurosonography offers distinct advantages such as its cost-effectiveness, diagnostic utility and convenience. Neurosonographic signatures associated with poor long-term outcomes shape decisions regarding supportive care, medical or behavioral interventions, and family members' expectations. Within the last decade substantial progress has been made in neurosonography techniques, prompting an updated review of the topic. In addition to the up-to-date summary of neurosonography, this review discusses the potential roles of emerging neurosonography techniques that offer new functional insights into the brain, such as superb microvessel imaging, elastography, three-dimensional ventricular volume assessment, and contrast-enhanced US.

Using Doppler sonography resistive index for the diagnosis of perinatal asphyxia: a multi-centered study

BACKGROUND AND OBJECTIVE

Inhere we evaluated the diagnostic utility of Doppler sonography (DS) of the anterior cerebral artery (ACA), middle cerebral artery (MCA) and the basilar arteries (BA) based on resistive index (RI) for the diagnosis of asphyxia.

METHODS

In this multi-centered cross-sectional study, neonates with clinical diagnosis of asphyxia, were considered for study. During the first 24 h, neonates underwent DS. MRI was done for each neonate during the first month, after discharge or during hospital admission, after obtaining clinical stability. Staging based on DS was compared with staging based on MRI.

RESULTS

Overall, 34 patients entered the study. DS of the ACA, MCA, BA all had significant correlation with MRI findings (regarding severity of asphyxia) (r > 0.8 and p < 0.001). In the receiver-operating-characteristic analysis, ideal cut-off point for diagnoses of asphyxia based on ACA and BA was RI ≤ 0.62 [area under the curve (AUC) = 0.957 and 95% CI: 0.819-0.997; sensitivity = 95.65; specificity = 100; positive predictive value (PPV) = 100; negative predictive value (NPV) = 90.9 and negative likelihood ratio (NLR) = 0.043]. Regarding MCA, similarly, a RI ≤ 0.62 was ideal for differentiating between normal and asphyxiated neonates (AUC = 0.990 and 95% CI: 0.873-1; sensitivity = 91.30; specificity = 100; PPV = 91.2; NPV = 100 and NLR = 0.087).

CONCLUSION

For evaluating neonates clinically suspected of asphyxia, especially in centers with limited facilities such as MRI, DS can be used as a first line diagnostic modality and RI of ≤ 0.62 is an appropriate cut-off for the diagnosis of perinatal asphyxia.

Gray-scale ultrasound findings of hypoxic-ischemic injury in term infants

Brain ultrasound has become a critical tool for bedside screening and monitoring of hypoxic-ischemic injury in infants. Transfontanellar ultrasound in infants allows delineation of anatomical structures of the brain and posterior fossa. The technique's low cost, lack of ionizing radiation and repeatability make it a popular alternative to magnetic resonance imaging. The published literature on interpreting hypoxic-ischemic injury on brain ultrasound is wide and varied, yet diagnostic challenges remain when detecting subtle or diffuse changes. This pictorial essay summarizes and illustrates the spectrum of sonographic findings of hypoxic-ischemic injuries in term infants.

What assessments are currently used to investigate and diagnose cerebral visual impairment (CVI) in children? A systematic review

PURPOSE

Cerebral visual impairment (CVI) is the leading cause of childhood visual impairment in the developed world. Despite this, there are no agreed clinical guidelines for the investigation and diagnosis of the condition. Before development of such guidelines can commence, it is important to recognise which approaches are currently employed. This systematic review evaluated the literature to identify which methods of assessment are currently used to investigate and diagnose childhood CVI.

METHODS

Medline, Embase, CINAHL, Scopus and the Cochrane Library databases were systematically searched in January 2020 using defined search terms. Articles were included if they: (i) were research papers, conference abstracts or research protocols published in peer-reviewed scientific journals, or relevant textbooks; (ii) included a clinical investigation of CVI in children; (iii) provided an explanation or criteria to diagnose CVI and (iv) were specifically investigating cerebral/cortical visual impairment. Methods used to a) assess and b) diagnose CVI were extracted from included articles. 'Assessment scores' were assigned for each method employed by researchers to investigate and diagnose CVI to quantify and compare approaches between articles. A quality grading was also applied to each article.

RESULTS

Of 6454 identified articles, 45 met the inclusion criteria. From these, 10 categories of assessment utilised within included articles were identified: (1) Medical history, (2) Vision assessment/ophthalmologic examination, (3) Neuroimaging, (4) Visual behaviour and direct observation, (5) Structured history-taking, (6) Visual perception tests, (7) Ocular movement and posture assessment, (8) Intelligence/IQ assessment, (9) Clinical electrophysiology and (10) Neurodevelopmental tests. In terms of diagnostic criteria, the most commonly reported approach was one of exclusion, i.e., CVI was diagnosed when visual dysfunction could not be attributed to abnormalities detected in the anterior visual pathway.

CONCLUSION

There is a lack of common practice in the approaches used by clinicians to investigate and diagnose CVI in children. At present, a 'diagnosis of exclusion' remains the most common means to diagnose CVI. Development of clinical guidelines for assessment and diagnosis are necessary to ensure consistency in the diagnosis of CVI and the timely implementation of support to alleviate the impact of CVI on the child's daily living.

Management of Multi Organ Dysfunction in Neonatal Encephalopathy

Neonatal Encephalopathy (NE) describes neonates with disturbed neurological function in the first post-natal days of life. NE is an overall term that does not specify the etiology of the encephalopathy although it often involves hypoxia-ischaemia. In NE, although neurological dysfunction is part of the injury and is most predictive of long-term outcome, these infants may also have multiorgan injury and compromise, which further contribute to neurological impairment and long-term morbidities. Therapeutic hypothermia (TH) is the standard of care for moderate to severe NE. Infants with NE may have co-existing immune, respiratory, endocrine, renal, hepatic, and cardiac dysfunction that require individualized management and can be impacted by TH. Non-neurological organ dysfunction not only has a negative effect on long term outcome but may also influence the efficacy of treatments in the acute phase. Post resuscitative care involves stabilization and decisions regarding TH and management of multi-organ dysfunction. This management includes detailed neurological assessment, cardio-respiratory stabilization, glycaemic and fluid control, sepsis evaluation and antibiotics, seizure identification, and monitoring and responding to biochemical and coagulation derangements. The emergence of new biomarkers of specific organ injury may have predictive value and improve the definition of organ injury and prognosis. Further evidence-based research is needed to optimize management of NE, prevent further organ dysfunction and reduce neurodevelopmental impairment.

Neonatal Head Ultrasound: A Review and Update-Part 2: The Term Neonate and Analysis of Brain Anomalies

Neonatal head ultrasound has a key role in triaging neonates with antenatal imaging or postnatal clinical concerns. This article will discuss key features of various intracranial pathologies of concern in term infants. It will also illustrate various congenital malformations.

State-of-the-art neonatal cerebral ultrasound: technique and reporting

In the past three decades, cerebral ultrasound (CUS) has become a trusted technique to study the neonatal brain. It is a relatively cheap, non-invasive, bedside neuroimaging method available in nearly every hospital. Traditionally, CUS was used to detect major abnormalities, such as intraventricular hemorrhage (IVH), periventricular hemorrhagic infarction, post-hemorrhagic ventricular dilatation, and (cystic) periventricular leukomalacia (cPVL). The use of different acoustic windows, such as the mastoid and posterior fontanel, and ongoing technological developments, allows for recognizing other lesion patterns (e.g., cerebellar hemorrhage, perforator stroke, developmental venous anomaly). The CUS technique is still being improved with the use of higher transducer frequencies (7.5-18 MHz), 3D applications, advances in vascular imaging (e.g. ultrafast plane wave imaging), and improved B-mode image processing. Nevertheless, the helpfulness of CUS still highly depends on observer skills, knowledge, and experience. In this special article, we discuss how to perform a dedicated state-of-the-art neonatal CUS, and we provide suggestions for structured reporting and quality assessment.

Imaging the term neonatal brain

Brain imaging is important for the diagnosis and management of sick term neonates. Although ultrasound and computed tomography may provide some information, magnetic resonance imaging is now the brain imaging modality of choice because it is the most sensitive technique for detecting and quantifying brain abnormalities and does not expose infants to radiation. This statement describes the principles, roles and limitations of these three imaging modalities and makes recommendations for appropriate use in term neonates. The primary focus is the brain of term infants with neonatal encephalopathy, many of whom are diagnosed with hypoxic-ischemic encephalopathy.

The Utility of Cranial Ultrasound for Detection of Intracranial Hemorrhage in Infants

OBJECTIVE

The objective of this study was to evaluate the sensitivity and specificity of cranial ultrasound (CUS) for detection of intracranial hemorrhage (ICH) in infants with open fontanels.

METHODS

This was a retrospective study of infants younger than 2 years who had a CUS performed for the evaluation of potential ICH. We excluded patient with CUSs that were done for reasons related to prematurity, transplant or oncologic evaluations, routine follow-up or preoperative screen, or congenital and known perinatal anomalies. Two clinicians independently classified each of the patients with ICH into significant or insignificant based on the radiology reports.

RESULTS

Of 4948 CUS studies performed during the 5-year study period, 283 studies fit the inclusion criteria. Patient age ranged from 0 to 458 days, with a median of 33 days. There were 39 total cases of ICH detected, with 27 significant bleeds and 12 insignificant bleeds. Using computed tomography, magnetic resonance imaging, or clinical outcome as criterion standard, the overall ultrasound sensitivity and specificity for bleed were 67% (confidence interval [CI], 50%-81%) and 99% (CI, 97%-100%), respectively. For those with significant bleeds, the overall sensitivity was 81% (CI, 62%-94%), and for those with insignificant bleeds, it was 33% (CI, 1%-65%).

CONCLUSIONS

The sensitivity of CUS is inadequate to justify its use as a screening tool for detection of ICH in young infants.

Universal Head Ultrasound Screening in Full-term Neonates: A Retrospective Analysis of 6771 Infants

BACKGROUND

Full-term neonates may have asymptomatic cranial injuries at birth and head ultrasound screening could be useful for early diagnosis. The aim of this study was to assess the prevalence and type of intracranial abnormalities and the usefulness of head ultrasound screening in these infants.

METHODS

Head ultrasound screening was performed on all full-term neonates (gestational age between 37 and 42 weeks), born at Sant'Anna University Hospital of Ferrara, Italy, from June 1, 2008 through May 31, 2013. Ultrasound findings were categorized into three groups: normal, minor, and major anomalies.

RESULTS

All full-term neonates (6771) born at our hospital underwent head ultrasound screening. One hundred fourteen of 6771 (1.7%) presented ultrasound abnormalities, whereas 6657 were normal or exhibited insignificant findings. In 101 of 114 (88.6%), abnormalities were minor, and only 13 infants had major abnormalities (0.19% of all full-term newborns). All neonates with major abnormalities presented with either microcephaly or abnormal neurological evaluations. Only one individual with major abnormalities was detected exclusively by ultrasound.

CONCLUSIONS

The number of significant anomalies detected by head ultrasound screening in asymptomatic full-term neonates born during the study period was low. Therefore, there is no indication for routine general head ultrasound screening in these patients. However, even if low, in neonates who have neurological abnormalities, risk factors or suspected brain malformations, head ultrasound screening may play an important role in the early diagnosis of intracranial anomalies.

Neonatal Hypoxia Ischaemia: Mechanisms, Models, and Therapeutic Challenges

Neonatal hypoxia-ischaemia (HI) is the most common cause of death and disability in human neonates, and is often associated with persistent motor, sensory, and cognitive impairment. Improved intensive care technology has increased survival without preventing neurological disorder, increasing morbidity throughout the adult population. Early preventative or neuroprotective interventions have the potential to rescue brain development in neonates, yet only one therapeutic intervention is currently licensed for use in developed countries. Recent investigations of the transient cortical layer known as subplate, especially regarding subplate's secretory role, opens up a novel set of potential molecular modulators of neonatal HI injury. This review examines the biological mechanisms of human neonatal HI, discusses evidence for the relevance of subplate-secreted molecules to this condition, and evaluates available animal models. Neuroserpin, a neuronally released neuroprotective factor, is discussed as a case study for developing new potential pharmacological interventions for use post-ischaemic injury.

‘State-of-the-Art’ Neonatal Cranial Ultrasound

Cranial ultrasound (cUS) provides bedside imaging access to the neonatal brain. Modern scanners and the use of various acoustic windows give detail not only of the well known pathologies met in the preterm infant, but also allow assessment of more subtle aspects of normal and abnormal brain growth and development. cUS is also very helpful in the early diagnosis of the many aetiologies of neonatal encephalopathy and seizures in the term infant and the subsequent monitoring of progress of hypoxic-ischaemic brain injury. Training issues in cUS need to be addressed.

A study of neurosonogram abnormalities, clinical correlation with neurosonogram findings, and immediate outcome of high-risk neonates in Neonatal Intensive Care Unit

BACKGROUND

Neonatal sonography of the brain is now an essential part of newborn care, particularly in high risk and unstable premature infants. Cranial ultrasound is the most available and easily repeatable imaging technique for the neonatal brain showing brain development and the most frequently occurring forms of cerebral injury in the preterm and terms. This study aims to assess the importance of cranial ultrasound as an investigatory modality for high-risk neonates and to find out the morphology of various cerebral lesions and correlate clinically.

METHODOLOGY

An observational correlation clinical study was conducted at Sardar Patel Medical College, Bikaner involving 100 high-risk neonates admitted to Neonatal Intensive Care Unit (NICU) who was subjected to neurosonography on selected days as per protocol. Perinatal details were recorded, and clinical examination with appropriate investigations was done. The cranial ultrasound was done, and morphology of various findings was studied and recorded. Clinical correlation with cranial ultrasound findings and follow-up was done.

RESULTS

On cranial ultrasound, 38% of neonates had abnormal findings. Twelve percent of these had evidence of intracranial bleed, 13% periventricular echogenicity, 7% had ventriculomegaly, 2% had cerebral edema, and 1% had leukomalacia. Three neonates had findings suggestive of simple cyst in middle cranial fossa, agenesis of corpus callosum, and choroid plexus cyst.

CONCLUSIONS

Cranial ultrasonography is the best point of care neuroimaging method available for high-risk neonates. It is critical as an investigatory modality in NICU and effectively documents morphology of cerebral damage.

Monitoring of newborns at high risk for brain injury

Due to the increasing number of surviving preterm newborns and to the recognition of therapeutic hypothermia as the current gold standard in newborns with hypoxic-ischaemic encephalopathy, there has been a growing interest in the implementation of brain monitoring tools in newborns at high risk for neurological disorders.Among the most frequent neurological conditions and presentations in the neonatal period, neonatal seizures and neonatal status epilepticus, paroxysmal non-epileptic motor phenomena, hypoxic-ischaemic encephalopathy, white matter injury of prematurity and stroke require specific approaches to diagnosis. In this review we will describe the characteristics, aims, indications and limitations of routinely available diagnostic techniques such as conventional and amplitude-integrated EEG, evoked potentials, cranial ultrasound and brain MRI. We will conclude by briefly outlining potential future perspectives from research studies.

Neurosonography: in pursuit of an optimized examination

This article emphasizes technical factors that are helpful for optimizing sonographic examinations of the brain in preterm and term neonates. It also reviews existing data regarding the accuracy of neurosonographic examinations relative to MR. Many neurosonographic signs are subtle and can be easily overlooked, which could lead to delayed diagnosis or misdiagnosis. Therefore meticulous attention to sonographic technique is required to maximize the diagnostic utility of this modality. Although MR images of the brain often depict abnormalities more clearly than sonography, neurosonography continues to be an exceptionally valuable tool for evaluation of the neonatal brain, even in full-term neonates. Furthermore, its accuracy is greater, even in the latter age group, than many older publications suggest. Prospective studies using state-of-the-art equipment comparing findings on sonography and MR are needed to better understand how the accuracy of these modalities changes with refinements in equipment and to help us better understand the role of neurosonography relative to MR.

Posterior fossa abnormalities in high-risk term infants: comparison of ultrasound and MRI

Objectives

We aimed to assess the characteristics of posterior fossa (PF) abnormalities in a cohort of high-risk term neonates, as well as the diagnostic performance of cranial ultrasound (CUS) with additional mastoid fontanelle (MF) views for the detection of these abnormalities, with magnetic resonance imaging (MRI) being the reference standard.

Methods

In this retrospective study, 113 term neonates with CUS and subsequent MRI were included. Sensitivity, specificity, and predictive values of routine CUS and CUS with MF views were calculated.

Results

Posterior fossa abnormalities were diagnosed on CUS in 46 of 113 infants. MRI confirmed these findings in 43 and showed additional abnormalities in 32 infants. The sensitivity and specificity of anterior fontanelle views for major PF abnormalities as seen on MRI were 16 % and 99 %. Adding MF views increased the sensitivity of US to 82 %. The sensitivity and specificity of MF views for the detection of any (major or minor) PF abnormality were 57 % and 95 %. Especially acute hypoxic-ischemic injury and small subdural and punctate cerebellar haemorrhage remained undetected by CUS.

Conclusions

PF abnormalities are frequent in high-risk term infants. MF-CUS enables early diagnosis of major PF abnormalities. We therefore advocate to perform MF-CUS in high-risk term neonates.

Key Points

• Posterior fossa abnormalities are a frequent finding in high-risk term infants.

• Adding mastoid fontanelle views improves ultrasound detection of clinically relevant abnormalities.

• Hypoxic-ischemic injury and small posterior fossa haemorrhages are better detected with MRI.

• Cranial ultrasound examination should include mastoid fontanelle views in high-risk term neonates.

Neonatal neurosonography

Neonatal neurosonography is used commonly to evaluate the central nervous system in the neonatal intensive care setting. The procedure can be performed at the bedside in these critically ill patients who may suffer from hemodynamic and thermoregulatory instability and often require mechanical ventilation. This article reviews current recommendations regarding neurosonography technique, pathophysiology, and imaging of intracranial insults including hemorrhage, white matter injury, infarction, and hypoxic-ischemic encephalopathy.

Cranial sonography in extremely preterm infants

Survival rates of extremely preterm infants have risen dramatically, paralleling improvements in prenatal and neonatal care. Cranial sonography is the primary imaging technique for the evaluation of brain injury in these patients. Extremely preterm infants have some unique features related to ongoing maturation, and associated findings on cranial sonography should be considered for accurate and early diagnosis. The aim of this pictorial essay is to illustrate normal anatomy, normal variants, and pitfalls that lead to misinterpretation of cranial sonography in extremely preterm infants.

White-gray matter echogenicity ratio and resistive index: sonographic bedside markers of cerebral hypoxic-ischemic injury/edema?

OBJECTIVE

Head ultrasonography (HUS) is a reliable and easy to perform bedside imaging technique that can give valuable information about degree of brain injury/edema after perinatal asphyxia in term neonates. The goals of our study were to determine whether semiquantitative markers such as standardized white matter/gray matter (WM/GM) echogenicity ratio and resistive index (RI) value measured by HUS differs between asphyxiated term neonates and healthy controls.

STUDY DESIGN

Thirty-one carefully selected term neonates who suffered from perinatal hypoxic-ischemic encephalopathy (HIE) were included in the study. The ratio of the WM/GM echogenicity of the cingulate gyrus was calculated. In addition, the RI value was measured in the anterior cerebral artery. US scalars were compared with 11 healthy neonates.

RESULT

WM/GM ratio is significantly increased and RI value significantly decreased in asphyxiated term neonates compared with healthy subjects.

CONCLUSION

WM/GM ratio and RI value allows discriminating between asphyxiated neonates and healthy subjects. These US scalars may serve as valuable, easy to acquire semiquantitative bedside markers of brain HIE, when magnetic resonance imaging is unavailable or cannot be performed in the acute setting.

Neonatal ischemic brain injury: what every radiologist needs to know

We present a pictorial review of neonatal ischemic brain injury and look at its pathophysiology, imaging features and differential diagnoses from a radiologist's perspective. The concept of perinatal stroke is defined and its distinction from hypoxic-ischemic injury is emphasized. A brief review of recent imaging advances is included and a diagnostic approach to neonatal ischemic brain injury is suggested.

Abnormal corpus callosum in neonates after hypoxic-ischemic injury

BACKGROUND

Literature regarding callosal injury after hypoxic-ischemic injury (HII) is scant.

OBJECTIVE

To present the MRI and US findings of callosal injury after HII.

MATERIALS AND METHODS

MRI and US studies of 76 neonates were evaluated for HII and 53 were considered positive.

RESULTS

Of the 53 neonates with HII, 40 demonstrated restricted diffusion on DWI; of these, 30 revealed callosal involvement. Nine of the 13 neonates with normal DWI, whose routine MRI images were compatible with HII, were imaged after 1 week of age. Five out of ten neonates imaged during the 1st week of life who did not show callosal restriction on DWI had predominantly basal ganglia injury. Callosal US images were regarded as abnormal in 16 out of the 53 neonates with HII, 15 of which revealed concomitant restricted diffusion on DWI.

CONCLUSION

Callosal injuries are common after HII. DWI is effective in confirming these injuries and easily demonstrates injury if performed prior to 1 week of age. The restricted diffusion demonstrated after this time could be attributed to continued injury. US is not a sensitive modality for callosal injury detection; however, abnormally increased callosal echogenicity might be a specific marker of injury in this setting.

Birth-related injury to the head and cervical spine in neonates

Birth-related injury is defined as any traumatic or ischemic event sustained during the process of delivery. Perinatally acquired disease processes secondary to birth-related injury can be traumatic or ischemic in nature. In this article, the authors focus on traumatic/mechanical injuries. Other diseases of the perinatal time period, including germinal matrix hemorrhages and hypoxic-ischemic encephalopathy, are beyond the objective of this review.

Head Ultrasound and MR imaging in the evaluation of neonatal encephalopathy: competitive or complementary imaging studies?

Magnetic resonance (MR) imaging is superior to ultrasonography (US) for the evaluation and prognostication of neonates with neonatal encephalopathy (NE). Nonetheless, US may provide important information early in the course of NE and can be used to document the evolution of lesions. This article provides an overview of useful findings in the US evaluation of infants with NE. Although many of the findings do not appear as conspicuous or as extensively as they do on MR imaging, recognition and familiarity with subtle head US abnormalities may allow head US to play an important complementary role to MR imaging in the evaluation of infants with NE.

Myth: cerebral palsy cannot be predicted by neonatal brain imaging

There is controversy in the literature about the value of brain imaging in neonates regarding the prediction of cerebral palsy (CP). The aim of this review was to unravel the myth that CP cannot be predicted by neuroimaging in neonates. Major intracranial lesions in the preterm infant should be recognized with sequential cranial ultrasound and will predict those with non-ambulatory CP. Magnetic resonance imaging (MRI) at term-equivalent age will refine the prediction by assessment of myelination of the posterior limb of the internal capsule. Prediction of motor outcome in preterm infants with subtle white matter injury remains difficult, even with conventional MRI. MRI is a better tool to predict outcome in the term infant with hypoxic-ischaemic encephalopathy or neonatal stroke. The use of diffusion-weighted imaging as an additional sequence adds to the predictive value for motor outcome. Sequential and dedicated neuroimaging should enable us to predict motor outcome in high risk newborns infants.

State-of-the-art cranial sonography: Part 1, modern techniques and image interpretation

OBJECTIVE

In this era of radiation awareness, high-quality ultrasound is more important than ever. Although cranial sonography equipment has advanced greatly, application of modern techniques has not been utilized in a fashion commensurate to other cross-sectional modalities. This article will describe modern cranial sonography techniques, including the utility of linear imaging, use of additional fontanels, and screening Doppler imaging.

CONCLUSION

When modern protocols are used, cranial sonography is highly accurate for the detection of cranial abnormalities.

Non-invasive imaging of intracranial pediatric vascular lesions

OBJECTIVES

The goal of this review is to discuss the different non-invasive imaging techniques as well as the age-specific pediatric vascular pathologies and their imaging features.

MATERIAL AND METHODS

Ultrasound, computed tomography, and magnetic resonance imaging features of pediatric ischemic stroke, intracranial hemorrhage, aneurysms, cavernomas, developmental venous anomalies, and arteriovenous malformations are presented. In addition, multiple non-invasive angiographic techniques (CT and MR angiography) and functional MRI sequences (diffusion, perfusion, and susceptibility-weighted imaging) are discussed.

CONCLUSION

Neurovascular imaging plays a central role in the early, sensitive, and specific diagnosis of pediatric intracranial vascular disorders. A detailed knowledge of the quality and exact angioarchitecture of pediatric vascular pathologies as well as their impact on the cerebral hemo-dynamics is essential to guide and monitor treatment options and to predict functional outcome.

Neonatal encephalopathy: a prospective comparison of head US and MRI

BACKGROUND

Head US, the cornerstone neuroimaging modality in neonates, is believed to be less sensitive than MRI for detecting hypoxic ischemic injury (HII). Most reports comparing these modalities are retrospective and have a long interval between the exams.

OBJECTIVE

To prospectively characterize the range of abnormalities found in US examinations performed within 2 h of brain MRI in encephalopathic neonates.

MATERIALS AND METHODS

A total of 76 consecutive exams met our inclusion criteria. Diagnostic performance of the US images was prospectively compared with MRI.

RESULTS

MRI was considered positive for HII in 53 neonates. Of the remaining 23, MRI was negative for HII in 9, showed white matter abnormalities unrelated to HII in 8, and was inconclusive in 6. Of the 70 neonates with conclusive examinations, the US exam was regarded as positive in 67. Diagnostic accuracy of US was 95.7%.

CONCLUSION

Our study demonstrates that US should still be regarded as a screening test in neonates. US is more sensitive for the detection of injury than previously reported, and more attention should be paid to proper US technique. MRI shows disease more extensively and should be accomplished as early as possible.

Patterns of neonatal hypoxic-ischaemic brain injury

Enormous progress has been made in assessing the neonatal brain, using magnetic resonance imaging (MRI). In this review, we will describe the use of MRI and proton magnetic resonance spectroscopy in detecting different patterns of brain injury in (full-term) human neonates following hypoxic–ischaemic brain injury and indicate the relevance of these findings in predicting neurodevelopmental outcome.

MR imaging of term infants with hypoxic-ischaemic encephalopathy as a predictor of neurodevelopmental outcome and late MRI appearances

BACKGROUND

Morbidity attributable to hypoxic-ischaemic injury (HIE) in the perinatal period remains problematic, and timely and accurate assessment of the degree of injury is required for clinical management and prognosis. Conventional MR sequences typically appear normal in the first 48 h post HIE. While diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) maps register the injury earlier, perhaps within the first 24 h, it has been suggested that there may be a propensity at that early stage to underestimate the lesion severity or extent.

OBJECTIVE

To assess whether MR imaging that included DWI, measured ADC values and T1- and T2-weighted sequences ultimately correlated with either neurodevelopmental outcome or with late MR imaging at 2 years of age. In addition, we wished to compare the performance of MR imaging with cranial US imaging.

MATERIALS AND METHODS

All infants presenting with HIE who had an MRI within 10 days of life were eligible for enrollment and subsequently underwent a full neurodevelopmental assessment at 2 years of age. All children underwent repeat MRI at this time. All neonates had at least one cranial US study. The US findings were categorized as normal, abnormalities confined to the cerebral cortex and subcortical white matter, isolated central grey matter hyperechogenicity, and central hyperechogenicity combined with cerebral cortical/subcortical changes. All MRI studies were retrospectively reviewed by three radiologists. The patterns of injury on the early DWI and ADC maps and early T1- and T2-W studies were recorded as diffuse, central, watershed or atypical. The patterns of signal abnormality were assessed using a scoring system that yielded four separate scores [basal ganglia (BG), watershed (W), BG/W and summation (S)] for the three sets of images, a total of 12 scores in all. The appearance of the posterior limb of the internal capsule (PLIC) on T1-W inversion recovery sequences and of the corpus callosum on all sequences was also documented. After detailed neurodevelopmental assessment at 2 years of age, infants were classified into two groups according to whether they had a favourable or unfavourable outcome.

RESULTS

Of the 26 infants, 6 infants died before formal assessment at the age of 2 years. A further 5 infants had moderate to severe cerebral palsy in addition to severe cognitive impairment. The remaining 15 infants were categorized in the favourable outcome group. The US appearance performed well in terms of predicting final outcome (P = 0.005). The pattern of ischaemia seen on early MRI was a significant predictor of outcome (P < 0.0001). The BG, BG/W and S scores of the diffusion imaging were significantly associated with outcome (P < 0.0001, P < 0.0001 and P = 0.0005 respectively). DWI was predictive of outcome group (P < 0.0001), as were the early T1- and T2-W sequences (P = 0.002) and cranial US (P = 0.005). Assessment of the PLIC in infants with watershed or atypical patterns of ischaemia was found to be less reliable in predicting outcome. The measured ADC value in the PLIC was significantly reduced in those children who had an unfavourable outcome (P = 0.03).

CONCLUSION

While early MRI performed better than cranial US, the sonography findings were useful. The pattern of ischaemia on early MRI was a good predictor of prognosis. All infants with watershed or atypical patterns had a favourable outcome. The majority of infants with central patterns of ischaemia had an unfavourable outcome and all infants with a diffuse pattern had an unfavourable outcome. DWI was predictive of outcome group, as were early T1- and T2-W sequences and cranial US.

Infant craniospinal ultrasonography: beyond hemorrhage and hydrocephalus

Ultrasonography is widely used for screening for neonatal intracranial hemorrhage, hydrocephalus, and cord tethering in young infants. Proper interpretation of infant cranial and spinal ultrasound examinations requires not only familiarity with the appearances of these disorders, but also recognition of imaging artifacts capable of mimicking pathology and awareness of developmental variants and conditions that occupy a borderline position along the spectrum from normal to abnormal. This article will review the current understanding of the ultrasonographic characteristics and clinical relevance of these imaging artifacts, developmental variants, and quasi-pathologic conditions to avoid diagnostic pitfalls and guide appropriate patient management.

Patterns of neonatal hypoxic-ischaemic brain injury

Enormous progress has been made in assessing the neonatal brain, using magnetic resonance imaging (MRI). In this review, we will describe the use of MRI and proton magnetic resonance spectroscopy in detecting different patterns of brain injury in (full-term) human neonates following hypoxic-ischaemic brain injury and indicate the relevance of these findings in predicting neurodevelopmental outcome.

Evolving understanding of hypoxic-ischemic encephalopathy in the term infant

Our aim was to document changes in the evaluation and prognosis of term-born infants with neonatal encephalopathy of hypoxic-ischemic origin, with particular reference to our own experiences and influences, and to summarize the debate on causation and the relative importance of antenatal and perinatal factors. High quality neonatal cranial ultrasound and magnetic resonance imaging and spectroscopy have enabled the accurate early visualization of different patterns of hypoxic-ischemic brain injury and prediction of their associated outcomes. Long-term follow-up shows that cognitive and memory difficulties may follow even in children without motor deficits. The very early use of electrophysiologic methods has allowed broad prognostic categorization of infants when this is not possible from clinical assessment or imaging, providing a rationale for entry into intervention trials, such as therapeutic hypothermia. This work has also shown that most of these infants have evidence of acute hypoxic-ischemic brain injury that explains their symptoms and outcomes.

Hypoxic-ischaemic Brain Injury in Young Infants

Many imaging techniques are available for the detection of hypoxic-ischaemic brain injury in young infants.This paper presents an overview of the imaging findings in hypoxic-ischaemic brain injury with an emphasis on MR imaging. Key words: Hypoxia-ischaemia, Infants, Imaging, MR imaging, Neonates, Ultrasonography

Quality of general movements in term infants with asphyxia

BACKGROUND

Perinatal asphyxia may result in a developmental disorder. A recently developed non-invasive tool to investigate brain function at an early age is the assessment of general movements (GMs).

AIM

To evaluate relationships between perinatal risk factors and the quality of GMs in the neonatal period and at 3 months in term newborns with asphyxia in a secondary paediatric setting.

METHODS

64 term (>36 weeks postmenstrual age (PMA)) infants with perinatal asphyxia were studied. GMs were assessed at 'writhing' GM age (38-47 weeks PMA) and at 'fidgety' GM age (48-56 weeks PMA). Pre- and perinatal factors were collected in a standardized way.

RESULTS

Multivariate analysis revealed that DA GMs at 'writhing' age mainly correlated with asphyxia related illness. DA GMs at 'fidgety' age correlated in particular with abnormalities on the neonatal ultrasound scan of the brain.

CONCLUSION

In secondary paediatric settings GM-assessment especially around 3 months is a valuable tool for the assessment of the integrity of the nervous system in term infants with asphyxia.