Advanced MR brain imaging. Why?

Radiological findings of abnormalities associated with congenital Zika virus infection: conclusions from World Radiology Day 2016

In July 2015, Brazil reported an association between Zika virus infection and Guillain-Barre syndrome, and then in October 2015, between Zika and microcephaly. Most countries and territories in the Region of the Americas were later affected by the virus, creating a public health emergency.

Each year, the Pan American Health Organization (PAHO), Regional Office of the World Health Organization commemorates World Radiology Day (WRD), which highlights the role of radiology in public health. In 2016, PAHO devoted its WRD efforts to the Zika infection. Experts and partners presented and discussed the various radiological findings of Zika infection, the crucial role of obstetric ultrasound in the screening and monitoring of abnormalities associated with confirmed Zika virus infection, and the appropriateness of utilizing other neuroimaging technologies to study brain abnormalities in neonates and infants with prenatal Zika virus infection. The conclusions of WRD 2016 recommend that upon confirmation, prenatal ultrasound be used as the main tool to investigate and monitor suspected cases, with subsequent multidisciplinary postnatal assessments that include neuropediatric clinical studies and relevant neuroimaging. Additionally, radiology technicians should be adequately trained and a quality assurance program should be implemented to ensure timely, safe, and accurate diagnosis.

Neonatal neuroimaging findings in inborn errors of metabolism

Individually, metabolic disorders are rare, but overall they account for a significant number of neonatal disorders affecting the central nervous system. The neonatal clinical manifestations of inborn errors of metabolism (IEMs) are characterized by nonspecific systemic symptoms that may mimic more common acute neonatal disorders like sepsis, severe heart insufficiency, or neonatal hypoxic-ischemic encephalopathy. Certain IEMs presenting in the neonatal period may also be complicated by sepsis and cardiomyopathy. Early diagnosis is mandatory to prevent death and permanent long-term neurological impairments. Although neuroimaging findings are rarely specific, they play a key role in suggesting the correct diagnosis, limiting the differential diagnosis, and may consequently allow early initiation of targeted metabolic and genetic laboratory investigations and treatment. Neuroimaging may be especially helpful to distinguish metabolic disorders from other more common causes of neonatal encephalopathy, as a newborn may present with an IEM prior to the availability of the newborn screening results. It is therefore important that neonatologists, pediatric neurologists, and pediatric neuroradiologists are familiar with the neuroimaging findings of metabolic disorders presenting in the neonatal time period.

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.

Neuroimaging of pediatric posterior fossa tumors including review of the literature

Conventional, anatomical MRI is an essential tool for diagnosis and evaluation of location, quality, and extent of posterior fossa tumors, but offers limited information regarding tumor grade and type. Advanced MRI techniques such as diffusion weighted imaging (DWI) and diffusion tensor imaging (DTI) may improve the specific diagnosis of brain tumors in the posterior fossa in children. In this review the conventional neuroimaging findings, as well as the DWI, and DTI characteristics of common pediatric posterior fossa tumors are discussed and summarized.

Diffusion tensor imaging of the maturing paediatric cervical spinal cord: from the neonate to the young adult

OBJECTIVE

Normative apparent diffusion coefficient (ADC) and fractional anisotropy (FA) metrics of the brain have been published previously. However, no larger studies evaluated the normal evolution of ADC/FA metrics of the maturing paediatric spinal cord. Goal of this study is to evaluate the age-dependent evolution of the ADC/FA values of the developing/maturing normal cervical spinal cord (CSC).

PATIENTS AND METHODS

Forty-one subjects, aged less than 18 years with a negative spinal MRI study and no systemic central nervous disease, underwent diffusion tensor imaging (DTI) of the CSC. DTI metrics were measured in the centre of the CSC. Regression and ANCOVA analyses were performed to evaluate the association between ADC/FA values and age and its potential modification by sex.

RESULTS

A linear model emerged as the best fit for our data. ADC showed a continuous decrease with age; FA showed a continuous increase with age.

CONCLUSION

The simultaneous age-related ADC decrease and FA increase likely reflect progressive maturation, myelination and fibre packing within the CSC similar to that observed in the brain. Collection of age-dependent normative DTI metrics may be helpful in the early identification and quantification of altered water diffusion in a variety of pathologies affecting the developing paediatric spinal cord.

Diffusion-weighted and diffusion tensor imaging of the brain, made easy

Diffusion-weighted and diffusion tensor imaging (DWI/DTI) has revolutionized clinical neuroimaging. Pathology may be detected earlier and with greater specificity than with conventional magnetic resonance imaging sequences. In addition, DWI/DTI allows exploring the microarchitecture of the brain. A detailed knowledge of the basics of DWI/DTI is mandatory to better understand pathology encountered and to avoid misinterpretation of typical DWI/DTI artifacts. This article reviews the basic physics of DWI/DTI exemplified by several classical clinical cases.